Disturbances to Air-Layer Skin-Friction Drag Reduction at High Reynolds Numbers

NASA Astrophysics Data System (ADS)

Dowling, David; Elbing, Brian; Makiharju, Simo; Wiggins, Andrew; Perlin, Marc; Ceccio, Steven

2009-11-01

Skin friction drag on a flat surface may be reduced by more than 80% when a layer of air separates the surface from a flowing liquid compared to when such an air layer is absent. Past large-scale experiments utilizing the US Navy's Large Cavitation Channel and a flat-plate test model 3 m wide and 12.9 m long have demonstrated air layer drag reduction (ALDR) on both smooth and rough surfaces at water flow speeds sufficient to reach downstream-distance-based Reynolds numbers exceeding 100 million. For these experiments, the incoming flow conditions, surface orientation, air injection geometry, and buoyancy forces all favored air layer formation. The results presented here extend this prior work to include the effects that vortex generators and free stream flow unsteadiness have on ALDR to assess its robustness for application to ocean-going ships. Measurements include skin friction, static pressure, airflow rate, video of the flow field downstream of the injector, and profiles of the flowing air-water mixture when the injected air forms bubbles, when it is in transition to an air layer, and when the air layer is fully formed. From these, and the prior measurements, ALDR's viability for full-scale applications is assessed.

The drag force on a subsonic projectile in a fluid complex plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ivlev, A. V.; Zhukhovitskii, D. I.

2012-09-15

The incompressible Navier-Stokes equation is employed to describe a subsonic particle flow induced in complex plasmas by a moving projectile. Drag forces acting on the projectile in different flow regimes are calculated. It is shown that, along with the regular neutral gas drag, there is an additional force exerted on the projectile due to dissipation in the surrounding particle fluid. This additional force provides significant contribution to the total drag.

Dragging a floating horizontal cylinder

NASA Astrophysics Data System (ADS)

Lee, Duck-Gyu; Kim, Ho-Young

2010-11-01

A cylinder immersed in a fluid stream experiences a drag, and it is well known that the drag coefficient is a function of the Reynolds number only. Here we study the force exerted on a long horizontal cylinder that is dragged perpendicular to its axis while floating on an air-water interface with a high Reynolds number. In addition to the flow-induced drag, the floating body is subjected to capillary forces along the contact line where the three phases of liquid/solid/gas meet. We first theoretically predict the meniscus profile around the horizontally moving cylinder assuming the potential flow, and show that the profile is in good agreement with that obtained experimentally. Then we compare our theoretical predictions and experimental measurement results for the drag coefficient of a floating horizontal cylinder that is given by a function of the Weber number and the Bond number. This study can help us to understand the horizontal motion of partially submerged objects at air-liquid interface, such as semi-aquatic insects and marine plants.

STS-92 - Landing at Edwards Air Force Base

NASA Image and Video Library

2000-10-24

With its drag parachute deployed to help slow it down, the Space Shuttle Discovery rolls down the runway after landing at Edwards Air Force Base in Southern California at the conclusion of mission STS-92 on October 24, 2000.

Miniature drag-force anemometer

NASA Technical Reports Server (NTRS)

Krause, L. N.; Fralick, G. C.

1977-01-01

A miniature drag-force anemometer is described which is capable of measuring dynamic velocity head and flow direction. The anemometer consists of a silicon cantilever beam 2.5 mm long, 1.5 mm wide, and 0.25 mm thick with an integrated diffused strain-gage bridge, located at the base of the beam, as the force measuring element. The dynamics of the beam are like those of a second-order system with a natural frequency of about 42 kHz and a damping coefficient of 0.007. The anemometer can be used in both forward and reversed flow. Measured flow characteristics up to Mach 0.6 are presented along with application examples including turbulence measurements.

Direct Measurements of Drag Forces in C. elegans Crawling Locomotion

PubMed Central

Rabets, Yegor; Backholm, Matilda; Dalnoki-Veress, Kari; Ryu, William S.

2014-01-01

With a simple and versatile microcantilever-based force measurement technique, we have probed the drag forces involved in Caenorhabditis elegans locomotion. As a worm crawls on an agar surface, we found that substrate viscoelasticity introduces nonlinearities in the force-velocity relationships, yielding nonconstant drag coefficients that are not captured by original resistive force theory. A major contributing factor to these nonlinearities is the formation of a shallow groove on the agar surface. We measured both the adhesion forces that cause the worm’s body to settle into the agar and the resulting dynamics of groove formation. Furthermore, we quantified the locomotive forces produced by C. elegans undulatory motions on a wet viscoelastic agar surface. We show that an extension of resistive force theory is able to use the dynamics of a nematode’s body shape along with the measured drag coefficients to predict the forces generated by a crawling nematode. PMID:25418179

Intercooler cooling-air weight flow and pressure drop for minimum drag loss

NASA Technical Reports Server (NTRS)

Reuter, J George; Valerino, Michael F

1944-01-01

An analysis has been made of the drag losses in airplane flight of cross-flow plate and tubular intercoolers to determine the cooling-air weight flow and pressure drop that give a minimum drag loss for any given cooling effectiveness and, thus, a maximum power-plant net gain due to charge-air cooling. The drag losses considered in this analysis are those due to (1) the extra drag imposed on the airplane by the weight of the intercooler, its duct, and its supports and (2) the drag sustained by the cooling air in flowing through the intercooler and its duct. The investigation covers a range of conditions of altitude, airspeed, lift-drag ratio, supercharger-pressure ratio, and supercharger adiabatic efficiency. The optimum values of cooling air pressure drop and weight flow ratio are tabulated. Curves are presented to illustrate the results of the analysis.

Space Age Swimsuit Reduces Drag, Breaks Records

NASA Technical Reports Server (NTRS)

2008-01-01

A space shuttle and a competitive swimmer have a lot more in common than people might realize: Among other forces, both have to contend with the slowing influence of drag. NASA s Aeronautics Research Mission Directorate focuses primarily on improving flight efficiency and generally on fluid dynamics, especially the forces of pressure and viscous drag, which are the same for bodies moving through air as for bodies moving through water. Viscous drag is the force of friction that slows down a moving object through a substance, like air or water. NASA uses wind tunnels for fluid dynamics research, studying the forces of friction in gasses and liquids. Pressure forces, according to Langley Research Center s Stephen Wilkinson, dictate the optimal shape and performance of an airplane or other aero/hydro-dynamic body. In both high-speed flight and swimming, says Wilkinson, a thin boundary layer of reduced velocity fluid surrounds the moving body; this layer is about 2 centimeters thick for a swimmer.

STS-66 landing at Edwards Air Force Base

NASA Technical Reports Server (NTRS)

1994-01-01

The drag chute is fully deployed as the Space Shuttle Atlantis heads toward a stop at Edwards Air Force Base in southern California, ending a successful 10 day, 22 hour and 34 minute space mission. Landing occured at 7:34 a.m. (PST), November 14, 1994.

STS-67 landing at Edwards Air Force Base

NASA Technical Reports Server (NTRS)

1995-01-01

The drag chute is fully deployed in this view of the Space Shuttle Endeavour as it completes a mission of almost 17 days duration in space on runway 22 at Edwards Air Force Base in southern California. Landing occurred at 1:46 p.m. (EST), March 18, 1995.

Collisional model of the drag force of granular impact

NASA Astrophysics Data System (ADS)

Stevens Bester, Cacey; Behringer, Robert P.

2017-06-01

A dense, dry granular target can cause a free-falling intruding object to come to an abrupt stop as its momentum is lost to the grains. An empirical force law describes this process, characterizing the stopping force as the sum of depth-dependent friction and velocity-dependent inertial drag. However, a complete interpretation of the stopping force, incorporating grain-scale interactions during impact, remains unresolved. Here, the momentum transfer is proposed to occur through sporadic, normal collisions with clusters of high force-carrying grains at the intruder's surface. To test this model in impact experiments, we determine the forces acting on an intruder decelerating through a dense granular medium using high-speed imaging of its trajectory. We vary the geometry of the impacting object to infer intruder-grain interactions. As a result, we connect the inertial drag to the effect of intruder shape based on the proposed collisional model. These impact studies serve as an approach to understand dynamic force transmission in granular media.

Airflow in Gravity Sewers - Determination of Wastewater Drag Coefficient.

PubMed

Bentzen, Thomas Ruby; Østertoft, Kristian Kilsgaard; Vollertsen, Jes; Fuglsang, Emil Dietz; Nielsen, Asbjørn Haaning

2016-03-01

Several experiments have been conducted in order to improve the understanding of the wastewater drag and the wall frictional force acting on the headspace air in gravity sewers. The aim of the study is to improve the data basis for a numerical model of natural sewer ventilation. The results of the study shows that by integrating the top/side wall shear stresses the log-law models for the air velocity distribution along the unwetted perimeter resulted in a good agreement with the friction forces calculated by use of the Colebrook-White formula for hydraulic smooth pipes. Secondly, the water surface drags were found by log-law models of the velocity distribution in turbulent flows to fit velocity profiles measured from the water surface and by integrating the water surface drags along the wetted perimeter, mean water surface drags were found and a measure of the water surface drag coefficient was found.

Four and eight faceted domes effects on drag force and image in missile application

NASA Astrophysics Data System (ADS)

Sakarya, Doǧan Uǧur

2017-10-01

Drag force effect is an important aspect of range performance in missile applications. Depending on domes geometry, this effect can be decreased. Hemispherical domes have great image uniformity but more drag force has an effect on it. Four and eight faceted domes decrease drag force. However, environment reflections cause a noise in a system. Also depending on the faceted domes shape, sun and other sources in the environment are deformed in the face of them and these deformed objects result in a false target in an image. In this study; hemispherical, four faceted and eight faceted domes are compared with respect to drag force. Furthermore, images are captured by using these manufactured domes. To compare domes effects on images, scenarios are generated and automatic target acquisition algorithm is used.

Vertical drag force acting on intruders of different shapes in granular media

NASA Astrophysics Data System (ADS)

Zaidi, Ali Abbas; Müller, Christoph

2017-06-01

The penetration of large objects into granular media is encountered commonly both in nature (e.g. impacts of meteors and projectiles) and engineering applications (e.g. insertion of tractor blades into sand). The motion of the impacting intruder in granular media is resisted by a granular drag force. In this work, we assess the effect of intruder shape on the granular drag force using discrete element modelling (DEM). The following intruder shapes were modelled: spherical, conical, cylindrical and cubical. We observed that the drag force can be described well by a power-law relationship with intrusion depth, independent of the intruder shape. However, the exponent of the power-law expression increases with increasing "flatness" of the intruder's impacting surface due to an increasing fraction of the granular media affected by the impact of the intruder.

Bioinspired air-retaining nanofur for drag reduction.

PubMed

Kavalenka, Maryna N; Vüllers, Felix; Lischker, Simone; Zeiger, Claudia; Hopf, Andreas; Röhrig, Michael; Rapp, Bastian E; Worgull, Matthias; Hölscher, Hendrik

2015-05-27

Bioinspired nanofur, covered by a dense layer of randomly distributed high aspect ratio nano- and microhairs, possesses superhydrophobic and air-retaining properties. Nanofur is fabricated using a highly scalable hot pulling method in which softened polymer is elongated with a heated sandblasted plate. Here we investigate the stability of the underwater air layer retained by the irregular nanofur topography by applying hydraulic pressure to the nanofur kept underwater, and evaluate the gradual changes in the air-covered area. Furthermore, the drag reduction resulting from the nanofur air retention is characterized by measuring the pressure drop across channels with and without nanofur.

The Space Shuttle Endeavour's drag chute deploys to slow the orbiter as it rolls out on Runway 22 at Edwards Air Force Base at the conclusion of its 14-day STS-111 mission to the International Space Station

NASA Image and Video Library

2002-06-19

The Space Shuttle Endeavour's drag chute deploys to slow the orbiter as it rolls out on Runway 22 at Edwards Air Force Base at the conclusion of its 14-day STS-111 mission to the International Space Station.

Drag and Side Force Reduction for Cyclicsts in Echelon Formation

NASA Astrophysics Data System (ADS)

Nedyalkov, Ivaylo; Cunningham, Alec; Lovell, Adam

2017-11-01

When riding directly behind another cyclist (drafting), a rider can use up to 30% less energy. This technique is often used during competitions, yet drafting in the presence of a cross wind has not been studied extensively. To investigate the effect of side-wind on drafting, 1:11 scale models of two different cyclists were rapid-prototyped and tested in a wind tunnel. The drag and side forces were measured in formations of up to 4 models. The results suggest that there is a significant decrease in both drag and side force when a cyclist is riding in another cyclist's wake. Positioning with no off-stream-wise offset result in the largest reduction of forces. When riding in a group of four cyclists, the second and third cyclist experience the largest force reduction. The size of the leading cyclist affects the reduction of forces, particularly when the leading cyclist is smaller. The results are dependent on the Reynolds number, but appear to be independent at higher Reynolds numbers. Initial full scale tests were conducted at the UNH Flow Physics Facility.

A numerical study of microparticle acoustophoresis driven by acoustic radiation forces and streaming-induced drag forces.

PubMed

Muller, Peter Barkholt; Barnkob, Rune; Jensen, Mads Jakob Herring; Bruus, Henrik

2012-11-21

We present a numerical study of the transient acoustophoretic motion of microparticles suspended in a liquid-filled microchannel and driven by the acoustic forces arising from an imposed standing ultrasound wave: the acoustic radiation force from the scattering of sound waves on the particles and the Stokes drag force from the induced acoustic streaming flow. These forces are calculated numerically in two steps. First, the thermoacoustic equations are solved to first order in the imposed ultrasound field taking into account the micrometer-thin but crucial thermoviscous boundary layer near the rigid walls. Second, the products of the resulting first-order fields are used as source terms in the time-averaged second-order equations, from which the net acoustic forces acting on the particles are determined. The resulting acoustophoretic particle velocities are quantified for experimentally relevant parameters using a numerical particle-tracking scheme. The model shows the transition in the acoustophoretic particle motion from being dominated by streaming-induced drag to being dominated by radiation forces as a function of particle size, channel geometry, and material properties.

Lift vs. drag based mechanisms for vertical force production in the smallest flying insects.

PubMed

Jones, S K; Laurenza, R; Hedrick, T L; Griffith, B E; Miller, L A

2015-11-07

We used computational fluid dynamics to determine whether lift- or drag-based mechanisms generate the most vertical force in the flight of the smallest insects. These insects fly at Re on the order of 4-60 where viscous effects are significant. Detailed quantitative data on the wing kinematics of the smallest insects is not available, and as a result both drag- and lift-based strategies have been suggested as the mechanisms by which these insects stay aloft. We used the immersed boundary method to solve the fully-coupled fluid-structure interaction problem of a flexible wing immersed in a two-dimensional viscous fluid to compare three idealized hovering kinematics: a drag-based stroke in the vertical plane, a lift-based stroke in the horizontal plane, and a hybrid stroke on a tilted plane. Our results suggest that at higher Re, a lift-based strategy produces more vertical force than a drag-based strategy. At the Re pertinent to small insect hovering, however, there is little difference in performance between the two strategies. A drag-based mechanism of flight could produce more vertical force than a lift-based mechanism for insects at Re<5; however, we are unaware of active fliers at this scale. Copyright © 2015 Elsevier Ltd. All rights reserved.

Velocity and Drag Forces on motor-protein-driven Vesicles in Cells

NASA Astrophysics Data System (ADS)

Hill, David; Holzwarth, George; Bonin, Keith

2002-10-01

In cells, vesicle transport is driven by motor proteins such as kinesin and dynein, which use the chemical energy of ATP to overcome drag. Using video-enhanced DIC microscopy at 8 frames/s, we find that vesicles in PC12 neurites move with an average velocity of 1.52 0.66 μm/s. The drag force and work required for such steady movement, calculated from Stokes' Law and the zero-frequency viscosity of the cytoplasm, suggest that multiple motors are required to move one vesicle. In buffer, single kinesin molecules move beads in 8-nm steps, each step taking only 50 μs [1]. The effects of such quick steps in cytoplasm, using viscoelastic moduli of COS7 cells, are small [2]. To measure drag forces more directly, we are using B-field-driven magnetic beads in PC12 cells to mimic kinesin-driven vesicles. [1] Nishiyama, M. et al., Nat. Cell Bio. 3, 425-428 (2001). [2] Holzwarth, Bonin, and Hill, Biophys J 82, 1784-1790 (2002).

The effect of caster wheel diameter and mass distribution on drag forces in manual wheelchairs.

PubMed

Zepeda, Rene; Chan, Franco; Sawatzky, Bonita

2016-01-01

This study proposes a way to reduce energy losses in the form of rolling resistance friction during manual wheelchair propulsion by increasing the size of the front caster wheels and adjusting the weight distribution. Drag tests were conducted using a treadmill and a force transducer. Three different casters diameter (4 in., 5 in., and 6 in.) and six different mass distribution combinations (based on percentage of total weight on the caster wheels) were studied. A two-way analysis of variance test was performed to compare caster size and weight distribution contribution with drag force of an ultralight wheelchair. The 4 in. caster contributed significantly more drag, but only when weight was 40% or greater over the casters. Weight distribution contributed more to drag regardless of the casters used.

Comparison of gimbal approaches to decrease drag force and radar cross sectional area in missile application

NASA Astrophysics Data System (ADS)

Sakarya, Doǧan Uǧur

2017-05-01

Drag force effect is an important aspect of range performance in missile applications especially for long flight time. However, old fashioned gimbal approaches force to increase missile diameter. This increase has negative aspect of rising in both drag force and radar cross sectional area. A new gimbal approach was proposed recently. It uses a beam steering optical arrangement. Therefore, it needs less volume envelope for same field of regard and same optomechanical assembly than the old fashioned gimbal approaches. In addition to longer range performance achieved with same fuel in the new gimbal approach, this method provides smaller cross sectional area which can be more invisible in enemies' radar. In this paper, the two gimbal approaches - the old fashioned one and the new one- are compared in order to decrease drag force and radar cross sectional area in missile application. In this study; missile parameters are assumed to generate gimbal and optical design parameters. Optical design is performed according to these missile criteria. Two gimbal configurations are designed with respect to modeled missile parameters. Also analyzes are performed to show decreased drag force and radar cross sectional area in the new approach for comparison.

Lateral-drag propulsion forces induced by anisotropy.

PubMed

Nefedov, Igor S; Rubi, J Miguel

2017-07-21

We predict the existence of lateral drag forces near the flat surface of an absorbing slab made of an anisotropic material. The forces originate from the fluctuations of the electromagnetic field, when the anisotropy axis of the material forms a certain angle with the surface. In this situation, the spatial spectra of the fluctuating electromagnetic fields becomes asymmetric, different for positive and negative transverse wave vectors components. Differently from the case of van der Waals interactions in which the forward-backward symmetry is broken due to the particle movement, in our case the lateral motion results merely from the anisotropy of the slab. This new effect, of particular significance in hyperbolic materials, could be used for the manipulation of nanoparticles.

Drag forces of natural trees of different size: experiments in a towing tank

NASA Astrophysics Data System (ADS)

Jalonen, Johanna; Järvelä, Juha

2013-04-01

Reliable estimation of hydraulic resistance is of great importance in practical applications such as river and wetland restoration as well as flood prediction and management. Parameters describing riparian vegetation need to be physically sound and readily measurable. For these purposes, several researchers have studied the hydraulic resistance in flumes with living and artificial plants both in arrays and with isolated plants. However, due to the restrictions of flume size the experiments are often conducted with parts of trees, twigs or branches. Consequently, it is not clear how the size (parts of trees or small trees vs. full scale trees) affects the hydraulic resistance. We conducted direct drag force measurements for 23 tree individuals of different heights (0.9 m - 3.5 m) in a towing tank. The investigated species were Common Alder (Alnus glutinosa), Goat Willow (Salix caprea), Silver Birch (Betula pendula) and White Birch (Betula pubescens). The forces were measured at velocity ranges of 0.1-2.5 m/s and 0.1-2.0 m/s both in leafy and leafless conditions, respectively. The measurement system consisted of three load cells measuring the main flow direction. Two different load cell setups were used depending on the size of the specimen to allow for accurate force measurement. For the smaller trees the load cells were replaced with more sensitive sensors, and the resulting ranges of the load cells were from 1 to 1000 N and from 0.1 to 100 N. Frontal and side projected areas and bending of the specimens were recorded during the measurements using submerged video cameras. For all specimens, wet and dry biomass, projected area in still air, and one-sided leaf area were determined. In order to construct a 3D-model of the trees, the specimens were laser scanned from three directions with a terrestrial laser scanner (TLS). The resulting point cloud had a millimeter resolution, and provided detailed information about the plant characteristics, such as leaf area

Erosion in radial inflow turbines. Volume 2: Balance of centrifugal and radial drag forces on erosive particles

NASA Technical Reports Server (NTRS)

Clevenger, W. B., Jr.; Tabakoff, W.

1974-01-01

The particle motion in two-dimensional free and forced inward flowing vortices is considered. A particle in such a flow field experiences a balance between the aerodynamic drag forces that tend to drive erosive particles toward the axis, and centrifugal forces that prevent these particles from traveling toward the axis. Results predict that certain sizes of particles will achieve a stable orbit about the turbine axis in the inward flowing free vortex. In this condition, the radial drag force is equal to the centrifugal force. The sizes of particles that will achieve a stable orbit is shown to be related to the gas flow velocity diagram at a particular radius. A second analysis yields a description of particle sizes that will experience a centrifugal force that is greater than the radial component of the aerodynamic drag force for a more general type of particle motion.

Typhoon air-sea drag coefficient in coastal regions

NASA Astrophysics Data System (ADS)

Zhao, Zhong-Kuo; Liu, Chun-Xia; Li, Qi; Dai, Guang-Feng; Song, Qing-Tao; Lv, Wei-Hua

2015-02-01

The air-sea drag during typhoon landfalls is investigated for a 10 m wind speed as high as U10 ≈ 42 m s-1, based on multilevel wind measurements from a coastal tower located in the South China Sea. The drag coefficient (CD) plotted against the typhoon wind speed is similar to that of open ocean conditions; however, the CD curve shifts toward a regime of lower winds, and CD increases by a factor of approximately 0.5 relative to the open ocean. Our results indicate that the critical wind speed at which CD peaks is approximately 24 m s-1, which is 5-15 m s-1 lower than that from deep water. Shoaling effects are invoked to explain the findings. Based on our results, the proposed CD formulation, which depends on both water depth and wind speed, is applied to a typhoon forecast model. The forecasts of typhoon track and surface wind speed are improved. Therefore, a water-depth-dependence formulation of CD may be particularly pertinent for parameterizing air-sea momentum exchanges over shallow water.

Concurrent field measurements of turbulent velocities, plant reconfiguration and drag forces on Ranunculus penicillatus

NASA Astrophysics Data System (ADS)

Paul, Maike; Thomas, Robert E.; Keevil, Gareth M.

2013-04-01

In lowland rivers, seasonal patterns of in-stream macrophyte growth and decay have significant implications for flood risk. For a given discharge, flood risk is increased when dense macrophyte canopies reduce flow areas, increase blockage ratios and alter reach-scale roughness values. These factors combine and can increase the flow depth. Conversely, submerged vegetation is exposed to drag forces exerted by the flow, which may be sufficient to damage limbs or dislodge plants. The classical drag equation suggests that the force exerted by fluid flows upon submerged vegetation is a function of the fluid properties, the projected area of the vegetation, and the square of the flow velocity. However, very few studies have simultaneously monitored all of these parameters, resulting in significant uncertainty in the estimation of the coefficient that relates these parameters to the drag force and also the related roughness parameters that control the flow depth for a given discharge. To our knowledge, this study presents the first concurrent field measurements of turbulent velocities, plant reconfigurations and drag forces acting on Ranunculus penicillatus ssp. pseudofluitans (Syme) S.D.Webster. Measurements were undertaken in an artificially straightened reach of the chalk-bed River Wylye, near Longbridge Deverill, Wiltshire, UK. The reach is 5.7 m wide and during measurements there was a mean flow depth of 0.28 m and an average discharge of 0.28 m³s-1. The reach is cleared of vegetation up to three times a year for flood defence purposes, but Ranunculus p. grows back within several weeks. Measurements were carried out after re-growth, when plants were fully developed with a mean length of 0.75 m and on average 6 nodes along the stem. The distances between the nodes increased from the base towards the tip and each node produced a capillary leaf, sometimes in conjunction with a branch. Floating leaves and flowers were not present. Plants were attached to a custom

Catenaries in Drag

NASA Astrophysics Data System (ADS)

Chakrabarti, Brato; Hanna, James

2014-11-01

Dynamical equilibria of towed cables and sedimenting filaments have been the targets of much numerical work; here, we provide analytical expressions for the configurations of a translating and axially moving string subjected to a uniform body force and local, linear, anisotropic drag forces. Generically, these configurations comprise a five-parameter family of planar shapes determined by the ratio of tangential (axial) and normal drag coefficients, the angle between the translational velocity and the body force, the relative magnitudes of translational and axial drag forces with respect to the body force, and a scaling parameter. This five-parameter family of shapes is, in fact, a degenerate six-parameter family of equilibria in which inertial forces rescale the tension in the string without affecting its shape. Each configuration is represented by a first order dynamical system for the tangential angle of the body. Limiting cases include the dynamic catenaries with or without drag, and purely sedimenting or towed strings.

THE GRAVITATIONAL DRAG FORCE ON AN EXTENDED OBJECT MOVING IN A GAS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bernal, Cristian G.; Sánchez-Salcedo, F. J.

2013-09-20

Using axisymmetrical numerical simulations, we revisit the gravitational drag felt by a gravitational Plummer sphere with mass M and core radius R{sub s} moving at constant velocity V{sub 0} through a background homogeneous medium of adiabatic gas. Since the potential is non-diverging, there is no gas removal due to accretion. When R{sub s} is larger than the Bondi radius R{sub B} , the perturbation is linear at every point and the drag force is well fitted by the time-dependent Ostriker's formula with r{sub min} = 2.25R{sub s} , where r{sub min} is the minimum impact parameter in the Coulomb logarithm.more » In the deep nonlinear supersonic regime (R{sub s} << R{sub B} ), the minimum radius is no longer related to R{sub s} but to R{sub B} . We find r{sub min}=3.3M{sup -2.5}R{sub B} for Mach numbers of the perturber between 1.5 and 4, although r{sub min}= 2M{sup -2}R{sub B}=2GM/V{sup 2}{sub 0} also provides a good fit at M>2. As a consequence, the drag force does not depend sensitively on the nonlinearity parameter A, defined as R{sub B} /R{sub s} , for A values larger than a certain critical value A{sub cr}. We show that our generalized Ostriker's formula for the drag force is more accurate than the formula suggested by Kim and Kim.« less

High accuracy satellite drag model (HASDM)

NASA Astrophysics Data System (ADS)

Storz, Mark F.; Bowman, Bruce R.; Branson, Major James I.; Casali, Stephen J.; Tobiska, W. Kent

The dominant error source in force models used to predict low-perigee satellite trajectories is atmospheric drag. Errors in operational thermospheric density models cause significant errors in predicted satellite positions, since these models do not account for dynamic changes in atmospheric drag for orbit predictions. The Air Force Space Battlelab's High Accuracy Satellite Drag Model (HASDM) estimates and predicts (out three days) a dynamically varying global density field. HASDM includes the Dynamic Calibration Atmosphere (DCA) algorithm that solves for the phases and amplitudes of the diurnal and semidiurnal variations of thermospheric density near real-time from the observed drag effects on a set of Low Earth Orbit (LEO) calibration satellites. The density correction is expressed as a function of latitude, local solar time and altitude. In HASDM, a time series prediction filter relates the extreme ultraviolet (EUV) energy index E10.7 and the geomagnetic storm index ap, to the DCA density correction parameters. The E10.7 index is generated by the SOLAR2000 model, the first full spectrum model of solar irradiance. The estimated and predicted density fields will be used operationally to significantly improve the accuracy of predicted trajectories for all low-perigee satellites.

Surface adhesive forces: a metric describing the drag-reducing effects of superhydrophobic coatings.

PubMed

Cheng, Mengjiao; Song, Mengmeng; Dong, Hongyu; Shi, Feng

2015-04-08

Nanomaterials with superhydrophobic properties are promising as drag-reducing coatings. However, debates regarding whether superhydrophobic surfaces are favorable for drag reduction require further clarification. A quantified water adhesive force measurement is proposed as a metric and its effectiveness demonstrated using three typical superhydrophobic coatings on model ships with in situ sailing tests. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Thickened boundary layer theory for air film drag reduction on a van body surface

NASA Astrophysics Data System (ADS)

Xie, Xiaopeng; Cao, Lifeng; Huang, Heng

2018-05-01

To elucidate drag reduction mechanism on a van body surface under air film condition, a thickened boundary layer theory was proposed and a frictional resistance calculation model of the van body surface was established. The frictional resistance on the van body surface was calculated with different parameters of air film thickness. In addition, the frictional resistance of the van body surface under the air film condition was analyzed by computational fluid dynamics (CFD) simulation and different air film states that influenced the friction resistance on the van body surface were discussed. As supported by the CFD simulation results, the thickened boundary layer theory may provide reference for practical application of air film drag reduction on a van body surface.

Lift and drag forces on an inclined plow moving over a granular surface.

PubMed

Percier, Baptiste; Manneville, Sebastien; McElwaine, Jim N; Morris, Stephen W; Taberlet, Nicolas

2011-11-01

We studied the drag and lift forces acting on an inclined plate while it is dragged on the surface of a granular media, both in experiment and in numerical simulation. In particular, we investigated the influence of the horizontal velocity of the plate and its angle of attack. We show that a steady wedge of grains is moved in front of the plow and that the lift and drag forces are proportional to the weight of this wedge. These constants of proportionality vary with the angle of attack but not (or only weakly) on the velocity. We found a universal effective friction law that accounts for the dependence on all the above-mentioned parameters. The stress and velocity fields are calculated from the numerical simulations and show the existence of a shear band under the wedge and that the pressure is nonhydrostatic. The strongest gradients in stress and shear occur at the base of the plow where the dissipation rate is therefore highest.

Significant and stable drag reduction with air rings confined by alternated superhydrophobic and hydrophilic strips

PubMed Central

Hu, Haibao; Wen, Jun; Bao, Luyao; Jia, Laibing; Song, Dong; Song, Baowei; Pan, Guang; Scaraggi, Michele; Dini, Daniele; Xue, Qunji; Zhou, Feng

2017-01-01

Superhydrophobic surfaces have the potential to reduce the viscous drag of liquids by significantly decreasing friction at a solid-liquid interface due to the formation of air layers between solid walls and interacting liquids. However, the trapped air usually becomes unstable due to the finite nature of the domain over which it forms. We demonstrate for the first time that a large surface energy barrier can be formed to strongly pin the three-phase contact line of air/water/solid by covering the inner rotor of a Taylor-Couette flow apparatus with alternating superhydrophobic and hydrophilic circumferential strips. This prevents the disruption of the air layer, which forms stable and continuous air rings. The drag reduction measured at the inner rotor could be as much as 77.2%. Moreover, the air layers not only significantly reduce the strength of Taylor vortexes but also influence the number and position of the Taylor vortex pairs. This has strong implications in terms of energy efficiency maximization for marine applications and reduction of drag losses in, for example, fluid transport in pipelines and carriers. PMID:28879234

Physically-based modeling of drag force caused by natural woody vegetation

NASA Astrophysics Data System (ADS)

Järvelä, J.; Aberle, J.

2014-12-01

Riparian areas and floodplains are characterized by woody vegetation, which is an essential feature to be accounted for in many hydro-environmental models. For applications including flood protection, river restoration and modelling of sediment processes, there is a need to improve the reliability of flow resistance estimates. Conventional methods such as the use of lumped resistance coefficients or simplistic cylinder-based drag force equations can result in significant errors, as these methods do not adequately address the effect of foliage and reconfiguration of flexible plant parts under flow action. To tackle the problem, physically-based methods relying on objective and measurable vegetation properties are advantageous for describing complex vegetation. We have conducted flume and towing tank investigations with living and artificial plants, both in arrays and with isolated plants, providing new insight into advanced parameterization of natural vegetation. The stem, leaf and total areas of the trees confirmed to be suitable characteristic dimensions for estimating flow resistance. Consequently, we propose the use of leaf area index and leaf-to-stem-area ratio to achieve better drag force estimates. Novel remote sensing techniques including laser scanning have become available for effective collection of the required data. The benefits of the proposed parameterization have been clearly demonstrated in our newest experimental studies, but it remains to be investigated to what extent the parameter values are species-specific and how they depend on local habitat conditions. The purpose of this contribution is to summarize developments in the estimation of vegetative drag force based on physically-based approaches as the latest research results are somewhat dispersed. In particular, concerning woody vegetation we seek to discuss three issues: 1) parameterization of reconfiguration with the Vogel exponent; 2) advantage of parameterizing plants with the leaf area

Rotating flexible drag mill

DOEpatents

Pepper, W.B.

1984-05-09

A rotating parachute for decelerating objects travelling through atmosphere at subsonic or supersonic deployment speeds includes a circular canopy having a plurality of circumferentially arranged flexible panels projecting radially from a solid central disk. A slot extends radially between adjacent panels to the outer periphery of the canopy. Upon deployment, the solid disk diverts air radially to rapidly inflate the panels into a position of maximum diameter. Air impinging on the panels adjacent the panel slots rotates the parachute during its descent. Centrifugal force flattens the canopy into a constant maximum diameter during terminal descent for maximum drag and deceleration.

High accuracy satellite drag model (HASDM)

NASA Astrophysics Data System (ADS)

Storz, M.; Bowman, B.; Branson, J.

The dominant error source in the force models used to predict low perigee satellite trajectories is atmospheric drag. Errors in operational thermospheric density models cause significant errors in predicted satellite positions, since these models do not account for dynamic changes in atmospheric drag for orbit predictions. The Air Force Space Battlelab's High Accuracy Satellite Drag Model (HASDM) estimates and predicts (out three days) a dynamically varying high-resolution density field. HASDM includes the Dynamic Calibration Atmosphere (DCA) algorithm that solves for the phases and amplitudes of the diurnal, semidiurnal and terdiurnal variations of thermospheric density near real-time from the observed drag effects on a set of Low Earth Orbit (LEO) calibration satellites. The density correction is expressed as a function of latitude, local solar time and altitude. In HASDM, a time series prediction filter relates the extreme ultraviolet (EUV) energy index E10.7 and the geomagnetic storm index a p to the DCA density correction parameters. The E10.7 index is generated by the SOLAR2000 model, the first full spectrum model of solar irradiance. The estimated and predicted density fields will be used operationally to significantly improve the accuracy of predicted trajectories for all low perigee satellites.

Response spectrum method for extreme wave loading with higher order components of drag force

NASA Astrophysics Data System (ADS)

Reza, Tabeshpour Mohammad; Mani, Fatemi Dezfouli; Ali, Dastan Diznab Mohammad; Saied, Mohajernasab; Saied, Seif Mohammad

2017-03-01

Response spectra of fixed offshore structures impacted by extreme waves are investigated based on the higher order components of the nonlinear drag force. In this way, steel jacket platforms are simplified as a mass attached to a light cantilever cylinder and their corresponding deformation response spectra are estimated by utilizing a generalized single degree of freedom system. Based on the wave data recorded in the Persian Gulf region, extreme wave loading conditions corresponding to different return periods are exerted on the offshore structures. Accordingly, the effect of the higher order components of the drag force is considered and compared to the linearized state for different sea surface levels. When the fundamental period of the offshore structure is about one third of the main period of wave loading, the results indicate the linearized drag term is not capable of achieving a reliable deformation response spectrum.

Air-Induced Drag Reduction at High Reynolds Numbers: Velocity and Void Fraction Profiles

NASA Astrophysics Data System (ADS)

Elbing, Brian; Mäkiharju, Simo; Wiggins, Andrew; Dowling, David; Perlin, Marc; Ceccio, Steven

2010-11-01

The injection of air into a turbulent boundary layer forming over a flat plate can reduce the skin friction. With sufficient volumetric fluxes an air layer can separate the solid surface from the flowing liquid, which can produce drag reduction in excess of 80%. Several large scale experiments have been conducted at the US Navy's Large Cavitation Channel on a 12.9 m long flat plate model investigating bubble drag reduction (BDR), air layer drag reduction (ALDR) and the transition between BDR and ALDR. The most recent experiment acquired phase velocities and void fraction profiles at three downstream locations (3.6, 5.9 and 10.6 m downstream from the model leading edge) for a single flow speed (˜6.4 m/s). The profiles were acquired with a combination of electrode point probes, time-of-flight sensors, Pitot tubes and an LDV system. Additional diagnostics included skin-friction sensors and flow-field image visualization. During this experiment the inlet flow was perturbed with vortex generators immediately upstream of the injection location to assess the robustness of the air layer. From these, and prior measurements, computational models can be refined to help assess the viability of ALDR for full-scale ship applications.

Measuring the Effects of Lift and Drag on Projectile Motion

ERIC Educational Resources Information Center

Cross, Rod

2012-01-01

The trajectory of a projectile through the air is affected both by gravity and by aerodynamic forces. The latter forces can conveniently be ignored in many situations, even when they are comparatively large. For example, if a 145-g, 74-mm diameter baseball is pitched at 40 ms[superscript -1] (89.5 mph), it experiences a drag force of about 1.5 N.…

Extending the frequency of response of lightly damped second order systems: Application to the drag force anemometer

NASA Technical Reports Server (NTRS)

Fralick, G. C.

1982-01-01

It is shown that a conventional electronic frequency compensator does not provide adequate compensation near the resonant frequency of a lightly damped second order system, such as the drag force anemometer. The reason for this is discussed, and a simple circuit modification is presented which overcomes the difficulty. The improvement is shown in theoretical frequency response curves as well as in the experimental results from some typical drag force anemometers.

Liquid film drag out in the presence of molecular forces

NASA Astrophysics Data System (ADS)

Schmidhalter, I.; Cerro, R. L.; Giavedoni, M. D.; Saita, F. A.

2013-03-01

From a practical as well as a conceptual point of view, one of the most interesting problems of physicochemical hydrodynamics is the drag out of a liquid film by a moving solid out of a pool of liquid. The basic problem, sometimes denoted the Landau-Levich problem [L. Landau and B. Levich, "Dragging of a liquid by a moving plate," Acta Physicochim. USSR 17, 42-54 (1942)], involves an interesting blend of capillary and viscous forces plus a matching of the static solution for capillary rise with a numerical solution of the film evolution equation, neglecting gravity, on the downstream region of the flow field. The original solution describes experimental data for a wide range of Capillary numbers but fails to match results for large and very small Capillary numbers. Molecular level forces are introduced to create an augmented version of the film evolution equation to show the effect of van der Waals forces at the lower range of Capillary numbers. A closed form solution for static capillary rise, including molecular forces, was matched with a numerical solution of the augmented film evolution equation in the dynamic meniscus region. Molecular forces do not sensibly modify the static capillary rise region, since film thicknesses are larger than the range of influence of van der Waals forces, but are determinant in shaping the downstream dynamic meniscus of the very thin liquid films. As expected, a quantitatively different level of disjoining pressure for different values of molecular constants remains in the very thin liquid film far downstream. Computational results for a wide range of Capillary numbers and Hamaker constants show a clear transition towards a region where the film thickness becomes independent of the coating speed.

Measurements of drag and lift on smooth balls in flight

NASA Astrophysics Data System (ADS)

Cross, Rod; Lindsey, Crawford

2017-07-01

Measurements are presented on the drag and lift coefficients for three relatively smooth balls launched in air and tracked with two cameras separated horizontally by 6.4 m. The ball spin was varied in order to investigate whether the Magnus force would increase or decrease when the ball spin was increased. For one ball, the Magnus force increased. For another ball, the Magnus force decreased almost to zero after reaching a maximum. For the third ball, the Magnus force was negative at low ball spins and positive at high ball spins. For one of the balls, the ball spin increased with time as it travelled through the air.

Reducing Water/Hull Drag By Injecting Air Into Grooves

NASA Technical Reports Server (NTRS)

Reed, Jason C.; Bushnell, Dennis M.; Weinstein, Leonard M.

1991-01-01

Proposed technique for reduction of friction drag on hydrodynamic body involves use of grooves and combinations of surfactants to control motion of layer on surface of such body. Surface contains many rows of side-by-side, evenly spaced, longitudinal grooves. Dimensions of grooves and sharpnesses of tips in specific case depends on conditions of flow about vessel. Requires much less air than does microbubble-injection method.

STS-66 landing at Edwards Air Force Base

NASA Image and Video Library

1994-11-14

STS066-S-039 (14 November 1994) --- The drag chute is fully deployed as the Space Shuttle Atlantis heads toward a stop at Edwards Air Force Base in southern California, ending a successful 10 day, 22 hour and 34 minute space mission. Landing occurred at 7:34 a.m. (PST), November 14, 1994. Onboard were astronauts Donald R. McMonagle, commander; Curtis L. Brown, Jr., pilot; Ellen S. Ochoa, payload commander; Scott E. Parazynski and Joseph R. Tanner, both mission specialists, along with European Space Agency (ESA) mission specialist Jean-Francois Clervoy. The crew supported the Atmospheric Laboratory for Applications and Science (ATLAS-3) mission.

Air Force Research Laboratory, Edwards Air Force Base, CA

DTIC Science & Technology

2011-06-27

Air Force Research Laboratory (AFMC) AFRL /RZS 1 Ara Road Edwards AFB CA 93524-7013 AFRL -RZ-ED-VG-2011-269 9...SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR’S ACRONYM(S) Air Force Research Laboratory (AFMC) AFRL /RZS 11. SPONSOR...Form 298 (Rev. 8-98) Prescribed by ANSI Std. 239.18 Air Force Research Laboratory Ed d Ai F B CA Col Mike Platt war s r orce

Assessing the failure of continuum formula for solid-solid drag force using discrete element method in large size ratios

NASA Astrophysics Data System (ADS)

Jalali, Payman; Hyppänen, Timo

2017-06-01

In loose or moderately-dense particle mixtures, the contact forces between particles due to successive collisions create average volumetric solid-solid drag force between different granular phases (of different particle sizes). The derivation of the mathematical formula for this drag force is based on the homogeneity of mixture within the calculational control volume. This assumption especially fails when the size ratio of particles grows to a large value of 10 or greater. The size-driven inhomogeneity is responsible to the deviation of intergranular force from the continuum formula. In this paper, we have implemented discrete element method (DEM) simulations to obtain the volumetric mean force exchanged between the granular phases with the size ratios greater than 10. First, the force is calculated directly from DEM averaged over a proper time window. Second, the continuum formula is applied to calculate the drag forces using the DEM quantities. We have shown the two volumetric forces are in good agreement as long as the homogeneity condition is maintained. However, the relative motion of larger particles in a cloud of finer particles imposes the inhomogeneous distribution of finer particles around the larger ones. We have presented correction factors to the volumetric force from continuum formula.

Projectile Motion with a Drag Force: Were the Medievals Right After All?

ERIC Educational Resources Information Center

La Rocca, Paola; Riggi, Francesco

2009-01-01

An educational and historical study of the projectile motion with drag forces dependent on speed shows, by simple results, that trajectories quite similar to those depicted before the Galilean era may be obtained with a realistic choice of quantities involved. Numerical simulations of the trajectory in space and velocity coordinates help us to…

Sharp Transition in the Lift Force of a Fluid Flowing Past Nonsymmetrical Obstacles: Evidence for a Lift Crisis in the Drag Crisis Regime.

PubMed

Bot, Patrick; Rabaud, Marc; Thomas, Goulven; Lombardi, Alessandro; Lebret, Charles

2016-12-02

Bluff bodies moving in a fluid experience a drag force which usually increases with velocity. However in a particular velocity range a drag crisis is observed, i.e., a sharp and strong decrease of the drag force. This counterintuitive result is well characterized for a sphere or a cylinder. Here we show that, for an object breaking the up-down symmetry, a lift crisis is observed simultaneously to the drag crisis. The term lift crisis refers to the fact that at constant incidence the time-averaged transverse force, which remains small or even negative at low velocity, transitions abruptly to large positive values above a critical flow velocity. This transition is characterized from direct force measurements as well as from change in the velocity field around the obstacle.

Studies of Aerodynamic Drag.

DTIC Science & Technology

1982-12-01

31. Strouhal number vs Reynolds number - Effect of Wind tunnel Blockage. 150- P ecrit 100- 50k- o present d Qta o Mitry (1977) --Shair et ati (1963) 0...forces measured by the balance. 4.12 Final Tests A comprehensive set of drag measurements was taken with the new drag plates, the drag plates being

Self-propulsion against a moving membrane: Enhanced accumulation and drag force

NASA Astrophysics Data System (ADS)

Marini Bettolo Marconi, U.; Sarracino, A.; Maggi, C.; Puglisi, A.

2017-09-01

Self-propulsion (SP) is a main feature of active particles (AP), such as bacteria or biological micromotors, distinguishing them from passive colloids. A renowned consequence of SP is accumulation at static interfaces, even in the absence of hydrodynamic interactions. Here we address the role of SP in the interaction between AP and a moving semipermeable membrane. In particular, we implement a model of noninteracting AP in a channel crossed by a partially penetrable wall, moving at a constant velocity c . With respect to both the cases of passive colloids with c >0 and AP with c =0 , the AP with finite c show enhancement of accumulation in front of the obstacle and experience a largely increased drag force. This effect is understood in terms of an effective potential localised at the interface between particles and membrane, of height proportional to c τ /ξ , where τ is the AP's reorientation time and ξ the width characterizing the surface's smoothness (ξ →0 for hard core obstacles). An approximate analytical scheme is able to reproduce the observed density profiles and the measured drag force, in very good agreement with numerical simulations. The effects discussed here can be exploited for automatic selection and filtering of AP with desired parameters.

Air Force Leadership Diversity

DTIC Science & Technology

2017-04-06

AIR WAR COLLEGE AIR UNIVERSITY AIR FORCE LEADERSHIP DIVERSITY by G. Hall Sebren, Jr., Col, USAF A Research Report Submitted to the...both in HAF/A8 (Strategic Plans and Programs). iv Abstract The Air Force is not drawing upon its full talent pool for leadership in its...promotions boards, but the Air Force promotion system itself is not the problem. Leadership decisions to only allow officers selected for promotion from

The Effect of Turbulence on the Drag of Flat Plates

NASA Technical Reports Server (NTRS)

Schubauer, G B; Dryden, H L

1937-01-01

in determining the effect of turbulence on the forces exerted on bodies in the air stream of a wind tunnel, it is commonly assumed that the indications of the standard Pitot-static tube used to determine the air speed are not dependent on the turbulence. To investigate the truth of this assumption, the drag of a normally exposed flat plate, the difference in pressure between the front and rear of a thin circular disk, the rate of rotation of a vane anemometer, and the pressure developed by a standard Pitot-static tube were measured in an air stream for several conditions of turbulence. The results may be interpreted as indicating that there is no appreciable effect of turbulence on the vane anemometer and the standard pitot-static tube, but that there is small effect on the drag of a flat plate and the pressure difference between front and rear of a disk.

Progress towards a Drag-free SmallSat

NASA Astrophysics Data System (ADS)

Saraf, Shailendhar

The net force acting on a drag-free satellite is purely gravitational as all other forces, mainly atmospheric drag and solar radiation pressure, are canceled out. In order to achieve this, a free floating reference (test mass) inside the satellite is shielded against all forces but gravity and a system of thrusters is commanded by a control algorithm such that the relative displacement between the reference and the satellite stays constant. The main input to that control algorithm is the output of a sensor which measures the relative displacement between the satellite and the test mass. Internal disturbance forces such as electrostatic or magnetic forces cannot be canceled out his way and have to be minimized by a careful design of the satellite. A drag-free technology package is under development at Stanford since 2004. It includes an optical displacement sensor to measure the relative position of the test mass inside the satellite, a caging mechanism to lock the test mass during launch, a UV LED based charge management system to minimize the effect of electrostatic forces, a thermal enclosure, and the drag-free control algorithms. Possible applications of drag-free satellites in fundamental physics (Gravity Probe B, LISA), geodesy (GOCE), and navigation (TRIAD I). In this presentation we will highlight the progress of the technology development towards a drag-free mission. The planned mission on a SaudiSat bus will demonstrate drag-free technology on a small spacecraft at a fraction of the cost of previous drag-free missions. The target acceleration noise is 10-12 m/sec2. With multiple such satellites a GRACE-like mission with improved sensitivity and potentially improved spatial and temporal resolution can be achieved.

Experimental study of the effect of drag reducing agent on pressure drop and thermal efficiency of an air cooler

NASA Astrophysics Data System (ADS)

Peyghambarzadeh, S. M.; Hashemabadi, S. H.; Saffarian, H.; Shekari, F.

2016-01-01

Effect of polymeric drag reduction agents (DRAs) on pressure drop and heat transfer was studied. Aqueous solutions of carboxy methyl cellulose were used inside an air-finned heat exchanger. Despite the previous studies which indicated the importance of drag reduction just in turbulent flow, results of this study in laminar flow indicated that the addition of DRA increases drag reduction, and decreases the overall heat transfer coefficient.

State dragging using the quantum Zeno effect

NASA Astrophysics Data System (ADS)

Hacohen-Gourgy, Shay; Martin, Leigh; GarcíA-Pintos, Luis Pedro; Dressel, Justin; Siddiqi, Irfan

The quantum Zeno effect is the suppression of Hamiltonian evolution by continuous measurement. It arises as a consequence of the quantum back-action pushing the state towards an eigenstate of the measurement operator. Rotating the operator at a rate much slower than the measurement rate will effectively drag the state with it. We use our recently developed scheme, which enables dynamic control of the measurement operator, to demonstrate this dragging effect on a superconducting transmon qubit. Since the system is continuously measured, the deterministic trajectory can be monitored, and quantum jumps can be detected in real-time. Furthermore, we perform this with two observables that are set to be either commuting or non-commuting, demonstrating new quantum dynamics. This work was supported by the Army Research Office and the Air Force Research Laboratory.

Air Force TV

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A lone desert Joshua tree greeted the arrival of Space Shuttle Endeavour at Edwards Air Force Base,

NASA Technical Reports Server (NTRS)

2001-01-01

A lone desert Joshua tree greeted the arrival of Space Shuttle Endeavour at Edwards Air Force Base, California, May 1, 2001. A large drag chute helped slow Endeavour on the runway. After mounting the shuttle on a converted 747 airliner at NASA's Dryden Flight Research Center, Endeavour will be carried back to the Kennedy Space Center for its next mission. Weather in Florida necessitated landing in California.

Reconfiguration parameters for drag of flexible cylindrical elements

NASA Astrophysics Data System (ADS)

John, Chapman; Wilson, Bruce; Gulliver, John

2015-11-01

This presentation compares parameters that characterize reconfiguration effects on flow resistance and drag. The drag forces occurring on flexible bluff bodies are different from the drag occurring on rigid bluff bodies due to reconfiguration. Drag force data, collected using a torque sensor in a flume, for simple cylindrical obstructions of the same shape and size but with different flexibility is used to fit drag parameters. The key parameter evaluated is a reference velocity factor u to account for drag reduction due to reconfiguration, similar to a Vogel exponent. Our equations preserves the traditional exponent of the drag relationship, but places a factor onto the drag coefficient for flexible elements, rather than a Vogel exponent arrangement applied to the flow velocity. Additionally we relate the reference velocity factor u to the modulus of elasticity of the material through the Cauchy Number. The use of a reference velocity factor u in place of a Vogel exponent appears viable to account for how the drag forces are altered by reconfiguration. The proposed formulation for drag reduction is more consistently estimated for the range of flexibilities in this study. Unfortunately, the mechanical properties of vegetation are not often readily available for reconfiguration relationships to the elastic modulus of vegetation to be of immediate practical use.

78 FR 49484 - Exchange of Air Force Real Property for Non-Air Force Real Property

Federal Register 2010, 2011, 2012, 2013, 2014

2013-08-14

... DEPARTMENT OF DEFENSE Department of Air Force Exchange of Air Force Real Property for Non-Air Force Real Property SUMMARY: Notice identifies excess Federal real property under administrative jurisdiction of the United States Air Force it intends to exchange for real property not currently owned by the...

Evaluation of Skin Friction Drag for Liner Applications in Aircraft

NASA Technical Reports Server (NTRS)

Gerhold, Carl H.; Brown, Martha C.; Jasinski, Christopher M.

2016-01-01

A parameter that is gaining significance in the evaluation of acoustic liner performance is the skin friction drag induced by air flow over the liner surface. Estimates vary widely regarding the amount of drag the liner induces relative to a smooth wall, from less than a 20% increase to nearly 100%, and parameters such as face sheet perforate hole diameter, percent open area, and sheet thickness are expected to figure prominently in the skin friction drag. Even a small increase in liner drag can impose an economic penalty, and current research is focused on developing 'low drag' liner concepts, with the goal being to approach the skin friction drag of a smooth wall. The issue of skin friction drag takes on greater significance as airframe designers investigate the feasibility of putting sound absorbing liners on the non-lifting surfaces of the wings and fuselage, for the purpose of reducing engine noise reflected and scattered toward observers on the ground. Researchers at the NASA Langley Research Center have embarked on investigations of liner skin friction drag with the aims of: developing a systematic drag measurement capability, establishing the drag of current liners, and developing liners that produce reduced drag without compromising acoustic performance. This paper discusses the experimental procedures that have been developed to calculate the drag coefficient based on the change in momentum thickness and the companion research program being carried out to measure the drag directly using a force balance. Liner samples that are evaluated include a solid wall with known roughness and conventional liners with perforated facesheets of varying hole diameter and percent open area.

Flow drag and heat transfer characteristics of drag-reducing nanofluids with CuO nanoparticles

NASA Astrophysics Data System (ADS)

Wang, Ping-Yang; Wang, Xue-Jiao; Liu, Zhen-Hua

2017-02-01

A new kind of aqueous CuO nanofluid with drag-reducing performance was developed. The new working fluid was an aqueous CTAC (cetyltrimethyl ammonium chloride) solution with CuO nanoparticles added and has both special effects of drag-reducing and heat transfer enhancement. An experiment was carried out to investigate the forced convective flow and heat transfer characteristics of conventional drag reducing fluid (aqueous CTAC solution) and the new drag-reducing nanofluid in a test tube with an inner diameter of 25.6 mm. Results indicated that there were no obvious differences of the drag-reducing characteristics between conventional drag reducing fluid and new drag-reducing nanofluid. However, their heat transfer characteristics were obvious different. The heat transfer characteristics of the new drag-reducing nanofluid significantly depend on the liquid temperature, the nanoparticle concentration and the CTAC concentration. The heat transfer enhancement technology of nanofluid could be applied to solve the problem of heat transfer deterioration for conventional drag-reducing fluids.

Airfoil section characteristics as applied to the prediction of air forces and their distribution on wings

NASA Technical Reports Server (NTRS)

Jacobs, Eastman N; Rhode, R V

1938-01-01

The results of previous reports dealing with airfoil section characteristics and span load distribution data are coordinated into a method for determining the air forces and their distribution on airplane wings. Formulas are given from which the resultant force distribution may be combined to find the wing aerodynamic center and pitching moment. The force distribution may also be resolved to determine the distribution of chord and beam components. The forces are resolved in such a manner that it is unnecessary to take the induced drag into account. An illustration of the method is given for a monoplane and a biplane for the conditions of steady flight and a sharp-edge gust. The force determination is completed by outlining a procedure for finding the distribution of load along the chord of airfoil sections.

CME Dynamics Using STEREO and LASCO Observations: The Relative Importance of Lorentz Forces and Solar Wind Drag

NASA Astrophysics Data System (ADS)

Sachdeva, Nishtha; Subramanian, Prasad; Vourlidas, Angelos; Bothmer, Volker

2017-09-01

We seek to quantify the relative contributions of Lorentz forces and aerodynamic drag on the propagation of solar coronal mass ejections (CMEs). We use Graduated Cylindrical Shell (GCS) model fits to a representative set of 38 CMEs observed with the Solar and Heliospheric Observatory (SOHO) and the Solar and Terrestrial Relations Observatory (STEREO) spacecraft. We find that the Lorentz forces generally peak between 1.65 and 2.45 R⊙ for all CMEs. For fast CMEs, Lorentz forces become negligible in comparison to aerodynamic drag as early as 3.5 - 4 R⊙. For slow CMEs, however, they become negligible only by 12 - 50 R⊙. For these slow events, our results suggest that some of the magnetic flux might be expended in CME expansion or heating. In other words, not all of it contributes to the propagation. Our results are expected to be important in building a physical model for understanding the Sun-Earth dynamics of CMEs.

Using wind setdown and storm surge on Lake Erie to calibrate the air-sea drag coefficient.

PubMed

Drews, Carl

2013-01-01

The air-sea drag coefficient controls the transfer of momentum from wind to water. In modeling storm surge, this coefficient is a crucial parameter for estimating the surge height. This study uses two strong wind events on Lake Erie to calibrate the drag coefficient using the Coupled Ocean Atmosphere Wave Sediment Transport (COAWST) modeling system and the the Regional Ocean Modeling System (ROMS). Simulated waves are generated on the lake with Simulating WAves Nearshore (SWAN). Wind setdown provides the opportunity to eliminate wave setup as a contributing factor, since waves are minimal at the upwind shore. The study finds that model results significantly underestimate wind setdown and storm surge when a typical open-ocean formulation without waves is used for the drag coefficient. The contribution of waves to wind setdown and storm surge is 34.7%. Scattered lake ice also increases the effective drag coefficient by a factor of 1.1.

On the effects of thermal wake from the optical pulsating discharge on the body aerodynamic drag

NASA Astrophysics Data System (ADS)

Kiseleva, T. A.; Golyshev, A. A.; Yakovlev, V. I.; Orishich, A. M.

2018-03-01

The effect of an optical pulsed discharge created by CO2-laser with an average power of 1.8 kW on the aerodynamic drag of a model in a supersonic air flow is experimentally investigated. Experiments were carried out in a supersonic wind tunnel MAU-M (diameter of the nozzle outlet dc = 50 mm) on the modes M = 1,36, Re1 = 1.4-3.8*107 1/m. To ensure a stable optical breakdown, a jet of argon gas was introduced into the focusing region of the laser beam. As a result, a decrease in the aerodynamic drag force was obtained. It is shown, that the increasing of the laser pulses repetition frequency leads to the decreasing in the aerodynamic drag force. The maximum decrease was 15% at a maximum frequency f = 90 kHz.

Swimming gaits, passive drag and buoyancy of diving sperm whales Physeter macrocephalus.

PubMed

Miller, Patrick J O; Johnson, Mark P; Tyack, Peter L; Terray, Eugene A

2004-05-01

Drag and buoyancy are two primary external forces acting on diving marine mammals. The strength of these forces modulates the energetic cost of movement and may influence swimming style (gait). Here we use a high-resolution digital tag to record depth, 3-D orientation, and sounds heard and produced by 23 deep-diving sperm whales in the Ligurian Sea and Gulf of Mexico. Periods of active thrusting versus gliding were identified through analysis of oscillations measured by a 3-axis accelerometer. Accelerations during 382 ascent glides of five whales (which made two or more steep ascents and for which we obtained a measurement of length) were strongly affected by depth and speed at Reynold's numbers of 1.4-2.8x10(7). The accelerations fit a model of drag, air buoyancy and tissue buoyancy forces with an r(2) of 99.1-99.8% for each whale. The model provided estimates (mean +/- S.D.) of the drag coefficient (0.00306+/-0.00015), air carried from the surface (26.4+/-3.9 l kg(-3) mass), and tissue density (1030+/-0.8 kg m(-3)) of these five animals. The model predicts strong positive buoyancy forces in the top 100 m of the water column, decreasing to near neutral buoyancy at 250-850 m. Mean descent speeds (1.45+/-0.19 m s(-1)) were slower than ascent speeds (1.63+/-0.22 m s(-1)), even though sperm whales stroked steadily (glides 5.3+/-6.3%) throughout descents and employed predominantly stroke-and-glide swimming (glides 37.7+/-16.4%) during ascents. Whales glided more during portions of dives when buoyancy aided their movement, and whales that glided more during ascent glided less during descent (and vice versa), supporting the hypothesis that buoyancy influences behavioural swimming decisions. One whale rested at approximately 10 m depth for more than 10 min without fluking, regulating its buoyancy by releasing air bubbles.

Around the Air Force: April 26 > U.S. Air Force > Article Display

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An Aerodynamic Assessment of Micro-Drag Generators (MDGs)

NASA Technical Reports Server (NTRS)

Bauer, Steven X. S.

1998-01-01

Commercial transports as well as fighter aircraft of the future are being designed with very low drag (friction and pressure). Concurrently, commuter airports are being built or envisioned to be built in the centers of metropolitan areas where shorter runways and/or reduced noise footprints on takeoff and landing are required. These requirements and the fact that drag is lower on new vehicles than on older aircraft have resulted in vehicles that require a large amount of braking force (from landing-gear brakes, spoilers, high-lift flaps, thrust reversers, etc.). Micro-drag generators (MDGs) were envisioned to create a uniformly distributed drag force along a vehicle by forcing the flow to separate on the aft-facing surface of a series of deployable devices, thus, generating drag. The devices are intended to work at any speed and for any type of vehicle (aircraft, ground vehicles, sea-faring vehicles). MDGs were applied to a general aviation wing and a representative fuselage shape and tested in two subsonic wind tunnels. The results showed increases in drag of 2 to 6 times that of a "clean" configuration.

The force balance of sea ice in a numerical model of the Arctic Ocean

NASA Astrophysics Data System (ADS)

Steele, Michael; Zhang, Jinlun; Rothrock, Drew; Stern, Harry

1997-09-01

The balance of forces in the sea ice model of Hibler [1979] is examined. The model predicts that internal stress gradients are an important force in much of the Arctic Ocean except in summer, when they are significant only off the northern coasts of Greenland and the Canadian Archipelago. A partition of the internal stress gradient between the pressure gradient and the viscous terms reveals that both are significant, although they operate on very different timescales. The acceleration term is generally negligible, while the sum of Coriolis plus sea surface tilt is small. Thus the seasonal average force balance in fall, winter, and spring is mostly between three terms of roughly equal magnitudes: air drag, water drag, and internal stress gradients. This is also true for the monthly average force balance. However, we find that there is a transition around the weekly timescale and that on a daily basis the force balance at a particular location and time is often between only two terms: either between air drag and water drag or between air drag and internal stress gradients. The model is in agreement with the observations of Thorndike and Colony [1982] in that the correlation between geostrophic wind forcing and the model's ice velocity field is high. This result is discussed in the context of the force balance; we show that the presence of significant internal stress gradients does not preclude high wind-ice correlation. A breakdown of the internal stress gradient into component parts reveals that the shear viscous force is far from negligible, which casts strong doubt on the theoretical validity of the cavitating fluid approximation (in which this component is neglected). Finally, the role of ice pressure is examined by varying the parameter P*. We find a strong sensitivity in terms of the force balance, as well as ice thickness and velocity.

Forces on Elliptic Cylinders in Uniform Air Stream

NASA Technical Reports Server (NTRS)

Zahm, A F; Smith, R H; Louden, F A

1929-01-01

This report presents the results of wind tunnel tests on four elliptic cylinders with various fineness ratios, conducted in the Navy Aerodynamic Laboratory, Washington. The object of the tests was to investigate the characteristics of sections suitable for streamline wire which normally has an elliptic section with a fineness ratio of 4.0; also to learn whether a reduction in fineness ratio would result in improvement; also to determine the pressure distribution on the model of fineness ratio of 4. Four elliptic cylinders with fineness ratios of 2.5, 3.0, 3.5, and 4.0 were made and then tested in the 8 by 8 wind tunnel; first, for cross-wind force, drag, and yawing moment at 30 miles an hour and various angles of yaw; next for drag 0 degree pitch and 0 degree yaw and various wind speeds; then for end effect on the smallest and largest models; and lastly for pressure distribution over the surface of the largest model at 0 degree pitch and 0 degree yaw and various wind speeds. In all tests, the length of the model was transverse to the current. The results are given for standard air density, p = .002378 slug per cubic foot. This account is a slight revised form of report no. 315. A summary of conclusions is given at the end of the text. (author)

Using Wind Setdown and Storm Surge on Lake Erie to Calibrate the Air-Sea Drag Coefficient

PubMed Central

Drews, Carl

2013-01-01

The air-sea drag coefficient controls the transfer of momentum from wind to water. In modeling storm surge, this coefficient is a crucial parameter for estimating the surge height. This study uses two strong wind events on Lake Erie to calibrate the drag coefficient using the Coupled Ocean Atmosphere Wave Sediment Transport (COAWST) modeling system and the the Regional Ocean Modeling System (ROMS). Simulated waves are generated on the lake with Simulating WAves Nearshore (SWAN). Wind setdown provides the opportunity to eliminate wave setup as a contributing factor, since waves are minimal at the upwind shore. The study finds that model results significantly underestimate wind setdown and storm surge when a typical open-ocean formulation without waves is used for the drag coefficient. The contribution of waves to wind setdown and storm surge is 34.7%. Scattered lake ice also increases the effective drag coefficient by a factor of 1.1. PMID:23977309

Air Force Research Laboratory

DTIC Science & Technology

2009-06-08

Air Force Research Laboratory 8 June 2009 Mr. Leo Marple Ai F R h L b t r orce esearc a ora ory Leo.Marple@wpafb.af.mil DISTRIBUTION STATEMENT A...TITLE AND SUBTITLE Air Force Research Laboratory 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER...5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Air Force Research Laboratory ,Wright

The Effective Mass of a Ball in the Air

ERIC Educational Resources Information Center

Messer, J.; Pantaleone, J.

2010-01-01

The air surrounding a projectile affects the projectile's motion in three very different ways: the drag force, the buoyant force, and the added mass. The added mass is an increase in the projectile's inertia from the motion of the air around it. Here we experimentally measure the added mass of a spherical projectile in air. The results agree well…

Air Force Senior Leaders

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Speeches Archive Former AF Top 3 Viewpoints and Speeches Air Force Warrior Games 2017 Events 2018 Air Force Strategic Documents Desert Storm 25th Anniversary Observances DoD Warrior Games Portraits in Courage

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Effects of Deformation on Drag and Lift Forces Acting on a Droplet in a Shear Flow

NASA Astrophysics Data System (ADS)

Suh, Youngho; Lee, Changhoon

2010-11-01

The droplet behavior in a linear shear flow is studied numerically to investigate the effect of deformation on the drag and lift acting on droplet. The droplet shape is calculated by a level set method which is improved by incorporating a sharp-interface modeling technique for accurately enforcing the matching conditions at the liquid- gas interface. By adopting the feedback forces which can maintain the droplet at a fixed position, we determine the acting force on a droplet in shear flow field with efficient handling of deformation. Based on the numerical results, drag and lift forces acting on a droplet are observed to depend strongly on the deformation. Droplet shapes are observed to be spherical, deformed, and oscillating depending on the Reynolds number. Also, the present method is proven to be applicable to a three- dimensional deformation of droplet in the shear flow, which cannot be properly analyzed by the previous studies. Comparisons of the calculated results by the current method with those obtained from body-fitted methods [Dandy and Leal, J. Fluid Mech. 208, 161 (1989)] and empirical models [Feng and Beard, J. Atmos. Sci. 48, 1856 (1991)] show good agreement.

Analysis of data on Air Force personnel collected at Lackland Air Force Base

DOT National Transportation Integrated Search

1969-10-01

In July, 1967, a report was published by the Personnel Research Laboratory, Lackland Air Force Base, entitled "An Attempt to Predict Automobile Accidents Among Air Force Personnnel". Approximately twelve thousand basic airmen and eleven hundred offic...

Air Force officials name SARC of the year > U.S. Air Force > Article

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The Book Speeches Archive Former AF Top 3 Viewpoints and Speeches Air Force Warrior Games 2017 Events 2018 Air Force Strategic Documents Desert Storm 25th Anniversary Observances DoD Warrior Games

Turbulent drag reduction for external flows

NASA Technical Reports Server (NTRS)

Bushnell, D. M.

1985-01-01

A summary of turbulent drag reduction approaches applicable to external flows is given. Because relatively recent and exhaustive reviews exist for laminar flow control and polymer (hydrodynamic) drag reduction, the focus here is upon the emerging areas of nonplanar geometry and large-eddy alteration. Turbulent control techniques for air generally result in modest (but technologically significant) drag reductions (order of 20 percent or less), whereas hydrodynamic approaches can yield drag reductions the order of 70 percent. Suggestions are included for alternative concepts and optimization of existing approaches.

33 CFR 334.590 - Atlantic Ocean off Cape Canaveral, Fla.; Air Force missile testing area, Patrick Air Force Base...

Code of Federal Regulations, 2011 CFR

2011-07-01

..., Fla.; Air Force missile testing area, Patrick Air Force Base, Fla. 334.590 Section 334.590 Navigation... RESTRICTED AREA REGULATIONS § 334.590 Atlantic Ocean off Cape Canaveral, Fla.; Air Force missile testing area... during firing periods to be specified by the Commander, Air Force Missile Test Center, Patrick Air Force...

33 CFR 334.590 - Atlantic Ocean off Cape Canaveral, Fla.; Air Force missile testing area, Patrick Air Force Base...

Code of Federal Regulations, 2013 CFR

2013-07-01

..., Fla.; Air Force missile testing area, Patrick Air Force Base, Fla. 334.590 Section 334.590 Navigation... RESTRICTED AREA REGULATIONS § 334.590 Atlantic Ocean off Cape Canaveral, Fla.; Air Force missile testing area... during firing periods to be specified by the Commander, Air Force Missile Test Center, Patrick Air Force...

33 CFR 334.590 - Atlantic Ocean off Cape Canaveral, Fla.; Air Force missile testing area, Patrick Air Force Base...

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2012-07-01

..., Fla.; Air Force missile testing area, Patrick Air Force Base, Fla. 334.590 Section 334.590 Navigation... RESTRICTED AREA REGULATIONS § 334.590 Atlantic Ocean off Cape Canaveral, Fla.; Air Force missile testing area... during firing periods to be specified by the Commander, Air Force Missile Test Center, Patrick Air Force...

33 CFR 334.590 - Atlantic Ocean off Cape Canaveral, Fla.; Air Force missile testing area, Patrick Air Force Base...

Code of Federal Regulations, 2014 CFR

2014-07-01

..., Fla.; Air Force missile testing area, Patrick Air Force Base, Fla. 334.590 Section 334.590 Navigation... RESTRICTED AREA REGULATIONS § 334.590 Atlantic Ocean off Cape Canaveral, Fla.; Air Force missile testing area... during firing periods to be specified by the Commander, Air Force Missile Test Center, Patrick Air Force...

Turbulent drag reduction for external flows

NASA Technical Reports Server (NTRS)

Bushnell, D. M.

1983-01-01

Paper presents a review and summary of turbulent drag reduction approaches applicable to external flows. Because relatively recent and exhaustive reviews exist for laminar flow control and polymer (hydrodynamic) drag reduction, the paper focuses upon the emerging areas of nonplanar geometry and large eddy alteration. Turbulent control techniques for air generally result in modest (but technologically significant) drag reductions (order of 20 percent or less) whereas hydrodynamic approaches can yield drag reductions the order of 70 percent. Paper also includes suggestions for alternative concepts and optimization of existing approaches.

Finding of No Significant Impact: First Air Force Air Operations Center, First Air Force Headquarters/Air Force Forces Center, and Highway 98 Overpass at Tyndall Air Force Base, Florida

DTIC Science & Technology

2004-11-10

found at the following web address: <http://dep.state.fl.us/air/forms/asbestos.htm#asbestos>. The Air Force is advised to contact Sandra Veazey at...advised to contact Sandra Veazey at (850) 595·8300 for additional information on asbestos issues. http://tlhora6.dep.state.fl.us/clearinghouse/agency

Drag reduction of a hairy disk

NASA Astrophysics Data System (ADS)

Niu, Jun; Hu, David L.

2011-10-01

We investigate experimentally the hydrodynamics of a hairy disk immersed in a two-dimensional flowing soap film. Drag force is measured as a function of hair length, density, and coating area. An optimum combination of these parameters yields a drag reduction of 17%, which confirms previous numerical predictions (15%). Flow visualization indicates the primary mechanism for drag reduction is the bending, adhesion, and reinforcement of hairs trailing the disk, which reduces wake width and traps "dead water." Thus, the use of hairy coatings can substantially reduce an object's drag while negligibly increasing its weight.

Relativistic Gas Drag on Dust Grains and Implications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoang, Thiem, E-mail: thiemhoang@kasi.re.kr; Korea University of Science and Technology, Daejeon, 34113

We study the drag force on grains moving at relativistic velocities through interstellar gas and explore its application. First, we derive a new analytical formula of the drag force at high energies and find that it is significantly reduced compared to the classical model. Second, we apply the obtained drag force to calculate the terminal velocities of interstellar grains by strong radiation sources such as supernovae and active galactic nuclei (AGNs). We find that grains can be accelerated to relativistic velocities by very luminous AGNs. We then quantify the deceleration of relativistic spacecraft proposed by the Breakthrough Starshot initiative duemore » to gas drag on a relativistic lightsail. We find that the spacecraft’s decrease in speed is negligible because of the suppression of gas drag at relativistic velocities, suggesting that the lightsail may be open for communication during its journey to α Centauri without causing a considerable delay. Finally, we show that the damage to relativistic thin lightsails by interstellar dust is a minor effect.« less

Unsteady motion, finite Reynolds numbers, and wall effect on Vorticella convallaria contribute contraction force greater than the stokes drag.

PubMed

Ryu, Sangjin; Matsudaira, Paul

2010-06-02

Contraction of Vorticella convallaria, a sessile ciliated protozoan, is completed within a few milliseconds and results in a retraction of its cell body toward the substratum by coiling its stalk. Previous studies have modeled the cell body as a sphere and assumed a drag force that satisfies Stokes' law. However, the contraction-induced flow of the medium is transient and bounded by the substrate, and the maximum Reynolds number is larger than unity. Thus, calculations of contractile force from the drag force are incomplete. In this study, we analyzed fluid flow during contraction by the particle tracking velocimetry and computational fluid dynamics simulations to estimate the contractile force. Particle paths show that the induced flow is limited by the substrate. Simulation-based force estimates suggest that the combined effect of the flow unsteadiness, the finite Reynolds number, and the substrate comprises 35% of the total force. The work done in the early stage of contraction and the maximum power output are similar regardless of the medium viscosity. These results suggest that, during the initial development of force, V. convallaria uses a common mechanism for performing mechanical work irrespective of viscous loading conditions. Copyright (c) 2010 Biophysical Society. Published by Elsevier Inc. All rights reserved.

On the Effect of Rigid Swept Surface Waves on Turbulent Drag

NASA Technical Reports Server (NTRS)

Denison, M.; Wilkinson, S. P.; Balakumar, P.

2015-01-01

Passive turbulent drag reduction techniques are of interest as a cost effective means to improve air vehicle fuel consumption. In the past, rigid surface waves slanted at an angle from the streamwise direction were deemed ineffective to reduce skin friction drag due to the pressure drag that they generate. A recent analysis seeking similarities to the spanwise shear stress generated by spatial Stokes layers suggested that there may be a range of wavelength, amplitude, and orientation in which the wavy surface would reduce turbulent drag. The present work explores, by experiments and Direct Numerical Simulations (DNS), the effect of swept wavy surfaces on skin friction and pressure drag. Plates with shallow and deep wave patterns were rapid-prototyped and tested using a drag balance in the 7x11 inch Low-Speed Wind Tunnel at the NASA LaRC Research Center. The measured drag o set between the wavy plates and the reference at plate is found to be within the experimental repeatability limit. Oil vapor flow measurements indicate a mean spanwise flow over the deep waves. The turbulent flow in channels with at walls, swept wavy walls and spatial Stokes spanwise velocity forcing was simulated at a friction Reynolds number of two hundred. The time-averaged and dynamic turbulent flow characteristics of the three channel types are compared. The drag obtained for the channel with shallow waves is slightly larger than for the at channel, within the range of the experiments. In the case of the large waves, the simulation over predicts the drag. The shortcomings of the Stokes layer analogy model for the estimation of the spanwise shear stress and drag are discussed.

Drag De-Orbit Device (D3): A Retractable Device for CubeSat Attitude and Orbit Control using Aerodynamic Forces

NASA Technical Reports Server (NTRS)

Guglielmo, David; Omar, Sanny R.; Bevilacqua, Riccardo

2017-01-01

The increasing number of CubeSats being launched has raised concerns about orbital debris since most of these satellites have no means of active orbit control. Some technologies exist to increase the surface area of a CubeSat and expedite de-orbit due to aerodynamic drag in low Earth orbit, but most of these devices cannot be retracted and hence cannot be used for orbital maneuvering. This paper discusses the De-Orbit Drag Device (D3) module that is capable of de-orbiting a 12U, 15kg CubeSat from a 700 km circular orbit in under 25 years and can be deployed and retracted to modulate the aerodynamic drag force experienced by the satellite. This facilitates orbital maneuvering using aerodynamic drag and the active targeting of a de-orbit location. In addition, the geometry of this drag device provides 3-axis attitude stabilization of the host CubeSat using aerodynamic and gravity gradient torques which is useful for many missions and provides a predictable aerodynamic profile for use in orbital maneuvering algorithms.

Air Force Medical Service > Resources > Suicide Prevention

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Air Force Medical Service Air Force Medical Service Join the Air Force Home Your Healthcare Healthy Videos MHS Genesis AFMS Priorities Trusted Care Vision Air Force Medical Home Full Spectrum Medical ) Air Force EFMP Who is an EFM? Who must enroll? EFMP-Medical EFMP-M Objectives Family Criteria EFMP-M

Possibilities for drag reduction by boundary layer control

NASA Technical Reports Server (NTRS)

Naiman, I.

1946-01-01

The mechanics of laminar boundary layer transition are reviewed. Drag possibilities for boundary layer control are analyzed using assumed conditions of transition Reynolds number, inlet loss, number of slots, blower efficiency, and duct losses. Although the results of such analysis are highly favorable, those obtained by experimental investigations yield conflicting results, showing only small gains, and sometimes losses. Reduction of this data indicates that there is a lower limit to the quantity of air which must be removed at the slot in order to stabilize the laminar flow. The removal of insufficient air permits transition to occur while the removal of excessive amounts of air results in high power costs, with a net drag increases. With the estimated value of flow coefficient and duct losses equal to half the dynamic pressure, drag reductions of 50% may be obtained; with twice this flow coefficient, the drag saving is reduced to 25%.

Aerodynamic drag reduction tests on a full-scale tractor-trailer combination with several add-on devices

NASA Technical Reports Server (NTRS)

Montoya, L. C.; Steers, L. L.

1974-01-01

Aerodynamic drag tests were performed on a conventional cab-over-engine tractor with a 45-foot trailer and five commercially available or potentially available add-on devices using the coast-down method. The tests ranged in velocity from approximately 30 miles per hour to 65 miles per hour and included some flow visualization. A smooth, level runway at Edwards Air Force Base was used for the tests, and deceleration measurements were taken with both accelerometers and stopwatches. An evaluation of the drag reduction results obtained with each of the five add-on devices is presented.

Drag king magic: performing/becoming the other.

PubMed

Rosenfeld, Kathryn

2002-01-01

This chapter seeks to theorize drag king practice through the lenses of alterity, liminality, and performance theory, while attempting to complicate and reinvigorate discussions of identity raised by drag. I examine the ways in which drag king performance plumbs the concept of "the Other," and forces confrontation with a complex field of desire. Contemporary "queergirl" existence negotiates a range of desirable and desiring Others, from the polarities (i.e., butch-femme) unique to queer structures of desire, to the desire of those on the cultural margins for the power of those at the center, and vice versa. I employ anthropological theories of performance, mimesis, and liminality to establish a framework through which drag kings may be viewed as crucibles of this desire and agents of this power exchange. By performing maleness, drag kings expand and redraw the definitional boundaries of the male, interfere with the cultural power of mainstream maleness, and simultaneously transfer some of this power to themselves as queer women. At the same time, drag king existence forces a renegotiation of queergirl desire to encompass a range of masculinities. By performing/becoming the Other, drag kings engage in a practice of magic which transforms both margin and center.

Group 13 1990 ASCAN Sherlock during Vance AFB parachute drag training

NASA Image and Video Library

1990-08-14

S90-45883 (29-31 July 1990) --- Nancy J. Sherlock, one of 23 astronaut candidates who began a year's training and evaluation in July, participates in one of many sessions at a survival training course at Vance Air Force Base. Sherlock is about to take part in parachute drag training. The overall course is designed to familiarize the trainees with procedures to follow in the event of an emergency ejection from a jet aircraft.

Experimental study of microbubble drag reduction on an axisymmetric body

NASA Astrophysics Data System (ADS)

Song, Wuchao; Wang, Cong; Wei, Yingjie; Zhang, Xiaoshi; Wang, Wei

2018-01-01

Microbubble drag reduction on the axisymmetric body is experimentally investigated in the turbulent water tunnel. Microbubbles are created by injecting compressed air through the porous medium with various average pore sizes. The morphology of microbubble flow and the size distribution of microbubble are observed by the high-speed visualization system. Drag measurements are obtained by the balance which is presented as the function of void ratio. The results show that when the air injection flow rate is high, uniformly dispersed microbubble flow is coalesced into an air layer with the larger increment rate of drag reduction ratio. The diameter distributions of microbubble under various conditions are submitted to normal distribution. Microbubble drag reduction can be divided into three distinguishable regions in which the drag reduction ratio experiences increase stage, rapid increase stage and stability stage, respectively, corresponding to the various morphologies of microbubble flow. Moreover, drag reduction ratio increases with the decreasing pore sizes of porous medium at the identical void ratio in the area of low speeds, while the effect of pore sizes on drag reduction is reduced gradually until it disappears with the increasing free stream speeds, which indicates that smaller microbubbles have better efficiency in drag reduction. This research results help to improve the understanding of microbubble drag reduction and provides helpful references for practical applications.

Creating drag and lift curves from soccer trajectories

NASA Astrophysics Data System (ADS)

Goff, John Eric; Kelley, John; Hobson, Chad M.; Seo, Kazuya; Asai, Takeshi; Choppin, S. B.

2017-07-01

Trajectory analysis is an alternative to using wind tunnels to measure a soccer ball’s aerodynamic properties. It has advantages over wind tunnel testing such as being more representative of game play. However, previous work has not presented a method that produces complete, speed-dependent drag and lift coefficients. Four high-speed cameras in stereo-calibrated pairs were used to measure the spatial co-ordinates for 29 separate soccer trajectories. Those trajectories span a range of launch speeds from 9.3 to 29.9 m s-1. That range encompasses low-speed laminar flow of air over a soccer ball, through the drag crises where air flow is both laminar and turbulent, and up to high-speed turbulent air flow. Results from trajectory analysis were combined to give speed-dependent drag and lift coefficient curves for the entire range of speeds found in the 29 trajectories. The average root mean square error between the measured and modelled trajectory was 0.028 m horizontally and 0.034 m vertically. The drag and lift crises can be observed in the plots of drag and lift coefficients respectively.

32 CFR 855.22 - Air Force procedures.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 32 National Defense 6 2013-07-01 2013-07-01 false Air Force procedures. 855.22 Section 855.22 National Defense Department of Defense (Continued) DEPARTMENT OF THE AIR FORCE AIRCRAFT CIVIL AIRCRAFT USE OF UNITED STATES AIR FORCE AIRFIELDS Agreements for Civil Aircraft Use of Air Force Airfields § 855...

32 CFR 855.22 - Air Force procedures.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 32 National Defense 6 2010-07-01 2010-07-01 false Air Force procedures. 855.22 Section 855.22 National Defense Department of Defense (Continued) DEPARTMENT OF THE AIR FORCE AIRCRAFT CIVIL AIRCRAFT USE OF UNITED STATES AIR FORCE AIRFIELDS Agreements for Civil Aircraft Use of Air Force Airfields § 855...

32 CFR 855.22 - Air Force procedures.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 32 National Defense 6 2011-07-01 2011-07-01 false Air Force procedures. 855.22 Section 855.22 National Defense Department of Defense (Continued) DEPARTMENT OF THE AIR FORCE AIRCRAFT CIVIL AIRCRAFT USE OF UNITED STATES AIR FORCE AIRFIELDS Agreements for Civil Aircraft Use of Air Force Airfields § 855...

U.S. Air Force > SAPR

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for treatment in the military health system, and Air Force civilian (appropriated and non-appropriated (or equivalent) or installation vice wing commander, executing the Air Force's Sexual Assault

Electro-hydrodynamic force field and flow patterns generated by a DC corona discharge in the air

NASA Astrophysics Data System (ADS)

Monrolin, Nicolas; Plouraboue, Franck; Praud, Olivier

2016-11-01

Ionic wind refers to the electro-convection of ionised air between high voltage electrodes. Microscopic ion-neutral collisions are responsible for momentum transfer from accelerated ions, subjected to the electric field, to the neutral gas molecules resulting in a macroscopic airflow acceleration. In the past decades it has been investigated for various purposes from food drying through aerodynamic flow control and eventually laptop cooling. One consequence of air acceleration between the electrodes is thrust generation, often referred to as the Biefeld-Brown effect or electro-hydrodynamic thrust. In this experimental study, the ionic wind velocity field is measured with the PIV method. From computing the acceleration of the air we work out the electrostatic force field for various electrodes configurations. This enables an original direct evaluation of the force distribution as well as the influence of electrodes shape and position. Thrust computation based on the flow acceleration are compared with digital scale measurements. Complex flow features are highlighted such as vortex shedding, indicating that aerodynamic effects may play a significant role. Furthermore, the aerodynamic drag force exerted on the electrodes is quantified by choosing an appropriate control volume. Authors thank Region Midi-Pyrenee and CNES Launcher Directorate for financial support.

Computation of H2/air reacting flowfields in drag-reduction external combustion

NASA Technical Reports Server (NTRS)

Lai, H. T.

1992-01-01

Numerical simulation and analysis of the solution are presented for a laminar reacting flowfield of air and hydrogen in the case of external combustion employed to reduce base drag in hypersonic vehicles operating at transonic speeds. The flowfield consists of a transonic air stream at a Mach number of 1.26 and a sonic transverse hydrogen injection along a row of 26 orifices. Self-sustained combustion is computed over an expansion ramp downstream of the injection and a flameholder, using the recently developed RPLUS code. Measured data is available only for surface pressure distributions and is used for validation of the code in practical 3D reacting flowfields. Pressure comparison shows generally good agreements, and the main effects of combustion are also qualitatively consistent with experiment.

Drag reduction through self-texturing compliant bionic materials

PubMed Central

Liu, Eryong; Li, Longyang; Wang, Gang; Zeng, Zhixiang; Zhao, Wenjie; Xue, Qunji

2017-01-01

Compliant fish skin is effectively in reducing drag, thus the design and application of compliant bionic materials may be a good choice for drag reduction. Here we consider the drag reduction of compliant bionic materials. First, ZnO and PDMS mesh modified with n-octadecane were prepared, the drag reduction of self-texturing compliant n-octadecane were studied. The results show that the mesh modified by ZnO and PDMS possess excellent lipophilic and hydrophobic, thus n-octadecane at solid, semisolid and liquid state all have good adhesion with modified mesh. The states of n-octadecane changed with temperature, thus, the surface contact angle and adhesive force all varies obviously at different state. The contact angle decreases with temperature, the adhesive force shows a lower value at semisolid state. Furthermore, the drag testing results show that the compliant n-octadecane film is more effectively in drag reduction than superhydrophobic ZnO/PDMS film, indicating that the drag reduction mechanism of n-octadecane is significantly different with superhydrophobic film. Further research shows that the water flow leads to self-texturing of semisolid state n-octadecane, which is similar with compliant fish skin. Therefore, the compliant bionic materials of semisolid state n-octadecane with regular bulge plays a major role in the drag reduction. PMID:28053309

Drag reduction through self-texturing compliant bionic materials.

PubMed

Liu, Eryong; Li, Longyang; Wang, Gang; Zeng, Zhixiang; Zhao, Wenjie; Xue, Qunji

2017-01-05

Compliant fish skin is effectively in reducing drag, thus the design and application of compliant bionic materials may be a good choice for drag reduction. Here we consider the drag reduction of compliant bionic materials. First, ZnO and PDMS mesh modified with n-octadecane were prepared, the drag reduction of self-texturing compliant n-octadecane were studied. The results show that the mesh modified by ZnO and PDMS possess excellent lipophilic and hydrophobic, thus n-octadecane at solid, semisolid and liquid state all have good adhesion with modified mesh. The states of n-octadecane changed with temperature, thus, the surface contact angle and adhesive force all varies obviously at different state. The contact angle decreases with temperature, the adhesive force shows a lower value at semisolid state. Furthermore, the drag testing results show that the compliant n-octadecane film is more effectively in drag reduction than superhydrophobic ZnO/PDMS film, indicating that the drag reduction mechanism of n-octadecane is significantly different with superhydrophobic film. Further research shows that the water flow leads to self-texturing of semisolid state n-octadecane, which is similar with compliant fish skin. Therefore, the compliant bionic materials of semisolid state n-octadecane with regular bulge plays a major role in the drag reduction.

Drag reduction through self-texturing compliant bionic materials

NASA Astrophysics Data System (ADS)

Liu, Eryong; Li, Longyang; Wang, Gang; Zeng, Zhixiang; Zhao, Wenjie; Xue, Qunji

2017-01-01

Compliant fish skin is effectively in reducing drag, thus the design and application of compliant bionic materials may be a good choice for drag reduction. Here we consider the drag reduction of compliant bionic materials. First, ZnO and PDMS mesh modified with n-octadecane were prepared, the drag reduction of self-texturing compliant n-octadecane were studied. The results show that the mesh modified by ZnO and PDMS possess excellent lipophilic and hydrophobic, thus n-octadecane at solid, semisolid and liquid state all have good adhesion with modified mesh. The states of n-octadecane changed with temperature, thus, the surface contact angle and adhesive force all varies obviously at different state. The contact angle decreases with temperature, the adhesive force shows a lower value at semisolid state. Furthermore, the drag testing results show that the compliant n-octadecane film is more effectively in drag reduction than superhydrophobic ZnO/PDMS film, indicating that the drag reduction mechanism of n-octadecane is significantly different with superhydrophobic film. Further research shows that the water flow leads to self-texturing of semisolid state n-octadecane, which is similar with compliant fish skin. Therefore, the compliant bionic materials of semisolid state n-octadecane with regular bulge plays a major role in the drag reduction.

MP-Pic simulation of CFB riser with EMMS-based drag model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, F.; Song, F.; Benyahia, S.

2012-01-01

MP-PIC (multi-phase particle in cell) method combined with the EMMS (energy minimization multi- scale) drag force model was implemented with the open source program MFIX to simulate the gas–solid flows in CFB (circulatingfluidizedbed) risers. Calculated solid flux by the EMMS drag agrees well with the experimental value; while the traditional homogeneous drag over-predicts this value. EMMS drag force model can also predict the macro-and meso-scale structures. Quantitative comparison of the results by the EMMS drag force model and the experimental measurements show high accuracy of the model. The effects of the number of particles per parcel and wall conditions onmore » the simulation results have also been investigated in the paper. This work proved that MP-PIC combined with the EMMS drag model can successfully simulate the fluidized flows in CFB risers and it serves as a candidate to realize real-time simulation of industrial processes in the future.« less

A lone desert Joshua tree greeted the arrival of Space Shuttle Endeavour at Edwards Air Force Base, California, on May 1, 2001

NASA Image and Video Library

2001-05-01

A lone desert Joshua tree greeted the arrival of Space Shuttle Endeavour at Edwards Air Force Base, California, May 1, 2001. A large drag chute helped slow Endeavour on the runway. After mounting the shuttle on a converted 747 airliner at NASA's Dryden Flight Research Center, Endeavour will be carried back to the Kennedy Space Center for its next mission. Weather in Florida necessitated landing in California.

The ‘W’ Prawn-Trawl with Emphasised Drag-Force Transfer to Its Centre Line to Reduce Overall System Drag

PubMed Central

Balash, Cheslav; Sterling, David; Binns, Jonathan; Thomas, Giles; Bose, Neil

2015-01-01

For prawn trawling systems, drag reduction is a high priority as the trawling process is energy intensive. Large benefits have occurred through the use of multiple-net rigs and thin twine in the netting. An additional positive effect of these successful twine-area reduction strategies is the reduced amount of otter board area required to spread the trawl systems, which leads to further drag reduction. The present work investigated the potential of redirecting the drag-strain within a prawn trawl away from the wings and the otter boards to the centre line of the trawl, where top and bottom tongues have been installed, with an aim to minimise the loading/size of the otter boards required to spread the trawl. In the system containing the new ‘W’ trawl, the drag redirected to the centre-line tongues is transferred forward through a connected sled and towing wires to the trawler. To establish the extent of drag redirection to the centre-line tongues and the relative drag benefits of the new trawl system, conventional and ‘W’ trawls of 3.65 m headline length were tested firstly over a range of spread ratios in the flume tank, and subsequently at optimum spread ratio in the field. The developed ‘W’ trawl effectively directed 64% of netting-drag off the wings and onto the centre tongues, which resulted in drag savings in the field of ∼20% for the associated ‘W’ trawl/otter-board/sled system compared to the traditional trawl/otter-board arrangement in a single trawl or twin rig configuration. Furthermore, based on previously published data, the new trawl when used in a twin rig system is expected to provide approximately 12% drag reduction compared to quad rig. The twin ‘W’ trawl system also has benefits over quad rig in that a reduced number of cod-end/By-catch Reduction Device units need to be installed and attended each tow. PMID:25751251

33 CFR 334.590 - Atlantic Ocean off Cape Canaveral, Fla.; Air Force missile testing area, Patrick Air Force Base...

Code of Federal Regulations, 2010 CFR

2010-07-01

..., Fla.; Air Force missile testing area, Patrick Air Force Base, Fla. 334.590 Section 334.590 Navigation... RESTRICTED AREA REGULATIONS § 334.590 Atlantic Ocean off Cape Canaveral, Fla.; Air Force missile testing area, Patrick Air Force Base, Fla. (a) The danger zone. An area in the Atlantic Ocean immediately offshore from...

The Effect of Volumetric Porosity on Roughness Element Drag

NASA Astrophysics Data System (ADS)

Gillies, John; Nickling, William; Nikolich, George; Etyemezian, Vicken

2016-04-01

Much attention has been given to understanding how the porosity of two dimensional structures affects the drag force exerted by boundary-layer flow on these flow obstructions. Porous structures such as wind breaks and fences are typically used to control the sedimentation of sand and snow particles or create micro-habitats in their lee. Vegetation in drylands also exerts control on sediment transport by wind due to aerodynamic effects and interaction with particles in transport. Recent research has also demonstrated that large spatial arrays of solid three dimensional roughness elements can be used to reduce sand transport to specified targets for control of wind erosion through the effect of drag partitioning and interaction of the moving sand with the large (>0.3 m high) roughness elements, but porous elements may improve the effectiveness of this approach. A thorough understanding of the role porosity plays in affecting the drag force on three-dimensional forms is lacking. To provide basic understanding of the relationship between the porosity of roughness elements and the force of drag exerted on them by fluid flow, we undertook a wind tunnel study that systematically altered the porosity of roughness elements of defined geometry (cubes, rectangular cylinders, and round cylinders) and measured the associated change in the drag force on the elements under similar Reynolds number conditions. The elements tested were of four basic forms: 1) same sized cubes with tubes of known diameter milled through them creating three volumetric porosity values and increasing connectivity between the tubes, 2) cubes and rectangular cylinders constructed of brass screen that nested within each other, and 3) round cylinders constructed of brass screen that nested within each other. The two-dimensional porosity, defined as the ratio of total surface area of the empty space to the solid surface area of the side of the element presented to the fluid flow was conserved at 0.519 for

Drag and Lift Forces Between a Rotating Conductive Sphere and a Cylindrical Magnet

NASA Technical Reports Server (NTRS)

Nurge, Mark A.; Youngquist, Robert C.

2017-01-01

Modeling the interaction between a non-uniform magnetic field and a rotating conductive object allows study of the drag force which is used in applications such as eddy current braking and linear induction motors as well as the transition to a repulsive force that is the basis for magnetic levitation systems. Here, we study the interaction between a non-uniform field generated by a cylindrical magnet and a rotating conductive sphere. Each eddy current in the sphere generates a magnetic field which in turn generates another eddy current, eventually feeding back on itself. A two step mathematics process is developed to find a closed form solution in terms of only two eddy currents. However, the complete solution requires decomposition of the magnetic field into a summation of spherical harmonics, making it more suitable for a graduate level electromagnetism lecture or lab. Finally, the forces associated with these currents are calculated and then verified experimentally.

Drag and lift forces between a rotating conductive sphere and a cylindrical magnet

NASA Astrophysics Data System (ADS)

Nurge, Mark A.; Youngquist, Robert C.; Starr, Stanley O.

2018-06-01

Modeling the interaction between a non-uniform magnetic field and a rotating conductive object provides insight into the drag force, which is used in applications such as eddy current braking and linear induction motors, as well as the transition to a repulsive force, which is the basis for magnetic levitation systems. Here, we study the interaction between a non-uniform field generated by a cylindrical magnet and a rotating conductive sphere. Each eddy current in the sphere generates a magnetic field which in turn generates another eddy current, eventually feeding back on itself. A two-step mathematical process is developed to find a closed-form solution in terms of only three eddy currents. However, the complete solution requires decomposition of the magnetic field into a summation of spherical harmonics, making it more suitable for a graduate-level electromagnetism lecture or lab. Finally, the forces associated with these currents are calculated and then verified experimentally.

When superfluids are a drag

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roberts, David C

2008-01-01

The article considers the dramatic phenomenon of seemingly frictionless flow of slow-moving superfluids. Specifically the question of whether an object in a superfluid flow experiences any drag force is addressed. A brief account is given of the history of this problem and it is argued that recent advances in ultracold atomic physics can shed much new light on this problem. The article presents the commonly held notion that sufficiently slow-moving superfluids can flow without drag and also discusses research suggesting that scattering quantum fluctuations might cause drag in a superfluid moving at any speed.

Inspector General, DoD, Oversight of the Air Force Audit Agency Audit of the FY 1996 Air Force Consolidated Financial Statements.

DTIC Science & Technology

1997-04-10

financial statements . We delegated the audit of the FY 1996 Air Force consolidated financial statements to the Air Force Audit Agency on May 17, 1996...This report provides our endorsement of the Air Force Audit Agency disclaimer of opinion on the Air Force consolidated financial statements for FY...1996, along with the Air Force Audit Agency Report of Audit, ’Opinion on Fiscal Year 1996 Air Force Consolidated Financial Statements .’

Reduction of turbulent skin-friction drag by oscillating discs

NASA Astrophysics Data System (ADS)

Wise, Daniel; Ricco, Pierre

2013-11-01

A new drag-reduction method, based on the active technique proposed by Ricco & Hahn (2013), i.e. steadily rotating flush-mounted discs, is studied by DNS. The effect of sinusoidally oscillating discs on the turbulent channel-flow drag is investigated at Reτ = 180 , based on the friction velocity of the stationary-wall case and the half channel height. A parametric investigation on the disc diameter, tip velocity and oscillation period yielded a maximum drag reduction of 18.5%. Regions of net power saved, calculated by considering the power spent to enforce the disc motion against the viscous resistance of the fluid, are found to reach up to 6.5% for low disc tip velocities. Significantly, the characteristic time-scale for the oscillating disc forcing is double that for the steadily rotating discs, representing a further step towards industrial implementation. The oscillating disc forcing, similar to the steadily rotating disc forcing, creates streamwise-elongated structures between the discs. These structures - largely unaffected by the periodic wall forcing and persisting throughout the entire period of the oscillation - are the main contributor to the additional Reynolds stresses term created by the disc forcing, and are important for the drag reduction mechanism.

Secretary of the Air Force

Science.gov Websites

Speeches Archive Former AF Top 3 Viewpoints and Speeches Air Force Warrior Games 2017 Events 2018 Air Force Strategic Documents Desert Storm 25th Anniversary Observances DoD Warrior Games Portraits in Courage

Air Force Research Laboratory Preparation for Year 2000.

DTIC Science & Technology

1998-10-05

Air Force Research Laboratory , Phillips Research Site , Kirkland Air Force Base, New...Pentagon, Washington, D.C. 20301-1900. The identity of each writer and caller is fully protected. Acronym AFRL Air Force Research Laboratory INSPECTOR...completion of the implementation phase was May 31, 1999. Air Force Research Laboratory . The Air Force Research

Environmental Assessment, Balloon Launch and Landing Operations, Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, New Mexico

DTIC Science & Technology

2012-06-01

Force Research Laboratory , Space Vehicles Directorate ( AFRL /RV) located at Kirtland Air Force Base is preparing an Environmental Assessment (EA) for...United States Air Force Research Laboratory , Space Vehicles Directorate ( AFRL /RV) located at Kirtland Air Force Base is preparing an Environmental...United States Air Force Research Laboratory , Space Vehicles Directorate ( AFRL

List of EPA Certified Forced-Air Furnaces

EPA Pesticide Factsheets

The EPA-Certified Forced-Air Furnace list contains EPA-certified forced-air furnaces that meet the 2015 NSPS for New Residential Wood Heaters, New Residential Hydronic Heaters and Forced-Air Furnaces.

The Air Force Nurse Intern Program.

PubMed

Smith, R H

1991-08-01

The Air Force Nurse Intern Program is a 5-month-long introduction to Air Force nursing for BSN-prepared graduate nurses. The program is designed to facilitate the transition from civilian nursing student to practicing Air Force Nurse Corps Officer. After attending Military Indoctrination for Medical Service Officers, newly commissioned nurses attend the program at one of 10 Air Force medical centers before going to their permanent duty stations. Preceptors guide and instruct the interns at each of four clinical rotation sites. The author, a former nurse intern, describes some of the many opportunities available to nurse interns.

Inspector General, DOD, Oversight of the Air Force Audit Agency Audit of the FY 1995 Air Force Consolidated Financial Statements.

DTIC Science & Technology

1996-04-18

financial statements . We delegated the audit of the FY 1995 Air Force consolidated financial statements to the Air Force Audit Agency. On March 1...1996, the Air Force Audit Agency issued its "Report of Audit: Opinion on Fiscal Year 1995 Air Force Consolidated Financial Statements " (Project 94053001...disclaimer of opinion. The audit objective was to determine the accuracy and completeness of the audit of the FY 1995 Air Force consolidated financial statements conducted

Translational viscous drags of an ellipsoid straddling an interface between two fluids.

PubMed

Boniello, Giuseppe; Stocco, Antonio; Gross, Michel; In, Martin; Blanc, Christophe; Nobili, Maurizio

2016-07-01

We study the dynamics of individual polystyrene ellipsoids of different aspect ratios trapped at the air-water interface. Using particle tracking and in situ vertical scanning interferometry techniques we are able to measure translational drags and the protrusion in air of the ellipsoids. We report that translational drags on the ellipsoid are unexpectedly enhanced: despite the fact that a noticeable part of the ellipsoid is in air, drags are found larger than the bulk one in water.

Remodeling Air Force Cyber Command and Control

DTIC Science & Technology

2017-10-10

AIR FORCE CYBERWORX REPORT: REMODELING AIR FORCE CYBER COMMAND & CONTROL COURSE DESIGN PROJECT CONDUCTED 5 Jan – 5 May 17 Produced...For the Air Force Cyber Command and Control (C2) Design Project, CyberWorx brought together 25 cadets from the United States Air Force Academy...warfighting based upon the findings of the design teams. Participants The design course was attended by a diverse group of civilians from industry

Relaxation drag history of shock accelerated microparticles

DOE PAGES

Bordoloi, Ankur D.; Martinez, Adam A.; Prestridge, Katherine

2017-06-21

Experimental measurements of the displacements of shock accelerated microparticles from shortly after shock interaction to the particle relaxation time show time-dependent drag coefficients (more » $$C_{D}$$) that are much higher than those predicted by quasi-steady and unsteady drag models. Nylon particles with mean diameter of $$4~\\unicode[STIX]{x03BC}\\text{m}$$, accelerated by one-dimensional normal shocks (Mach number$$M_{s}=1.2$$, 1.3 and 1.4), have measured$$C_{D}$$values that follow a power-law behaviour. The drag is a function of the time-dependent Knudsen number,$$Kn^{\\ast }=M_{s}/Re_{p}$$, where the particle Reynolds number ($$Re_{p}$$) is calculated using the time-dependent slip velocity. Also, some portion of the drag can be attributed to quasi-steady forces, but the total drag cannot be predicted by current unsteady force models that are based on the Basset–Boussinesq–Oseen equation and pressure drag. The largest contribution to the total drag is the unsteady component ($$C_{D,us}$$) until the particle attains$$Kn^{\\ast }\\approx 0.5{-}1.0$$, then the unsteady contribution decays. The quasi-steady component ($$C_{D,qs}$$) increases almost linearly with$$Kn^{\\ast }$$, intersects the$$C_{D,us}$$at$$Kn^{\\ast }\\approx 2$$and becomes the primary contributor to the drag towards the end of the relaxation zone as$$Re_{p}\\rightarrow 0$$. Finally, there are currently no analytical models that are able to predict the nonlinear behaviour of the shock accelerated particles during the relaxation phase of the flow.« less

Relaxation drag history of shock accelerated microparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bordoloi, Ankur D.; Martinez, Adam A.; Prestridge, Katherine

Experimental measurements of the displacements of shock accelerated microparticles from shortly after shock interaction to the particle relaxation time show time-dependent drag coefficients (more » $$C_{D}$$) that are much higher than those predicted by quasi-steady and unsteady drag models. Nylon particles with mean diameter of $$4~\\unicode[STIX]{x03BC}\\text{m}$$, accelerated by one-dimensional normal shocks (Mach number$$M_{s}=1.2$$, 1.3 and 1.4), have measured$$C_{D}$$values that follow a power-law behaviour. The drag is a function of the time-dependent Knudsen number,$$Kn^{\\ast }=M_{s}/Re_{p}$$, where the particle Reynolds number ($$Re_{p}$$) is calculated using the time-dependent slip velocity. Also, some portion of the drag can be attributed to quasi-steady forces, but the total drag cannot be predicted by current unsteady force models that are based on the Basset–Boussinesq–Oseen equation and pressure drag. The largest contribution to the total drag is the unsteady component ($$C_{D,us}$$) until the particle attains$$Kn^{\\ast }\\approx 0.5{-}1.0$$, then the unsteady contribution decays. The quasi-steady component ($$C_{D,qs}$$) increases almost linearly with$$Kn^{\\ast }$$, intersects the$$C_{D,us}$$at$$Kn^{\\ast }\\approx 2$$and becomes the primary contributor to the drag towards the end of the relaxation zone as$$Re_{p}\\rightarrow 0$$. Finally, there are currently no analytical models that are able to predict the nonlinear behaviour of the shock accelerated particles during the relaxation phase of the flow.« less

Experiments and analysis concerning the use of external burning to reduce aerospace vehicle transonic drag. Ph.D. Thesis - Maryland Univ., 1991

NASA Technical Reports Server (NTRS)

Trefny, Charles J.

1992-01-01

The external combustion of hydrogen to reduce transonic drag was investigated. A control volume analysis is developed and indicates that the specific impulse performance of external burning is competitive with other forms of airbreathing propulsion and depends on the fuel-air ratio, freestream Mach number, and the severity of the base drag. A method is presented for sizing fuel injectors for a desired fuel-air ratio in the unconfined stream. A two-dimensional Euler analysis is also presented which indicates that the total axial force generated by external burning depends on the total amount of energy input and is independent of the transverse and streamwise distribution of heat addition. Good agreement between the Euler and control volume analysis is demonstrated. Features of the inviscid external burning flowfield are discussed. Most notably, a strong compression forms at the sonic line within the burning stream which may induce separation of the plume and prevent realization of the full performance potential. An experimental program was conducted in a Mach 1.26 free-jet to demonstrate drag reduction on a simple expansion ramp geometry, and verify hydrogen-air stability limits at external burning conditions. Stable combustion appears feasible to Mach number of between 1.4 and 2 depending on the vehicle flight trajectory. Drag reduction is demonstrated on the expansion ramp at Mach 1.26; however, force levels showed little dependence on fuel pressure or altitude in contrast to control volume analysis predictions. Various facility interference mechanisms and scaling issues were studied and are discussed.

33 CFR 334.1280 - Bristol Bay, Alaska; air-to-air weapon range, Alaskan Air Command, U.S. Air Force.

Code of Federal Regulations, 2012 CFR

2012-07-01

... weapon range, Alaskan Air Command, U.S. Air Force. 334.1280 Section 334.1280 Navigation and Navigable... REGULATIONS § 334.1280 Bristol Bay, Alaska; air-to-air weapon range, Alaskan Air Command, U.S. Air Force. (a... enforced by the Commander, Alaskan Air Command, U.S. Air Force, Seattle, Washington, or such agencies as he...

33 CFR 334.1280 - Bristol Bay, Alaska; air-to-air weapon range, Alaskan Air Command, U.S. Air Force.

Code of Federal Regulations, 2013 CFR

2013-07-01

... weapon range, Alaskan Air Command, U.S. Air Force. 334.1280 Section 334.1280 Navigation and Navigable... REGULATIONS § 334.1280 Bristol Bay, Alaska; air-to-air weapon range, Alaskan Air Command, U.S. Air Force. (a... enforced by the Commander, Alaskan Air Command, U.S. Air Force, Seattle, Washington, or such agencies as he...

33 CFR 334.1280 - Bristol Bay, Alaska; air-to-air weapon range, Alaskan Air Command, U.S. Air Force.

Code of Federal Regulations, 2014 CFR

2014-07-01

... weapon range, Alaskan Air Command, U.S. Air Force. 334.1280 Section 334.1280 Navigation and Navigable... REGULATIONS § 334.1280 Bristol Bay, Alaska; air-to-air weapon range, Alaskan Air Command, U.S. Air Force. (a... enforced by the Commander, Alaskan Air Command, U.S. Air Force, Seattle, Washington, or such agencies as he...

33 CFR 334.1280 - Bristol Bay, Alaska; air-to-air weapon range, Alaskan Air Command, U.S. Air Force.

Code of Federal Regulations, 2010 CFR

2010-07-01

... weapon range, Alaskan Air Command, U.S. Air Force. 334.1280 Section 334.1280 Navigation and Navigable... REGULATIONS § 334.1280 Bristol Bay, Alaska; air-to-air weapon range, Alaskan Air Command, U.S. Air Force. (a... enforced by the Commander, Alaskan Air Command, U.S. Air Force, Seattle, Washington, or such agencies as he...

33 CFR 334.1280 - Bristol Bay, Alaska; air-to-air weapon range, Alaskan Air Command, U.S. Air Force.

Code of Federal Regulations, 2011 CFR

2011-07-01

... weapon range, Alaskan Air Command, U.S. Air Force. 334.1280 Section 334.1280 Navigation and Navigable... REGULATIONS § 334.1280 Bristol Bay, Alaska; air-to-air weapon range, Alaskan Air Command, U.S. Air Force. (a... enforced by the Commander, Alaskan Air Command, U.S. Air Force, Seattle, Washington, or such agencies as he...

Drop tower with no aerodynamic drag

NASA Technical Reports Server (NTRS)

Kendall, J. M., Jr.

1981-01-01

Cooling air accelerated to match velocity of falling object eliminates drag. 3 meter drop tower with suction fan and specific geometry causes air to accelerate downward at 1 g. Although cooling of molten material released from top is slow because surrounding air moves with it, drop remains nearly spherical.

A Computational and Experimental Study of Nonlinear Aspects of Induced Drag

NASA Technical Reports Server (NTRS)

Smith, Stephen C.

1996-01-01

Despite the 80-year history of classical wing theory, considerable research has recently been directed toward planform and wake effects on induced drag. Nonlinear interactions between the trailing wake and the wing offer the possibility of reducing drag. The nonlinear effect of compressibility on induced drag characteristics may also influence wing design. This thesis deals with the prediction of these nonlinear aspects of induced drag and ways to exploit them. A potential benefit of only a few percent of the drag represents a large fuel savings for the world's commercial transport fleet. Computational methods must be applied carefully to obtain accurate induced drag predictions. Trefftz-plane drag integration is far more reliable than surface pressure integration, but is very sensitive to the accuracy of the force-free wake model. The practical use of Trefftz plane drag integration was extended to transonic flow with the Tranair full-potential code. The induced drag characteristics of a typical transport wing were studied with Tranair, a full-potential method, and A502, a high-order linear panel method to investigate changes in lift distribution and span efficiency due to compressibility. Modeling the force-free wake is a nonlinear problem, even when the flow governing equation is linear. A novel method was developed for computing the force-free wake shape. This hybrid wake-relaxation scheme couples the well-behaved nature of the discrete vortex wake with viscous-core modeling and the high-accuracy velocity prediction of the high-order panel method. The hybrid scheme produced converged wake shapes that allowed accurate Trefftz-plane integration. An unusual split-tip wing concept was studied for exploiting nonlinear wake interaction to reduced induced drag. This design exhibits significant nonlinear interactions between the wing and wake that produced a 12% reduction in induced drag compared to an equivalent elliptical wing at a lift coefficient of 0.7. The

Dragging of inertial frames.

PubMed

Ciufolini, Ignazio

2007-09-06

The origin of inertia has intrigued scientists and philosophers for centuries. Inertial frames of reference permeate our daily life. The inertial and centrifugal forces, such as the pull and push that we feel when our vehicle accelerates, brakes and turns, arise because of changes in velocity relative to uniformly moving inertial frames. A classical interpretation ascribed these forces to acceleration relative to some absolute frame independent of the cosmological matter, whereas an opposite view related them to acceleration relative to all the masses and 'fixed stars' in the Universe. An echo and partial realization of the latter idea can be found in Einstein's general theory of relativity, which predicts that a spinning mass will 'drag' inertial frames along with it. Here I review the recent measurements of frame dragging using satellites orbiting Earth.

On hydrodynamics of drag and lift of the human arm.

PubMed

Gardano, Paola; Dabnichki, Peter

2006-01-01

The work presents results on drag and lift measurement conducted in a low speed wind tunnel on a replica of the entire human arm. The selected model positions were identical to those during purely rotational front crawl stroke in quasi-static conditions. A computational fluid dynamics model using Fluent showed close correspondence with the experimental results and confirmed the suitability of low speed wind tunnel for the drag and lift measurement in quasi-static conditions. The obtained profiles of the hydrodynamic forces were similar to the dynamic data presented in an earlier study suggesting that shape drag is a major contributing factor in propulsive force generation. The aim of this study was to underline the importance of the entire arm analysis, the elbow angle and a newly defined angle of attack representing the angle of shoulder rotation. It was found that both the maximum value of the drag force at 160 degrees elbow flexion angle and the momentum generated by it exceed the respective magnitudes for the fully extended arm. The latter is underlined by a prolonged plateau of near maximum drag that was obtained at shoulder angle range of 50-140 degrees suggesting that optimal arm configuration in terms of propulsive force generation requires elbow flexion. Furthermore it was found that drag trend is not consistent with the widely assumed and used sinus wave profile. A gap in the existing experimental research was filled as for the first time the entire arm lift and drag was measured across the entire stroke range.

Environmental Assessment for Air Force Research Laboratory Space Vehicles Integrated Experiments Division Office Space at Kirtland Air Force Base, Albuquerque, New Mexico

DTIC Science & Technology

2005-06-01

AIR FORCE RESEARCH LABORATORY SPACE VEHICLES INTEGRATED EXPERMENTS DIVISION OFFICE SPACE AT KIRTLAND AIR FORCE ... Kirtland Air Force Base (KAFB). The office building would house the Air Force Research Laboratory Space Vehicles Integrated Experiments Division...ADDRESS(ES) Air Force Research Laboratory ,Space Vehicles Directorate,3550 Aberdeen Ave. SE, Kirtland

Historical Lessons of Air Force Communications

DTIC Science & Technology

2010-12-01

AU/ACSC/ CUSTINE /AY10 AIR COMMAND AND STAFF COLLEGE AIR UNIVERSITY HISTORICAL LESSONS OF AIR FORCE COMMUNICATIONS...by Jay D. Custine , Civ, DAF A Research Report Submitted to the Faculty In Partial Fulfillment of the Graduation...Requirements Advisor: Lt Col Paul E. Griffith Maxwell Air Force Base, Alabama December 2010 AU/ACSC/ CUSTINE /AY10 ii

Drag reduction in channel flow using nonlinear control

NASA Technical Reports Server (NTRS)

Keefe, Laurence R.

1993-01-01

Two nonlinear control schemes have been applied to the problem of drag reduction in channel flow. Both schemes have been tested using numerical simulations at a mass flux Reynolds numbers of 4408, utilizing 2D nonlinear neutral modes for goal dynamics. The OGY-method, which requires feedback, reduces drag to 60-80 percent of the turbulent value at the same Reynolds number, and employs forcing only within a thin region near the wall. The H-method, or model-based control, fails to achieve any drag reduction when starting from a fully turbulent initial condition, but shows potential for suppressing or retarding laminar-to-turbulent transition by imposing instead a transition to a low drag, nonlinear traveling wave solution to the Navier-Stokes equation. The drag in this state corresponds to that achieved by the OGY-method. Model-based control requires no feedback, but in experiments to date has required the forcing be imposed within a thicker layer than the OGY-method. Control energy expenditures in both methods are small, representing less than 0.1 percent of the uncontrolled flow's energy.

Drag reduction - Jet breakup correlation with kerosene-based additives

NASA Technical Reports Server (NTRS)

Hoyt, J. W.; Altman, R. L.; Taylor, J. J.

1980-01-01

The drag-reduction effectiveness of a number of high-polymer additives dissolved in aircraft fuel has been measured in a turbulent-flow rheometer. These solutions were further subjected to high elongational stress and breakup forces in a jet discharging in air. The jet was photographed using a high-resolution camera with special lighting. The object of the work was to study the possible spray-suppression ability of high-polymer additives to aircraft fuel and to correlate this with the drag-reducing properties of the additives. It was found, in fact, that the rheometer results indicate the most effective spray-suppressing additives. Using as a measure the minimum polymer concentration to give a maximum friction-reducing effect, the order of effectiveness of eight different polymer additives as spray-suppressing agents was predicted. These results may find application in the development of antimisting additives for aircraft fuel which may increase fire safety in case of crash or accident.

Drag reduction by polymers in wall bounded turbulence.

PubMed

L'vov, Victor S; Pomyalov, Anna; Procaccia, Itamar; Tiberkevich, Vasil

2004-06-18

We elucidate the mechanism of drag reduction by polymers in turbulent wall-bounded flows: while momentum is produced at a fixed rate by the forcing, polymer stretching results in the suppression of momentum flux to the wall. On the basis of the equations of fluid mechanics we develop the phenomenology of the "maximum drag reduction asymptote" which is the maximum drag reduction attained by polymers. Based on Newtonian information only we demonstrate the existence of drag reduction, and with one experimental parameter we reach agreement with the experimental measurements.

Survival Analysis of US Air Force Officer Retention Rate

DTIC Science & Technology

2017-03-23

Air Force Institute of Technology AFIT Scholar Theses and Dissertations 3-23-2017 Survival Analysis of US Air Force Officer Retention Rate Courtney N...AIR UNIVERSITY AIR FORCE INSTITUTE OF TECHNOLOGY Wright-Patterson Air Force Base, Ohio DISTRIBUTION STATEMENT A. APPROVED FOR PUBLIC RELEASE...to the Faculty Department of Operational Sciences Graduate School of Engineering and Management Air Force Institute of Technology Air University

Rebalancing the Air Force: A Comprehensive Solution

DTIC Science & Technology

2011-02-16

the consequences can be significant. High Tempo (Figure 4) Lt Gen Charles E. Stenner , Jr., Chief of the Air Force Reserve, stated while...29 January 2010. 14 Lt Gen Charles E. Stenner Jr., Chief of the Air Force Reserve, ―Total Force Policy 21: A 21 st Century Framework for...Military Force Mix Decisions,‖ White Paper, 15 July 2010. 15 Lt Gen Charles E. Stenner Jr., Chief of the Air Force Reserve, ―Testimony Before the House

Experimental assessment of spanwise-oscillating dielectric electroactive surfaces for turbulent drag reduction in an air channel flow

NASA Astrophysics Data System (ADS)

Gatti, Davide; Güttler, Andreas; Frohnapfel, Bettina; Tropea, Cameron

2015-05-01

In the present work, wall oscillations for turbulent skin friction drag reduction are realized in an air turbulent duct flow by means of spanwise-oscillating active surfaces based on dielectric electroactive polymers. The actuator system produces spanwise wall velocity oscillations of 820 mm/s semi-amplitude at its resonance frequency of 65 Hz while consuming an active power of a few 100 mW. The actuators achieved a maximum integral drag reduction of 2.4 %. The maximum net power saving, budget of the power benefit and cost of the control, was measured for the first time with wall oscillations. Though negative, the net power saving is order of magnitudes higher than what has been estimated in previous studies. Two new direct numerical simulations of turbulent channel flow show that the finite size of the actuator only partially explains the lower values of integral drag reduction typically achieved in laboratory experiments compared to numerical simulations.

Air Force Historical Research Agency

Science.gov Websites

Command Capt Joseph J Merhar Jr collection Early Wright Brothers Flying Machines History of the 3rd Organizations Wings and Groups Squadrons and Flights Studies Documents Personal Papers Oral History Catalogue S. Fairchild Research Information Center Military Sites Air Force Link DefenseLINK Air Force History

32 CFR 855.22 - Air Force procedures.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 32 National Defense 6 2012-07-01 2012-07-01 false Air Force procedures. 855.22 Section 855.22 National Defense Department of Defense (Continued) DEPARTMENT OF THE AIR FORCE AIRCRAFT CIVIL AIRCRAFT USE... is located. AFI 13-201, Air Force Airspace Management, 8 lists the AFREPs and their addresses. The...

32 CFR 855.22 - Air Force procedures.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 32 National Defense 6 2014-07-01 2014-07-01 false Air Force procedures. 855.22 Section 855.22 National Defense Department of Defense (Continued) DEPARTMENT OF THE AIR FORCE AIRCRAFT CIVIL AIRCRAFT USE... is located. AFI 13-201, Air Force Airspace Management, 8 lists the AFREPs and their addresses. The...

32 CFR 631.15 - Air Force policy.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 32 National Defense 4 2014-07-01 2013-07-01 true Air Force policy. 631.15 Section 631.15 National...-Installation Operations (Military Patrols and Investigative Activities) and Policy § 631.15 Air Force policy. (a) Airmen, military and/or Department of the Air Force Civilian (DAFC) police performing off...

32 CFR 631.15 - Air Force policy.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 32 National Defense 4 2013-07-01 2013-07-01 false Air Force policy. 631.15 Section 631.15 National...-Installation Operations (Military Patrols and Investigative Activities) and Policy § 631.15 Air Force policy. (a) Airmen, military and/or Department of the Air Force Civilian (DAFC) police performing off...

32 CFR 631.15 - Air Force policy.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 32 National Defense 4 2011-07-01 2011-07-01 false Air Force policy. 631.15 Section 631.15 National...-Installation Operations (Military Patrols and Investigative Activities) and Policy § 631.15 Air Force policy. (a) Airmen, military and/or Department of the Air Force Civilian (DAFC) police performing off...

Design of a High Viscosity Couette Flow Facility for Patterned Surface Drag Measurements

NASA Astrophysics Data System (ADS)

Johnson, Tyler; Lang, Amy

2009-11-01

Direct drag measurements can be difficult to obtain with low viscosity fluids such as air or water. In this facility, mineral oil is used as the working fluid to increase the shear stress across the surface of experimental models. A mounted conveyor creates a flow within a plexiglass tank. The experimental model of a flat or patterned surface is suspended above a moving belt. Within the gap between the model and moving belt a Couette flow with a linear velocity profile is created. PIV measurements are used to determine the exact velocities and the Reynolds numbers for each experiment. The model is suspended by bars that connect to the pillow block housing of each bearing. Drag is measured by a force gauge connected to linear roller bearings that slide along steel rods. The patterned surfaces, initially consisting of 2-D cavities, are embedded in a plexiglass plate so as to keep the total surface area constant for each experiment. First, the drag across a flat plate is measured and compared to theoretical values for laminar Couette flow. The drag for patterned surfaces is then measured and compared to a flat plate.

Wing Tip Vortex Drag

NASA Technical Reports Server (NTRS)

Muirhead, V. U.

1975-01-01

Optimization of L/D through minimizing induced drag through a detailed flow study together with force, pressure and vorticity measurements is considered. Flow visualization with neutral helium bubbles provides an excellent means of observing the effects of configuration changes.

The drag forces exerted by lahar flows on a cylindrical pier: case study of post Mount Merapi eruptions

NASA Astrophysics Data System (ADS)

Faizien Haza, Zainul

2018-03-01

Debris flows of lahar flows occurred in post mount eruption is a phenomenon in which large quantities of water, mud, and gravel flow down a stream at a high velocity. It is a second stage of danger after the first danger of lava flows, pyroclastic, and toxic gases. The debris flow of lahar flows has a high density and also high velocity; therefore it has potential detrimental consequences against homes, bridges, and infrastructures, as well as loss of life along its pathway. The collision event between lahar flows and pier of a bridge is observed. The condition is numerically simulated using commercial software of computational fluid dynamic (CFD). The work is also conducted in order to investigate drag force generated during collision. Rheological data of lahar is observed through laboratory test of lahar model as density and viscosity. These data were used as the input data of the CFD simulation. The numerical model is involving two types of fluid: mud and water, therefore multiphase model is adopted in the current CFD simulation. The problem formulation is referring to the constitutive equations of mass and momentum conservation for incompressible and viscous fluid, which in perspective of two dimension (2D). The simulation models describe the situation of the collision event between lahar flows and pier of a bridge. It provides sequential view images of lahar flow impaction and the propagation trend line of the drag force coefficient values. Lahar flow analysis used non-dimensional parameter of Reynolds number. According to the results of numerical simulations, the drag force coefficients are in range 1.23 to 1.48 those are generated by value of flow velocity in range 11.11 m/s to 16.67 m/s.

Final Environmental Assessment for the First Air Force Air Operations Center, First Air Force Headquarters/Air Force Forces Center, and Highway 98 Overpass at Tyndall Air Force Base, Florida

DTIC Science & Technology

2004-01-01

to contact Sandra Veazey at (850) 595-8300 for additional information on asbestos issues. The Florida Department of Transportation (FDOT) supports...The notification form for the Department can be found at the following web address:. The Air Force is advised to contact Sandra Veazey at (850) 595

Air Force UAVs: The Secret History

DTIC Science & Technology

2010-07-01

iA Mitchell Institute Study i Air Force UAVs The Secret History A Mitchell Institute Study July 2010 By Thomas P. Ehrhard Report Documentation Page...DATES COVERED 00-00-2010 to 00-00-2010 4. TITLE AND SUBTITLE Air Force UAVs The Secret History 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c...opening phases of Operation Enduring Freedom in Afghanistan. By Thomas P. Ehrhard a miTchEll insTiTuTE sTudy July 2010 Air Force UAVs The Secret History

32 CFR 842.11 - Air Force claims organization.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 32 National Defense 6 2013-07-01 2013-07-01 false Air Force claims organization. 842.11 Section 842.11 National Defense Department of Defense (Continued) DEPARTMENT OF THE AIR FORCE CLAIMS AND LITIGATION ADMINISTRATIVE CLAIMS Functions and Responsibilities § 842.11 Air Force claims organization. Air...

32 CFR 842.11 - Air Force claims organization.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 32 National Defense 6 2010-07-01 2010-07-01 false Air Force claims organization. 842.11 Section 842.11 National Defense Department of Defense (Continued) DEPARTMENT OF THE AIR FORCE CLAIMS AND LITIGATION ADMINISTRATIVE CLAIMS Functions and Responsibilities § 842.11 Air Force claims organization. Air...

32 CFR 842.11 - Air Force claims organization.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 32 National Defense 6 2011-07-01 2011-07-01 false Air Force claims organization. 842.11 Section 842.11 National Defense Department of Defense (Continued) DEPARTMENT OF THE AIR FORCE CLAIMS AND LITIGATION ADMINISTRATIVE CLAIMS Functions and Responsibilities § 842.11 Air Force claims organization. Air...

The effects of radiation drag on radial, relativistic hydromagnetic winds

NASA Technical Reports Server (NTRS)

Li, Zhi-Yun; Begelman, Mitchell C.; Chiueh, Tzihong

1992-01-01

The effects of drag on an idealized relativistic MHD wind of radial geometry are studied. The astrophysical motivation is to understand the effects of radiation drag on the dynamics of a jet or wind passing through the intense radiation field of an accreting compact object. From a critical point analysis, it is found that a slow magnetosonic point can appear in a dragged flow even in the absence of gravitational force, as a result of a balance between the drag force and the combination of thermal pressure and centrifugal forces. As in the undragged case, the Alfven point does not impose any constraints on the flow. Although it is formally possible for a dragged flow to possess more than one fast magnetosonic point, it is shown that this is unlikely in practice. In the limit of a 'cold', centrifugally driven flow, it is shown that the fast magnetosonic point moves to infinite radius, just as in the drag-free case. For a given mass flux, the total energy output carried to infinity, and the final partition between the kinetic energy and the Poynting flux, are the same for the dragged and the drag-free flows. The main effects of radiation drag are to increase the amount of energy and angular momentum extracted from the source and to redistribute the regions where acceleration occurs in the flow. This is accomplished through the storage and release of magnetic energy, as a result of additional winding and compression of the field caused by the action of the drag. For a relativistic wind, the dissipated energy can exceed the final kinetic energy of the flow and may be comparable to the total flow energy (which is dominated by Poynting flux). The energy lost to radiation drag will appear as a Doppler-boosted beam of scattered radiation, which could dominate the background radiation if the flow is well-collimated.

Air Force Office of Scientific Research 1991 Research Highlights

DTIC Science & Technology

1991-01-01

research at Air Force Europe, allied victory in the Persian Gulf con- programs totaling nearly $300 million annual- laboratories . Air Force ...transitioning nological environment? laboratories and research centers into four research accomplishments for Air Force use. In this added role as... Air Force’s saries; maintaining a strong research Organizationally, AFOSR has also glo ehran gol per infrastructure among Air Force

View of Endeavour deploying its drag chute during STS-100's landing at Edwards AFB

NASA Image and Video Library

2001-05-01

STS100-S-020 (1 May 2001) --- The drag chute on the space shuttle Endeavour helps to slow the vehicle down as it eases to the completion of the STS-100 mission on a desert runway at Edwards Air Force Base in California. Touchdown occurred at 9:11 a.m. (PDT), May 1, 2001. Onboard the shuttle were six NASA astronauts and a cosmonaut representing Rosaviakosmos. Photo credit: NASA

Analog VLSI system for active drag reduction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gupta, B.; Goodman, R.; Jiang, F.

1996-10-01

In today`s cost-conscious air transportation industry, fuel costs are a substantial economic concern. Drag reduction is an important way to reduce costs. Even a 5% reduction in drag translates into estimated savings of millions of dollars in fuel costs. Drawing inspiration from the structure of shark skin, the authors are building a system to reduce drag along a surface. Our analog VLSI system interfaces with microfabricated, constant-temperature shear stress sensors. It detects regions of high shear stress and outputs a control signal to activate a microactuator. We are in the process of verifying the actual drag reduction by controlling microactuatorsmore » in wind tunnel experiments. We are encouraged that an approach similar to one that biology employs provides a very useful contribution to the problem of drag reduction. 9 refs., 21 figs.« less

Air Force Special Operations Command > Home > POTFF

Science.gov Websites

Air Force Special Operations Command Air Force Special Operations Command Join the Air Force Home Sheets AFSOC Senior Leaders AFSOC Heritage Units 1st Special Operations Wing 24th Special Operations Wing 27th Special Operations Wing 352nd Special Operations Wing 353rd Special Operations Group 492nd Special

The air forces on a systematic series of biplane and triplane cellule models

NASA Technical Reports Server (NTRS)

Munk, Max M

1927-01-01

The air forces on a systematic series of biplane and triplane cellule models are the subject of this report. The test consist in the determination of the lift, drag, and moment of each individual airfoil in each cellule, mostly with the same wing section. The magnitude of the gap and of the stagger is systematically varied; not, however, the decalage, which is zero throughout the tests. Certain check tests with a second wing section make the tests more complete and conclusions more convincing. The results give evidence that the present army and navy specifications for the relative lifts of biplanes are good. They furnish material for improving such specifications for the relative lifts of triplanes. A larger number of factors can now be prescribed to take care of different cases.

Stream-wise distribution of skin-friction drag reduction on a flat plate with bubble injection

NASA Astrophysics Data System (ADS)

Qin, Shijie; Chu, Ning; Yao, Yan; Liu, Jingting; Huang, Bin; Wu, Dazhuan

2017-03-01

To investigate the stream-wise distribution of skin-friction drag reduction on a flat plate with bubble injection, both experiments and simulations of bubble drag reduction (BDR) have been conducted in this paper. Drag reductions at various flow speeds and air injection rates have been tested in cavitation tunnel experiments. Visualization of bubble flow pattern is implemented synchronously. The computational fluid dynamics (CFD) method, in the framework of Eulerian-Eulerian two fluid modeling, coupled with population balance model (PBM) is used to simulate the bubbly flow along the flat plate. A wide range of bubble sizes considering bubble breakup and coalescence is modeled based on experimental bubble distribution images. Drag and lift forces are fully modeled based on applicable closure models. Both predicted drag reductions and bubble distributions are in reasonable concordance with experimental results. Stream-wise distribution of BDR is revealed based on CFD-PBM numerical results. In particular, four distinct regions with different BDR characteristics are first identified and discussed in this study. Thresholds between regions are extracted and discussed. And it is highly necessary to fully understand the stream-wise distribution of BDR in order to establish a universal scaling law. Moreover, mechanism of stream-wise distribution of BDR is analysed based on the near-wall flow parameters. The local drag reduction is a direct result of near-wall max void fraction. And the near-wall velocity gradient modified by the presence of bubbles is considered as another important factor for bubble drag reduction.

Reducing Air Force Fighter Pilot Shortages

DTIC Science & Technology

2015-12-31

that active-component fighter pilot requirements (particularly nonflying staff requirements) exceed its capacity to train and provide initial...pilots in the reserve components. This research was sponsored by four elements of the U.S. Air Force: the Deputy Chief of Staff for Operations (AF/A3...the Deputy Chief of Staff for Manpower, Personnel and Services (AF/A1); the Commander, Air Force Reserve Command (AFRC/CC); and the Director, Air

Air Force UAV’s: The Secret History

DTIC Science & Technology

2010-07-01

iA Mitchell Institute Study i Air Force UAVs The Secret History A Mitchell Institute Study July 2010 By Thomas P. Ehrhard Report Documentation Page...DATES COVERED 00-00-2010 to 00-00-2010 4. TITLE AND SUBTITLE Air Force UAVs The Secret History 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c... The Secret History 2 Air Force UAVs: The Secret History2 air Force uaVs: The secret history Has any airplane in the past decade captured the public

Air Force Audit Agency Management Information System

DTIC Science & Technology

1990-11-01

Support Directorate. AFAA/QL performs multilocation . Air Force-wide audits and issues reports to the SAF. It, however, specializes in the multibillion...USE ONLY (Leave blank) 2. REPORT DATE 3. REPORT TYPE AND DATES COVERED NOV 90 4. TITLE AND SUBTITLE S. FUNDING NUMBERS Air Force Audit Agency...appreciated. Mail them to: CADRE/RI, Building 1400, Maxwell AFB AL 36112-5532.• Air Force Audit Agency Management Hobbs Information System C 0* 0 0

Air Force Research Laboratory’s Focused Long Term Challenges

DTIC Science & Technology

2008-04-01

Air Force Research Laboratory ( AFRL ) mission is to provide support to the Air Force (AF) and the warfighters with... Air Force Research Laboratory’s Focused Long Term Challenges Leo J Rose Munitions Directorate, Air Force Research Laboratory , 101 W Eglin Blvd...This technology vision, which was born in our Air Force Research Laboratory , builds on the Air Force’s traditional kill

Simulating Electrophoresis with Discrete Charge and Drag

NASA Astrophysics Data System (ADS)

Mowitz, Aaron J.; Witten, Thomas A.

A charged asymmetric rigid cluster of colloidal particles in saline solution can respond in exotic ways to an electric field: it may spin or move transversely. These distinctive motions arise from the drag force of the neutralizing countercharge surrounding the cluster. Because of this drag, calculating the motion of arbitrary asymmetric objects with nonuniform charge is impractical by conventional methods. Here we present a new method of simulating electrophoresis, in which we replace the continuous object and the surrounding countercharge with discrete point-draggers, called Stokeslets. The balance of forces imposes a linear, self-consistent relation among the drag and Coulomb forces on the Stokeslets, which allows us to easily determine the object's motion via matrix inversion. By explicitly enforcing charge+countercharge neutrality, the simulation recovers the distinctive features of electrophoretic motion to few-percent accuracy using as few as 1000 Stokeslets. In particular, for uniformly charged objects, we observe the characteristic Smoluchowski independence of mobility on object size and shape. We then discuss electrophoretic motion of asymmetric objects, where our simulation method is particularly advantageous. This work is supported by a Grant from the US-Israel Binational Science Foundation.

NASA/Air Force Cost Model: NAFCOM

NASA Technical Reports Server (NTRS)

Winn, Sharon D.; Hamcher, John W. (Technical Monitor)

2002-01-01

The NASA/Air Force Cost Model (NAFCOM) is a parametric estimating tool for space hardware. It is based on historical NASA and Air Force space projects and is primarily used in the very early phases of a development project. NAFCOM can be used at the subsystem or component levels.

The Soviet Air Force and Strategic Bombing

DTIC Science & Technology

1999-04-01

to envision a British Air Force that could be totally divorced from some form of ground support role. Consequently, he saw an air campaign that would...CA: Presidio Press, 1986. Black, Steven K. The Icarus Illusion: Technology, Doctrine and the Soviet Air Force. Monterrey , CA, 1986. Cockburn, Andrew

32 CFR 631.15 - Air Force policy.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 32 National Defense 4 2010-07-01 2010-07-01 true Air Force policy. 631.15 Section 631.15 National... INVESTIGATIONS ARMED FORCES DISCIPLINARY CONTROL BOARDS AND OFF-INSTALLATION LIAISON AND OPERATIONS Off-Installation Operations (Military Patrols and Investigative Activities) and Policy § 631.15 Air Force policy...

Proceedings of Workshop on Atmospheric Density and Aerodynamic Drag Models for Air Force Operations Held at Air Force Geophysics Laboratory on 20-22 October 1987. Volume 2

DTIC Science & Technology

1990-02-13

spacecraft had near-polar orbits except for AE-C (680) and AE-E (190). This exten- sive lower thermosphere data set has been obtained over a wide...two satellite data sets is believed due mainly to uncertainties in the ballistic coefficients used to convert orbital drag measurements to atmospheric...eccentricity sun-synchronous orbit (1400/0200 LT) would provide data in local time-latitude regions not covered by the present data set . Coordination with

77 FR 33202 - Department of the Air Force

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-05

... DEPARTMENT OF DEFENSE Department of the Air Force Corrected Intent To Grant a Partially Exclusive Patent License AGENCY: The United States Air Force, DoD. SUMMARY: This notice replaces the one published... implements Public Law 96- 517, as amended; the Department of the Air Force announces its intention to grant...

Drag coefficients for loose reactor parts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shi, L.; Doster, J.M.; Mayo, C.W.

1997-12-01

Loose-part monitoring systems are capable of providing estimates of loose-part mass and energy as well as impact location. Additional information regarding potentially damaging loose parts can be obtained by estimating loose-part velocity on the basis of free motion dynamics within the flow. To estimate the loose-part velocity, the drag coefficient of the part must be known. Traditionally, drag coefficients of three-dimensional bodies are measured in wind tunnels, by towing in free air or liquids, and with drop tests. These methods have disadvantages with respect to measuring drag coefficients for loose parts in that they require a fixed orientation, or themore » flow field is inconsistent with the turbulent flow conditions found in reactor systems. Though drag coefficients for some regularly shaped objects can be found in the literature, many shapes representative of typical loose parts have not been investigated. In this work, drag coefficients are measured for typical loose-part shapes, including bolts, nuts, pins, and hand tools within the flow conditions expected in reactor coolant systems.« less

Air Force Technical Objective Document FY 87

DTIC Science & Technology

1985-12-01

Air Force Systems Command Edwards Air Force Base. Cal ifornia 93523-5000 NOTICES THIS DOCUMENT IS FOR INFORMATION AND GUIDANCE ONL Y This...acquisition of Air Foree weapon systems . Each Air Foree laboratory annually formulates Q Research and Technology (R& T) Pion in response to available...guidance based on USAF requirements, the identification of scientific and technological opportunities, and the needs of present and projected systems

Particular Solutions in Four body problem with solar wind drag

NASA Astrophysics Data System (ADS)

Kumari, Reena; Singh Kushvah, Badam

2012-07-01

To study the motion of a group of celestial objects/bodies interacting with each other under gravitational attraction. We formulated a four body problem with solar wind drag of one radiating body, rotating about their common center of mass with central configuration. We suppose that the governing forces of the motion of four body problems are mutual gravitational attractions of bodies and drag force of radiating body. Firstly, we derive the equations of motion using new co-ordinates for the four body problem. Again, we find the integrals of motions under different cases regarding to the mass of the bodies. Then we find the zero velocity surfaces and particular solutions. Finally, we examined the effect of solar wind drag on the motion of the four body problem. Keywords: Four Body Problem; Particular Solutions; Radiation Force; Zero Velocity Surfaces.

Air Force seal activities

NASA Astrophysics Data System (ADS)

Mayhew, Ellen R.

1994-07-01

Seal technology development is an important part of the Air Force's participation in the Integrated High Performance Turbine Engine Technology (IHPTET) initiative, the joint DOD, NASA, ARPA, and industry endeavor to double turbine engine capabilities by the turn of the century. Significant performance and efficiency improvements can be obtained through reducing internal flow system leakage, but seal environment requirements continue to become more extreme as the engine thermodynamic cycles advance towards these IHPTET goals. Brush seal technology continues to be pursued by the Air Force to reduce leakage at the required conditions. Likewise, challenges in engine mainshaft air/oil seals are also being addressed. Counter-rotating intershaft applications within the IHPTET initiative involve very high rubbing velocities. This viewgraph presentation briefly describes past and current seal research and development programs and gives a summary of seal applications in demonstrator and developmental engine testing.

Canadian Air Force Leadership and Command: Implications for the Human Dimension of Expeditionary Air Force Operations

DTIC Science & Technology

2006-11-01

Project Manager : CSA: Angela Febbraro The scientific or technical validity of this Contract Report is entirely the responsibility of the...ways, for example, in leadership styles and command arrangements. Unfortunately for the Canadian Air Force, very little has been written about how its...culture and professional working environment have influenced the development of unique Canadian air force leadership styles and command

Highly accurate analytic formulae for projectile motion subjected to quadratic drag

NASA Astrophysics Data System (ADS)

Turkyilmazoglu, Mustafa

2016-05-01

The classical phenomenon of motion of a projectile fired (thrown) into the horizon through resistive air charging a quadratic drag onto the object is revisited in this paper. No exact solution is known that describes the full physical event under such an exerted resistance force. Finding elegant analytical approximations for the most interesting engineering features of dynamical behavior of the projectile is the principal target. Within this purpose, some analytical explicit expressions are derived that accurately predict the maximum height, its arrival time as well as the flight range of the projectile at the highest ascent. The most significant property of the proposed formulas is that they are not restricted to the initial speed and firing angle of the object, nor to the drag coefficient of the medium. In combination with the available approximations in the literature, it is possible to gain information about the flight and complete the picture of a trajectory with high precision, without having to numerically simulate the full governing equations of motion.

Air Force and Diversity: The Awkward Embrace

DTIC Science & Technology

2013-02-14

Streeter is a U.S. Air Force intelligence officer assigned to the Air War College, Air University, Maxwell AFB, AL. She graduated from the United States...future leaders.” Princeton University Office of Human Resources Web site; Wilson et al, Grooming Top Leaders, 4. 28 45. Dr Fil J . Arenas...Air Force Diversity Strategic Roadmap (2012), 14. 86. Dr. Fil J . Arenas (Associate Professor, Organizational Leadership Studies, Squadron

Air Force Weapons Laboratory Computational Requirements for 1976 Through 1980

DTIC Science & Technology

1976-01-01

Air Force Weapons Laboratory , Attn: DYS, Kirtland AFB, NM 87117...final report was prepared by the Air Force Weapons Laboratory , Kirtland Air Force Base, New Mexico under Job Order 06CB. Dr. Clifford E. Rhoades, Jr... Force Base, New Mexico 87117 62601F, 06CB II. CONTROLLING OFFICE NAME AND ADDRESS Ai"- Force Weapons Laboratory / Jan 1076 Kirtland Air Force Base,

Securing the High Ground: Dominant Combat Air Force for America. 2008 Combat Air Force Strategic Plan

DTIC Science & Technology

2008-07-28

continue to be beyond our technical ability to realize aggresively pursue advanced technical solutions to stay at the leading edge of technological...inherent to each caf Way and to seek continual improvement through exploration of innovative concepts, advanced capabilities, game -changing...available online at the air force portal: https://wwwd.my.af.mil/afknprod/strat_plan COMBAT AIR FORCE STRATEGIC PLAN Points of Contact securing the high

Drag and Cooling with Various Forms of Cowling for a "Whirlwind" Radial Air-cooled Engine II

NASA Technical Reports Server (NTRS)

Weick, Fred E

1930-01-01

This report gives the results of the second portion of an investigation in the twenty-foot Propeller Research Tunnel of the National Advisory Committee for Aeronautics, on the cowling and cooling of a "Whirlwind" J-5 radial air-cooled engine. The first portion pertains to tests with a cabin fuselage. This report covers tests with several forms of cowling, including conventional types, individual fairings behind the cylinders, individual hoods over the over the cylinders, and the new N. A. C. A. complete cowling, all on an open cockpit fuselage. Drag tests were also made with a conventional engine nacelle, and with a nacelle having the new complete cowling. In the second part of the investigation the results found in the first part were substantiated. It was also found that the reduction in drag with the complete cowling over that with conventional cowling is greater with the smaller bodies than with the cabin fuselage; in fact, the gain in the case of the completely cowled nacelle is over twice that with the cabin fuselage. The individual fairings and hoods did not prove effective in reducing the drag. The results of flight tests on AT-5A airplane has been analyzed and found to agree very well with the results of the wind tunnel tests. (author)

Cognitive Evaluation of Israeli Air Force Pilot Cadets.

PubMed

Gordon, Shirley; Goren, Chen; Carmon, Erez; Shelef, Leah

2017-04-01

In aviation psychology, there is a constant need for the cognitive evaluation of pilots as part of operational fitness and safety criteria. A cross-sectional study with comparison between the performance of Israeli Air Force pilot cadets (N = 318) and U.S. Air Force pilot training candidates (N = 512) as assessed by a cognitive battery was undertaken. The data of the comparison group was collected from Callister, King, and Retzlaff, as published in 1996. In general, the means in the three components composing the battery-speed, accuracy, and throughput variables-indicated that the Israeli Air Force pilot cadets' scores were higher than those of the U.S. Air Force pilot candidates' scores in 50 of 53 variables. Nonsignificant differences were found in Accuracy of shifting attention-arrow color (SATAC), pathfinder-combined (PFC), and pathfinder-letter (PFL). The difference in performance between the two groups may be due to differences in population characteristics. However, these results need to be considered cautiously, as the groups were sampled at a sizeable time gap (1996 for the U.S. Air Force vs. 2013 for the Israeli Air Force), with each time period characterized by different cultural and technological influences.Gordon S, Goren C, Carmon E, Shelef L. Cognitive evaluation of Israeli Air Force pilot cadets. Aerosp Med Hum Perform. 2017; 88(4):392-398.

Chief of Staff of the Air Force

Science.gov Websites

Speeches Archive Former AF Top 3 Viewpoints and Speeches Air Force Warrior Games 2017 Events 2018 Air Force Strategic Documents Desert Storm 25th Anniversary Observances DoD Warrior Games Portraits in Courage

Chief Master Sergeant of the Air Force

Science.gov Websites

Speeches Archive Former AF Top 3 Viewpoints and Speeches Air Force Warrior Games 2017 Events 2018 Air Force Strategic Documents Desert Storm 25th Anniversary Observances DoD Warrior Games Portraits in Courage

A Delicate Balance: Hovering Balloons in an Air Stream

ERIC Educational Resources Information Center

Gluck, Paul

2006-01-01

Science museums and popular physics shows often exhibit a blower in whose air stream a ball is held hovering in equilibrium some distance above the jet's orifice. The weight of the ball, "mg," is balanced by the drag force of the turbulent air stream, often written as ?Cv[superscript 2]A, where "?" and "v" are the…

Air Force Integrated Personnel and Pay System (AFIPPS)

DTIC Science & Technology

2016-03-01

2016 Major Automated Information System Annual Report Air Force Integrated Personnel and Pay System (AFIPPS) Defense Acquisition Management...DSN Fax: 665-1207 Date Assigned: February 1, 2016 Program Information Program Name Air Force Integrated Personnel and Pay System (AFIPPS) DoD...therefore, no Original Estimate has been established. AFIPPS 2016 MAR UNCLASSIFIED 4 Program Description Air Force Integrated Personnel and Pay

Evaluation of WRF Simulations With Different Selections of Subgrid Orographic Drag Over the Tibetan Plateau

NASA Astrophysics Data System (ADS)

Zhou, X.; Beljaars, A.; Wang, Y.; Huang, B.; Lin, C.; Chen, Y.; Wu, H.

2017-09-01

Weather Research and Forecasting (WRF) simulations with different selections of subgrid orographic drag over the Tibetan Plateau have been evaluated with observation and ERA-Interim reanalysis. Results show that the subgrid orographic drag schemes, especially the turbulent orographic form drag (TOFD) scheme, efficiently reduce the 10 m wind speed bias and RMS error with respect to station measurements. With the combination of gravity wave, flow blocking and TOFD schemes, wind speed is simulated more realistically than with the individual schemes only. Improvements are also seen in the 2 m air temperature and surface pressure. The gravity wave drag, flow blocking drag, and TOFD schemes combined have the smallest station mean bias (-2.05°C in 2 m air temperature and 1.27 hPa in surface pressure) and RMS error (3.59°C in 2 m air temperature and 2.37 hPa in surface pressure). Meanwhile, the TOFD scheme contributes more to the improvements than the gravity wave drag and flow blocking schemes. The improvements are more pronounced at low levels of the atmosphere than at high levels due to the stronger drag enhancement on the low-level flow. The reduced near-surface cold bias and high-pressure bias over the Tibetan Plateau are the result of changes in the low-level wind components associated with the geostrophic balance. The enhanced drag directly leads to weakened westerlies but also enhances the a-geostrophic flow in this case reducing (enhancing) the northerlies (southerlies), which bring more warm air across the Himalaya Mountain ranges from South Asia (bring less cold air from the north) to the interior Tibetan Plateau.

Analysis of Drag Reduction Methods and Mechanisms of Turbulent.

PubMed

Yunqing, Gu; Tao, Liu; Jiegang, Mu; Zhengzan, Shi; Peijian, Zhou

2017-01-01

Turbulent flow is a difficult issue in fluid dynamics, the rules of which have not been totally revealed up to now. Fluid in turbulent state will result in a greater frictional force, which must consume great energy. Therefore, it is not only an important influence in saving energy and improving energy utilization rate but also an extensive application prospect in many fields, such as ship domain and aerospace. Firstly, bionic drag reduction technology is reviewed and is a hot research issue now, the drag reduction mechanism of body surface structure is analyzed, such as sharks, earthworms, and dolphins. Besides, we make a thorough study of drag reduction characteristics and mechanisms of microgrooved surface and compliant wall. Then, the relevant drag reduction technologies and mechanisms are discussed, focusing on the microbubbles, the vibrant flexible wall, the coating, the polymer drag reduction additives, superhydrophobic surface, jet surface, traveling wave surface drag reduction, and the composite drag reduction methods. Finally, applications and advancements of the drag reduction technology in turbulence are prospected.

Analysis of Drag Reduction Methods and Mechanisms of Turbulent

PubMed Central

Tao, Liu; Jiegang, Mu; Zhengzan, Shi; Peijian, Zhou

2017-01-01

Turbulent flow is a difficult issue in fluid dynamics, the rules of which have not been totally revealed up to now. Fluid in turbulent state will result in a greater frictional force, which must consume great energy. Therefore, it is not only an important influence in saving energy and improving energy utilization rate but also an extensive application prospect in many fields, such as ship domain and aerospace. Firstly, bionic drag reduction technology is reviewed and is a hot research issue now, the drag reduction mechanism of body surface structure is analyzed, such as sharks, earthworms, and dolphins. Besides, we make a thorough study of drag reduction characteristics and mechanisms of microgrooved surface and compliant wall. Then, the relevant drag reduction technologies and mechanisms are discussed, focusing on the microbubbles, the vibrant flexible wall, the coating, the polymer drag reduction additives, superhydrophobic surface, jet surface, traveling wave surface drag reduction, and the composite drag reduction methods. Finally, applications and advancements of the drag reduction technology in turbulence are prospected. PMID:29104425

Helicopter hub fairing and pylon interference drag

NASA Technical Reports Server (NTRS)

Graham, D. R.; Sung, D. Y.; Young, L. A.; Louie, A. W.; Stroub, R. H.

1989-01-01

A wind tunnel test was conducted to study the aerodynamics of helicopter hub and pylon fairings. The test was conducted in the 7-by 10 Foot Subsonic Wind Tunnel (Number 2) at Ames Research Center using a 1/5-scale XH-59A fuselage model. The primary focus of the test was on the rotor hub fairing and pylon mutual interference drag. Parametric studies of pylon and hub fairing geometry were also conducted. This report presents the major findings of the test as well as tabulated force and moment data, flow visualization photographs, and graphical presentations of the drag data. The test results indicate that substantial drag reduction can be attained through the use of a cambered hub fairing with circular arc upper surface and flat lower surface. Furthermore, a considerable portion of the overall drag reduction is attributed to the reduction in the hub-on-pylon interference drag. It is also observed that the lower surface curvature of the fairing has a strong influence on the hub fairing and on pylon interference drag. However, the drag reduction benefit that was obtained by using the cambered hub fairing with a flat lower surface was adversely affected by the clearance between the hub fairing and the pylon.

Effects of plasma drag on low Earth orbiting satellites due to solar forcing induced perturbations and heating

NASA Astrophysics Data System (ADS)

Nwankwo, Victor U. J.; Chakrabarti, Sandip K.; Weigel, Robert S.

2015-07-01

The upper atmosphere changes significantly in temperature, density and composition as a result of solar cycle variations, which causes severe storms and flares, and increases in the amount of absorbed solar radiation from solar energetic events. Satellite orbits are consequently affected by this process, especially those in low Earth orbit (LEO). In this paper, we present a model of atmospheric drag effects on the trajectory of two hypothetical LEO satellites of different ballistic coefficients, initially injected at h = 450 km. We investigate long-term trends of atmospheric drag on LEO satellites due to solar forcing induced atmospheric perturbations and heating at different phases of the solar cycle, and during short intervals of strong geomagnetic disturbances or magnetic storms. We show dependence of orbital decay on the severity of both solar cycle and phase and the extent of geomagnetic perturbations. The result of the model compares well with observed decay profile of some existing LEO satellites and provide a justification of the theoretical considerations used here.

Pacific Air Forces > Home

Science.gov Websites

headquarters staff at Joint Base Pearl Harbor-Hickam, Hawaii, May 16, 2016. U.S. Air Force Maj. Gen. Russell L Tarin Punsri (center left), and attendees pose for a photo in the Courtyard of Heroes at Joint Base commander's call at Misawa Air Base, Japan, May 11, 2018. The general highlighted the strategic importance of

Determination of the Drag Resistance Coefficients of Different Vehicles

ERIC Educational Resources Information Center

Fahsl, Christoph; Vogt, Patrik

2018-01-01

While it has been demonstrated how air resistance could be analyzed by using mobile devices, this paper demonstrates a method of how to determine the drag resistance coefficient "c" of a commercial automobile by using the acceleration sensor of a smartphone or tablet. In an academic context, the drag resistance is often mentioned, but…

On the diverse roles of fluid dynamic drag in animal swimming and flying

PubMed Central

2018-01-01

Questions of energy dissipation or friction appear immediately when addressing the problem of a body moving in a fluid. For the most simple problems, involving a constant steady propulsive force on the body, a straightforward relation can be established balancing this driving force with a skin friction or form drag, depending on the Reynolds number and body geometry. This elementary relation closes the full dynamical problem and sets, for instance, average cruising velocity or energy cost. In the case of finite-sized and time-deformable bodies though, such as flapping flyers or undulatory swimmers, the comprehension of driving/dissipation interactions is not straightforward. The intrinsic unsteadiness of the flapping and deforming animal bodies complicates the usual application of classical fluid dynamic forces balance. One of the complications is because the shape of the body is indeed changing in time, accelerating and decelerating perpetually, but also because the role of drag (more specifically the role of the local drag) has two different facets, contributing at the same time to global dissipation and to driving forces. This causes situations where a strong drag is not necessarily equivalent to inefficient systems. A lot of living systems are precisely using strong sources of drag to optimize their performance. In addition to revisiting classical results under the light of recent research on these questions, we discuss in this review the crucial role of drag from another point of view that concerns the fluid–structure interaction problem of animal locomotion. We consider, in particular, the dynamic subtleties brought by the quadratic drag that resists transverse motions of a flexible body or appendage performing complex kinematics, such as the phase dynamics of a flexible flapping wing, the propagative nature of the bending wave in undulatory swimmers, or the surprising relevance of drag-based resistive thrust in inertial swimmers. PMID:29445037

Progress in Frictional Drag Reduction Summer 1971 to Summer 1972

DTIC Science & Technology

1973-01-01

directed at achieving •nprovey sea wnd Air ii .- wa for•ted in March 1967 by merging the David Taylor Madei Basin at CizIeniAir, ’ýplr/t]La with ihe...means. Greskovich and Shrier (50) show that polymers also provide drag reduction in two-phase systems such as gas-liquid systems. Medical applications...May 1971). 50. Greskovich, E. J. and A. J. Shrier , "Drag Reduction in Two- Phase Flows," Industrial and Engineering Chemistry (Fundamentals), Vol. 10

United States Air Force Wipe Solvent Testing

NASA Technical Reports Server (NTRS)

Hornung, Steven D.; Beeson, Harold D.

2000-01-01

The Wright-Patterson Air Force Base (WPAFB), as part of the Air Force Material Command, requested that NASA Johnson Space Center (JSC) White Sands Test Facility (WSTF) conduct testing and analyses in support of the United States Air Force Wipe Solvent Development Project. The purpose of the wipe solvent project is to develop an alternative to be used by Air Force flight line and maintenance personnel for the wipe cleaning of oxygen equipment. This report provides material compatibility, liquid oxygen (LOX) mechanical impact, autogenous ignition temperature (AIT), and gauge cleaning test data for some of the currently available solvents that may be used to replace CFC-113 and methyl chloroform. It provides data from previous WSTF test programs sponsored by the Naval Sea Systems Command, the Kennedy Space Center, and other NASA programs for the purpose of assisting WP AFB in identifying the best alternative solvents for validation testing.

Simulation of Mean Flow and Turbulence over a 2D Building Array Using High-Resolution CFD and a Distributed Drag Force Approach

DTIC Science & Technology

2016-06-16

procedure. The predictive capabilities of the high-resolution computational fluid dynamics ( CFD ) simulations of urban flow are validated against a very...turbulence over a 2D building array using high-resolution CFD and a distributed drag force approach a Department of Mechanical Engineering, University

U.S. Air Force Doctrine: A Perspective

DTIC Science & Technology

1990-01-01

of Air Power." This document provided the independence long desired by proponents of a separate air force. It recognized the role of air superiority...guidance. First, AFM 1-1 fails to adequately address the corduct of war across the spectrum of conflict. The document tails to address the Vietnam war...have made it possible--in deed necessary-to update the doctrine;" "Air Force puts 3-2 in a class by itself and has given it superstar status billing

77 FR 55465 - US Air Force Exclusive Patent License

Federal Register 2010, 2011, 2012, 2013, 2014

2012-09-10

...: Air Force Research Laboratory Information Directorate, Rome, New York, Department of the Air Force.... Written objections should be sent to: Air Force Research Laboratory, Office of the Staff Judge Advocate, AFRL/RIJ, 26 Electronic Parkway, Rome, New York 13441-4514. Telephone: (315) 330-2087; Facsimile (315...

Gravitational mass attraction measurement for drag-free references

NASA Astrophysics Data System (ADS)

Swank, Aaron J.

Exciting new experiments in gravitational physics are among the proposed future space science missions around the world. Such future space science experiments include gravitational wave observatories, which require extraordinarily precise instruments for gravitational wave detection. In fact, future space-based gravitational wave observatories require the use of a drag free reference sensor, which is several orders of magnitude more precise than any drag free satellite launched to date. With the analysis methods and measurement techniques described in this work, there is one less challenge associated with achieving the high-precision drag-free satellite performance levels required by gravitational wave observatories. One disturbance critical to the drag-free performance is an acceleration from the mass attraction between the spacecraft and drag-free reference mass. A direct measurement of the gravitational mass attraction force is not easily performed. Historically for drag-free satellite design, the gravitational attraction properties were estimated by using idealized equations between a point mass and objects of regular geometric shape with homogeneous density. Stringent requirements are then placed on the density distribution and fabrication tolerances for the drag-free reference mass and satellite components in order to ensure that the allocated gravitational mass attraction disturbance budget is not exceeded due to the associated uncertainty in geometry and mass properties. Yet, the uncertainty associated with mass properties and geometry generate an unacceptable uncertainty in the mass attraction calculation, which make it difficult to meet the demanding drag-free performance requirements of future gravitational wave observatories. The density homogeneity and geometrical tolerances required to meet the overall drag-free performance can easily force the use of special materials or manufacturing processes, which are impractical or not feasible. The focus of

Combat Squadrons of the Air Force, World War II,

DTIC Science & Technology

1982-01-01

1952. Inactivated on 1 Jul 1957. Redes- of a paddle wheel river boat, Air Force ignated 7o2d Troop Carrier Squadron blue, the windows lighted Air Force ...782d Bombard- hitched to a red wagon with wheels red, ment Squadron (Heavy) on 19 May hub yellow, tires and axles black, the 1943. Activated on 1 Aug...AD-A128 026 COMBAT SQUADRONS OF TOE AIR FORCE WORLD WAR IU) 1OFFICEOF AIR FORCE HISTORY WASHINGTON DC M MAURER UNCLASSIFIED F/G 15/7 NL

Turbulence and turbulent drag reduction in swirling flow: Inertial versus viscous forcing

NASA Astrophysics Data System (ADS)

Burnishev, Yuri; Steinberg, Victor

2015-08-01

We report unexpected results of a drastic difference in the transition to fully developed turbulent and turbulent drag reduction (TDR) regimes and in their properties in a von Karman swirling flow with counter-rotating disks of water-based polymer solutions for viscous (by smooth disks) as well as inertial (by bladed disks) forcing and by tracking just torque Γ (t ) and pressure p (t ) . For the viscous forcing, just a single TDR regime is found with the transition values of the Reynolds number (Re) Recturb=RecTDR≃(4.8 ±0.2 ) ×105 independent of ϕ , whereas for the inertial forcing two turbulent regimes are revealed. The first transition is to fully developed turbulence, and the second one is to the TDR regime with both Recturb and RecTDR depending on polymer concentration ϕ . Both regimes differ by the values of Cf and Cp, by the scaling exponents of the fundamental turbulent characteristics, by the nonmonotonic dependencies of skewness and flatness of the pressure PDFs on Re, and by the different frequency power spectra of p with the different dependencies of the main vortex peak frequency in the p power spectra on ϕ and Re. Thus our experimental results show the transition to the TDR regime in a von Karman swirling flow for the viscous and inertial forcings in a sharp contrast to the recent experiments [Phys. Fluids 10, 426 (1998), 10.1063/1.869532; Phys. Rev. E 47, R28(R) (1993), 10.1103/PhysRevE.47.R28; and J. Phys.: Condens. Matter 17, S1195 (2005), 10.1088/0953-8984/17/14/008] where the transition to TDR is observed in the same swirling flow with counter-rotating disks only for the viscous forcing. The latter result has led its authors to the wrong conclusion that TDR is a solely boundary effect contrary to the inertial forcing associated with the bulk effect, and this conception is currently rather widely accepted in literature.

Turbulence and turbulent drag reduction in swirling flow: Inertial versus viscous forcing.

PubMed

Burnishev, Yuri; Steinberg, Victor

2015-08-01

We report unexpected results of a drastic difference in the transition to fully developed turbulent and turbulent drag reduction (TDR) regimes and in their properties in a von Karman swirling flow with counter-rotating disks of water-based polymer solutions for viscous (by smooth disks) as well as inertial (by bladed disks) forcing and by tracking just torque Γ(t) and pressure p(t) . For the viscous forcing, just a single TDR regime is found with the transition values of the Reynolds number (Re) Re turb c =Re TDR c ≃(4.8±0.2)×10(5) independent of ϕ , whereas for the inertial forcing two turbulent regimes are revealed. The first transition is to fully developed turbulence, and the second one is to the TDR regime with both Re turb c and Re TDR c depending on polymer concentration ϕ . Both regimes differ by the values of C f and C p , by the scaling exponents of the fundamental turbulent characteristics, by the nonmonotonic dependencies of skewness and flatness of the pressure PDFs on Re, and by the different frequency power spectra of p with the different dependencies of the main vortex peak frequency in the p power spectra on ϕ and Re. Thus our experimental results show the transition to the TDR regime in a von Karman swirling flow for the viscous and inertial forcings in a sharp contrast to the recent experiments [Phys. Fluids 10, 426 (1998); Phys. Rev. E 47, R28(R) (1993); and J. Phys.: Condens. Matter 17, S1195 (2005)] where the transition to TDR is observed in the same swirling flow with counter-rotating disks only for the viscous forcing. The latter result has led its authors to the wrong conclusion that TDR is a solely boundary effect contrary to the inertial forcing associated with the bulk effect, and this conception is currently rather widely accepted in literature.

Air Force Strategy Study 2020-2030

DTIC Science & Technology

2011-01-01

shocks (also known as “black swans”), having 2 │ introduction the potential to radically alter the utility of the capability, as a way of highlighting... utilized by its expeditionary air units.”5 The Air Force must present strategic and operational options along with forces capable of operating and...Emer- gency Management Agency (FEMA) regional staffs, in part representing the service and USNORTHCOM. The imagery analysts’ utility is largely due

Advanced Robotics for Air Force Operations

DTIC Science & Technology

1989-06-01

evaluated current and potential uses of advanced robotics to support Air Force systems, (2) recommended the most effective aplications of advanced robotics...manpower. Such a robot system would The boom would not only transfer fuel, be considerably more mobile and effi- 10 ADVANCED ROBOTICS FOR AIR FORCE...increased manpower resources in war tive clothing reduce vision, hearing, and make this an attractive potential appli- mobility , which further reduce

Modeling the effects of small turbulent scales on the drag force for particles below and above the Kolmogorov scale

NASA Astrophysics Data System (ADS)

Gorokhovski, Mikhael; Zamansky, Rémi

2018-03-01

Consistently with observations from recent experiments and DNS, we focus on the effects of strong velocity increments at small spatial scales for the simulation of the drag force on particles in high Reynolds number flows. In this paper, we decompose the instantaneous particle acceleration in its systematic and residual parts. The first part is given by the steady-drag force obtained from the large-scale energy-containing motions, explicitly resolved by the simulation, while the second denotes the random contribution due to small unresolved turbulent scales. This is in contrast with standard drag models in which the turbulent microstructures advected by the large-scale eddies are deemed to be filtered by the particle inertia. In our paper, the residual term is introduced as the particle acceleration conditionally averaged on the instantaneous dissipation rate along the particle path. The latter is modeled from a log-normal stochastic process with locally defined parameters obtained from the resolved field. The residual term is supplemented by an orientation model which is given by a random walk on the unit sphere. We propose specific models for particles with diameter smaller and larger size than the Kolmogorov scale. In the case of the small particles, the model is assessed by comparison with direct numerical simulation (DNS). Results showed that by introducing this modeling, the particle acceleration statistics from DNS is predicted fairly well, in contrast with the standard LES approach. For the particles bigger than the Kolmogorov scale, we propose a fluctuating particle response time, based on an eddy viscosity estimated at the particle scale. This model gives stretched tails of the particle acceleration distribution and dependence of its variance consistent with experiments.

The Air Force and the Cold War

DTIC Science & Technology

2005-09-01

March 2001. 49An Air Force Association Special Report 49An Air Force As ociation Special Report CANAN , James. War in Space. Harper & Row, 1982...Press, 1989. GARDNER, Lloyd C. Spheres of Influence: The Great Powers Partition Europe, From Munich to Yalta. Ivan R. Dee Publisher, 1993. GARTHOFF

Forecasting Foreign Currency Exchange Rates for Air Force Budgeting

DTIC Science & Technology

2015-03-26

FORECASTING FOREIGN CURRENCY EXCHANGE RATES FOR AIR FORCE BUDGETING THESIS MARCH 2015...States. AFIT-ENV-MS-15-M-178 FORECASTING FOREIGN CURRENCY EXCHANGE RATES FOR AIR FORCE BUDGETING THESIS Presented to the Faculty...FORECASTING FOREIGN CURRENCY EXCHANGE RATES FOR AIR FORCE BUDGETING Nicholas R. Gardner, BS Captain, USAF Committee Membership: Lt Col Jonathan

32 CFR 644.516 - Clearance of Air Force lands.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 32 National Defense 4 2010-07-01 2010-07-01 true Clearance of Air Force lands. 644.516 Section 644... Excess Land and Improvements § 644.516 Clearance of Air Force lands. The Chief of Engineers has no responsibility for inspecting or clearing excess Air Force land of explosives or chemical/biological contaminants...

Bondi or not Bondi: the impact of resolution on accretion and drag force modelling for supermassive black holes

NASA Astrophysics Data System (ADS)

Beckmann, R. S.; Slyz, A.; Devriendt, J.

2018-07-01

Whilst in galaxy-size simulations, supermassive black holes (SMBHs) are entirely handled by sub-grid algorithms, computational power now allows the accretion radius of such objects to be resolved in smaller scale simulations. In this paper, we investigate the impact of resolution on two commonly used SMBH sub-grid algorithms; the Bondi-Hoyle-Lyttleton (BHL) formula for accretion on to a point mass, and the related estimate of the drag force exerted on to a point mass by a gaseous medium. We find that when the accretion region around the black hole scales with resolution, and the BHL formula is evaluated using local mass-averaged quantities, the accretion algorithm smoothly transitions from the analytic BHL formula (at low resolution) to a supply-limited accretion scheme (at high resolution). However, when a similar procedure is employed to estimate the drag force, it can lead to significant errors in its magnitude, and/or apply this force in the wrong direction in highly resolved simulations. At high Mach numbers and for small accretors, we also find evidence of the advective-acoustic instability operating in the adiabatic case, and of an instability developing around the wake's stagnation point in the quasi-isothermal case. Moreover, at very high resolution, and Mach numbers above M_∞ ≥ 3, the flow behind the accretion bow shock becomes entirely dominated by these instabilities. As a result, accretion rates on to the black hole drop by about an order of magnitude in the adiabatic case, compared to the analytic BHL formula.

Bondi or not Bondi: the impact of resolution on accretion and drag force modelling for Supermassive Black Holes

NASA Astrophysics Data System (ADS)

Beckmann, R. S.; Slyz, A.; Devriendt, J.

2018-04-01

Whilst in galaxy-size simulations, supermassive black holes (SMBH) are entirely handled by sub-grid algorithms, computational power now allows the accretion radius of such objects to be resolved in smaller scale simulations. In this paper, we investigate the impact of resolution on two commonly used SMBH sub-grid algorithms; the Bondi-Hoyle-Lyttleton (BHL) formula for accretion onto a point mass, and the related estimate of the drag force exerted onto a point mass by a gaseous medium. We find that when the accretion region around the black hole scales with resolution, and the BHL formula is evaluated using local mass-averaged quantities, the accretion algorithm smoothly transitions from the analytic BHL formula (at low resolution) to a supply limited accretion (SLA) scheme (at high resolution). However, when a similar procedure is employed to estimate the drag force it can lead to significant errors in its magnitude, and/or apply this force in the wrong direction in highly resolved simulations. At high Mach numbers and for small accretors, we also find evidence of the advective-acoustic instability operating in the adiabatic case, and of an instability developing around the wake's stagnation point in the quasi-isothermal case. Moreover, at very high resolution, and Mach numbers above M_∞ ≥ 3, the flow behind the accretion bow shock becomes entirely dominated by these instabilities. As a result, accretion rates onto the black hole drop by about an order of magnitude in the adiabatic case, compared to the analytic BHL formula.

Obstacles to the Termination of Air Force Activities.

DTIC Science & Technology

1986-04-01

sugsts how. it the Air Force leadership con- eludes that termination is necessary the Air Force can surmount the obstacles.’ The stud v was cMIduct ed...the Air Force leadership concludes that the termination of a major activity is a promising or necessary management option, the report suggests that it...complicated inter- nal political process; it takes time to work out. The top leadership should begin the process of corporate strategy building and priority

Reducing the wave drag of wing airfoils in transonic flow regimes by the force action of airfoil surface elements on the flow

NASA Astrophysics Data System (ADS)

Aul'chenko, S. M.; Zamuraev, V. P.

2012-11-01

Mathematical modeling of the influence of forced oscillations of surface elements of a wing airfoil on the shock-wave structure of transonic flow past it has been carried out. The qualitative and quantitative influence of the oscillation parameters on the wave drag of the airfoil has been investigated.

Nanoscience and Technology at the Air Force Research Laboratory (AFRL)

DTIC Science & Technology

2005-05-01

AIR FORCE RESEARCH LABORATORY ( AFRL ) Dr. Richard A. Vaia Dr. Daniel Miracle Dr. Thomas Cruse Air Force Research ...Technology At The Air Force Research Laboratory ( AFRL ) 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT...98) Prescribed by ANSI Std Z39-18 AFRL NST Overview 2 AIR FORCE RESEARCH LABORATORY VISION We defend

Nanoscience and Technology at the Air Force Research Laboratory (AFRL)

DTIC Science & Technology

2005-02-01

AIR FORCE RESEARCH LABORATORY ( AFRL ) Dr. Richard A. Vaia Dr. Daniel Miracle Dr. Thomas Cruse Air Force Research ...Technology At The Air Force Research Laboratory ( AFRL ) 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT...98) Prescribed by ANSI Std Z39-18 AFRL NST Overview 2 AIR FORCE RESEARCH LABORATORY VISION We defend

Simplified Models for the Drag Coefficient of a Pitched Baseball

ERIC Educational Resources Information Center

Kagan, David; Nathan, Alan M.

2014-01-01

The classic experiment to measure the drag coefficient involves dropping coffee filters. Wouldn't it be more fun to try something different? In fact, an experiment on the drag force is conducted nearly 4000 times a day during the baseball season and you have free access to this PITCHf/x data!

Drag measurements on a laminar-flow body of revolution in the 13-inch magnetic suspension and balance system

NASA Technical Reports Server (NTRS)

Dress, David A.

1989-01-01

Low speed wind tunnel drag force measurements were taken on a laminar flow body of revolution free of support interference. This body was tested at zero incidence in the NASA Langley 13 in. Magnetic Suspension and Balance System (MSBS). The primary objective of these tests was to substantiate the drag force measuring capabilities of the 13 in. MSBS. The drag force calibrations and wind-on repeatability data provide a means of assessing these capabilities. Additional investigations include: (1) the effects of fixing transition; (2) the effects of fins installed in the tail; and (3) surface flow visualization using both liquid crystals and oil flow. Also two simple drag prediction codes were used to assess their usefulness in estimating overall body drag.

A Study on the Effects of J2 Perturbations on a Drag-Free Control System for Spacecraft in Low Earth Orbit

NASA Technical Reports Server (NTRS)

Vess, Melissa Fleck; Starin, Scott R.

2003-01-01

Low Earth Orbit (LEO) missions provide a unique means of gathering information about many of Earth s aspects such as climate, atmosphere, and gravitational field. Among the greatest challenges of LEO missions are designing, predicting, and maintaining the spacecraft orbit. The predominant perturbative forces acting on a spacecraft in LEO are J2 and higher order gravitational components, the effects of which are fairly easy to predict, and atmospheric drag, which causes the greatest uncertainty in predicting spacecraft ephemeris. The continuously varying atmospheric drag requires increased spacecraft tracking in order to accurately predict spacecraft location. In addition, periodic propulsive maneuvers typically must be planned and performed to counteract the effects of drag on the spacecraft orbit. If the effects of drag could be continuously and autonomously counteracted, the uncertainty in ephemeris due to atmospheric drag would essentially be eliminated from the spacecraft dynamics. One method of autonomous drag compensation that has been implemented on some missions is drag-free control. Drag-free control of a spacecraft was initially proposed in the 1960's and is discussed extensively by Lange. His drag-free control architecture consists of a free-floating proof mass enclosed within a spacecraft, isolating it from external disturbance forces such as atmospheric drag and solar radiation pressure. Under ideal conditions, internal disturbance forces can be ignored or mitigated, and the orbit of the proof mass depends only on gravitational forces. A sensor associated with the proof mass senses the movement of the spacecraft relative to the proof mass. Using the sensor measurements, the spacecraft is forced to follow the orbit of the proof mass by using low thrust propulsion, thus counteracting any non-gravitational disturbance forces. If the non-gravitational disturbance forces are successfully removed, the spacecraft s orbit will be affected only by well

Analysis of Organizational Architectures for the Air Force Tuition Assistance Program

DTIC Science & Technology

2003-03-01

FORCE TUITION ASSISTANCE PROGRAM THESIS Krista Zimmerman LaPietra AFIT/GOR/ENS/03-15 DEPARTMENT OF THE AIR FORCE AIR UNIVERSITY AIR...ANALYSIS OF ORGANIZATIONAL ARCHITECTURES FOR THE AIR FORCE TUITION ASSISTANCE PROGRAM THESIS Presented to the Faculty Department...ANALYSIS OF ORGANIZATIONAL ARCHITECTURES FOR THE AIR FORCE TUITION ASSISTANCE PROGRAM Krista Zimmerman LaPietra, BS

Starfleet Deferred: Project Orion in the 1962 Air Force Space Program

NASA Astrophysics Data System (ADS)

Ziarnick, B.

Project Orion, the Cold War American program (1957-1965) studying nuclear pulse propulsion for space applications, has long interested space enthusiasts for what it was and what it might have been, but it has long been believed that neither the United States government nor the US Air Force took the program very seriously. However, recently declassified US Air Force documents shed more light on the classified history of Project Orion. Far from being ignored by Air Force leadership, through the efforts of the Strategic Air Command, Air Force leaders like General Curtis LeMay were convinced that Project Orion should be funded as a major weapons system. The high water mark of Project Orion was the 1962 Air Force Space Program proposal by the Air Force Chief of Staff to devote almost twenty percent of the Air Force space budget from 1962-1967 to Orion development before the program was cancelled by the civilian Secretary of the Air Force under pressure from the Department of Defense. This paper details the history of Project Orion in the 1962 Air Force Space Program proposal, and concludes with a few lessons learned for use by modern interstellar advocates.

Promoting Sound Ethical Decisions in the Air Force: CGO Solutions to Air Force Moral and Ethical Lapses

DTIC Science & Technology

2014-07-01

The second step is to create a Cross Check program—essentially franchising the Think Tank process in smaller groups across the Air Force as a forum...accessed 20 July 2014). 32  Cross Check Think Tank 14D proposes the implementation of “Cross Check” programs—essentially franchising the Think Tank...Tank Franchise , the meetings would be action-oriented, and networked together throughout the Air Force to provide lessons-learned, 33  resources

Improving Energy Security for Air Force Installations

NASA Astrophysics Data System (ADS)

Schill, David

Like civilian infrastructure, Air Force installations are dependent on electrical energy for daily operations. Energy shortages translate to decreased productivity, higher costs, and increased health risks. But for the United States military, energy shortages have the potential to become national security risks. Over ninety-five percent of the electrical energy used by the Air Force is supplied by the domestic grid, which is susceptible to shortages and disruptions. Many Air Force operations require a continuous source of energy, and while the Air Force has historically established redundant supplies of electrical energy, these back-ups are designed for short-term outages and may not provide sufficient supply for a longer, sustained power outage. Furthermore, it is the goal of the Department of Defense to produce or procure 25 percent of its facility energy from renewable sources by fiscal year 2025. In a government budget environment where decision makers are required to provide more capability with less money, it is becoming increasingly important for informed decisions regarding which energy supply options bear the most benefit for an installation. The analysis begins by exploring the field of energy supply options available to an Air Force installation. The supply options are assessed according to their ability to provide continuous and reliable energy, their applicability to unique requirements of Air Force installations, and their costs. Various methods of calculating energy usage by an installation are also addressed. The next step of this research develops a methodology and tool which assesses how an installation responds to various power outage scenarios. Lastly, various energy supply options are applied to the tool, and the results are reported in terms of cost and loss of installation capability. This approach will allow installation commanders and energy managers the ability to evaluate the cost and effectiveness of various energy investment options.

Low-temperature forced-air drying of Appalachian hardwoods

Treesearch

Donald G. Cuppett; E. Paul Craft

1975-01-01

Low-temperature forced-air drying involves drying green lumber in heated buildings with forced-air circulation and partial control of temperature and humidity conditions. The lumber is dried to about 20 percent moisture content at dry-bulb temperatures of 70º to 110ºF and with air velocities of 300 to 600 feet per minute. Equipment, methods, and...

Air Force construction automation/robotics

NASA Technical Reports Server (NTRS)

Nease, AL; Dusseault, Christopher

1994-01-01

The Air Force has several unique requirements that are being met through the development of construction robotic technology. The missions associated with these requirements place construction/repair equipment operators in potentially harmful situations. Additionally, force reductions require that human resources be leveraged to the maximum extent possible and that more stringent construction repair requirements push for increased automation. To solve these problems, the U.S. Air Force is undertaking a research and development effort at Tyndall AFB, FL to develop robotic teleoperation, telerobotics, robotic vehicle communications, automated damage assessment, vehicle navigation, mission/vehicle task control architecture, and associated computing environment. The ultimate goal is the fielding of robotic repair capability operating at the level of supervised autonomy. The authors of this paper will discuss current and planned efforts in construction/repair, explosive ordnance disposal, hazardous waste cleanup, fire fighting, and space construction.

75 FR 32750 - US Air Force Scientific Advisory Board Notice of Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-09

... DEPARTMENT OF DEFENSE Department of the Air Force US Air Force Scientific Advisory Board Notice of Meeting AGENCY: Department of the Air Force, US Air Force Scientific Advisory Board. ACTION: Meeting....150, the Department of Defense announces that the United States Air Force Scientific Advisory Board...

An Experimental Investigation of Helicopter Rotor Hub Fairing Drag Characteristics

NASA Technical Reports Server (NTRS)

Sung, D. Y.; Lance, M. B.; Young, L. A.; Stroub, R. H.

1989-01-01

A study was done in the NASA 14- by 22-Foot Wind Tunnel at Langley Research Center on the parasite drag of different helicopter rotor hub fairings and pylons. Parametric studies of hub-fairing camber and diameter were conducted. The effect of hub fairing/pylon clearance on hub fairing/pylon mutual interference drag was examined in detail. Force and moment data are presented in tabular and graphical forms. The results indicate that hub fairings with a circular-arc upper surface and a flat lower surface yield maximum hub drag reduction; and clearance between the hub fairing and pylon induces high mutual-interference drag and diminishes the drag-reduction benefit obtained using a hub fairing with a flat lower surface. Test data show that symmetrical hub fairings with circular-arc surfaces generate 74 percent more interference drag than do cambered hub fairings with flat lower surfaces, at moderate negative angle of attack.

International Affairs Programs: The Air Force Versus the Army

DTIC Science & Technology

2015-10-01

individual tutoring programs . Additionally RAS personnel are offered regional enhancement studies opportunities at several facilities.48 RAS personnel...AU/ACSC/2015 AIR COMMAND AND STAFF COLLEGE AIR UNIVERSITY INTERNATIONAL AFFAIRS PROGRAMS : THE AIR FORCE VERSUS THE ARMY by Robin L...5 COMPARISON: INTERNATIONAL AFFAIRS PROGRAMS AIR FORCE VERSUS ARMY 8

United States Air Force Summer Research Program -- 1993. Volume 3. Phillips Laboratory

DTIC Science & Technology

1993-12-01

PHILLIPS LABORATORY KIRTLAND AIR FORCE BASE, NEW MEXICO SPONSORED BY: AIR FORCE OFFICE OF SCIENTIFIC RESEARCH ROLLING AIR FORCE BASE, WASHINGTON ,D.C...Report for. Summer Faculty Research Program at Phillips Laboratory Kirtland Air Force Base Sponsored by: Air Force Offlce of Scientific Research ...Prcgram Phillips Laboratory Kirtland

Drag measurements on a laminar flow body of revolution in Langley's 13 inch magnetic suspension and balance system. M.S. Thesis

NASA Technical Reports Server (NTRS)

Dress, David A.

1988-01-01

Low-speed wind tunnel drag force measurements were taken on a laminar flow body of revolution free of support interference. This body was tested at zero incidence in the NASA Langley 13 inch Magnetic Suspension and Balance System (MSBS). The primary objective of these tests was to substantiate the drag force measuring capabilities of the 13 inch MSBS. A secondary objective was to obtain support interference free drag measurements on an axisymmetric body of interest. Both objectives were met. The drag force calibrations and wind-on repeatability data provide a means of assessing the drag force measuring capabilities of the 13 inch MSBS. The measured drag coefficients for this body are of interest to researchers actively involved in designing minimum drag fuselage shapes. Additional investigations included: the effects of fixing transition; the effects of fins installed in the tail; surface flow visualizations using both liquid crystals and oil flow; and base pressure measurements using a one-channel telemetry system. Two drag prediction codes were used to assess their usefulness in estimating overall body drag. These theoretical results did not compare well with the measured values because of the following: incorrect or non-existent modeling of a laminar separation bubble on the body and incorrect of non-existent estimates of base pressure drag.

Environmental Assessment Proposed Demolition Plan Hill Air Force Base, Utah

DTIC Science & Technology

2010-04-01

1204, Arlington VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law , no person shall be subject to a penalty...Demolition Plan Hill Air Force Base, Utah 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR( S ) 5d. PROJECT NUMBER 5e. TASK...NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME( S ) AND ADDRESS(ES) United States Air Force - Air Force Material Command,Hill Air Force

Challenges of Enterprise Wide AM for Air Force Sustainment

DTIC Science & Technology

2016-12-01

December 2016 Naguy is chief of the Air Force Life Cycle Management Center’s Product Support Engineering Division at Wright Patterson Air Force Base in...today and into the future. To truly capitalize on the full potential of AM, the Air Force Life Cycle Management Center (AFLCMC) in close collabora...approach for material standards and quality include un- derstanding powder characteristics, developing an enterprise material characterization

Inspector General, DOD, Oversight of the Air Force Audit Agency Audit of the FY 1999 Air Force General Fund Financial Statements

DTIC Science & Technology

2000-02-14

Consolidated Financial Statements . Our objective was to determine the accuracy and completeness of the Air Force Audit Agency audit of the FY 1999 Air Force General Fund financial statements. See Appendix A for a discussion of the audit

An improved Cauchy number approach for predicting the drag and reconfiguration of flexible vegetation

NASA Astrophysics Data System (ADS)

Whittaker, Peter; Wilson, Catherine A. M. E.; Aberle, Jochen

2015-09-01

An improved model to describe the drag and reconfiguration of flexible riparian vegetation is proposed. The key improvement over previous models is the use of a refined 'vegetative' Cauchy number to explicitly determine the magnitude and rate of the vegetation's reconfiguration. After being derived from dimensional consideration, the model is applied to two experimental data sets. The first contains high-resolution drag force and physical property measurements for twenty-one foliated and defoliated full-scale trees, including specimens of Alnus glutinosa, Populus nigra and Salix alba. The second data set is independent and of a different scale, consisting of drag force and physical property measurements for natural and artificial branches of willow and poplar, under partially and fully submerged flow conditions. Good agreement between the measured and predicted drag forces is observed for both data sets, especially when compared to a more typical 'rigid' approximation, where the effects of reconfiguration are neglected.

Aerodynamic drag crisis and its possible effect on the flight of baseballs

NASA Astrophysics Data System (ADS)

Frohlich, Cliff

1984-04-01

At Reynolds numbers above about 105 the aerodynamic drag force on a sphere drops sharply as the flow begins to become turbulent in the boundary layer. For baseballs, this ``drag crisis'' may occur at speeds which are typical for pitched or batted balls. The effects of the drag reduction on the behavior of both pitched and batted balls is significant, and may explain several features of the game of baseball which previously have been unexplained or attributed to other causes. In particular, the drag reduction may help to explain why pitched fastballs appear to rise, why pitched curve balls appear to drop sharply, and why home run production has increased since the introduction of the alleged ``lively ball.'' Calculations suggest that aerodynamic forces are as important a factor in fastpitch softball as in baseball, and that they are a critical factor in a number of other ball games.

Embouchure Dysfunction in Air Force Band Brass Musicians.

PubMed

Storms, Patrick R; Elkins, Candice P; Strohecker, Eric M

2016-06-01

Occupational injuries and medical problems in musicians are well described, but relatively less attention has been paid to orofacial and embouchure-related problems in professional brass players. This study addressed embouchure-related problems in Air Force Band members, a population of musicians with an intense practice and performance schedule. A survey was developed and distributed via the Air Force Survey Office to 599 active-duty Air Force Band members and 201 Air National Guard members. The survey assessed practice patterns, practice and performance venues, and presence of symptoms suggesting embouchure dysfunction. Responses were obtained from 167 Air Force Band brass players. Of the 157 responding to the question about embouchure dysfunction, 42% reported having experienced an embouchure problem at some point in the past, and 53% of those respondents reported that they were currently experiencing an embouchure problem. Forty-one percent of those with embouchure problems cited practice venues that were not conducive to effective and efficient practice at the time their embouchure problems began, and 48% of those with embouchure problems reported having to overblow in rehearsal at the time their problems began. Embouchure disorders were reported in a large proportion of Air Force Band brass survey respondents, and specific concerns related to practice venues and the need to overblow in practice settings suggest factors suitable to remediation and preventive strategies.

Science and Technology: The Making of the Air Force Research Laboratory

DTIC Science & Technology

2000-01-01

AFRL . . . . . . . . . . . 187 11 Air Force Research Laboratory : Before and After...United States Air Force during my tenure as chief of staff—the crea - tion of the Air Force Research Laboratory ( AFRL ). As the “high technology” service...consolidate four existing laboratories into one Air Force Research Laboratory ( AFRL ) designed to lead to a more efficient and streamlined

Is drag luminosity effective in recurrent novae

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kato, Mariko; Hachisu, Izumi

1991-06-01

A study has been made of the efficiency of frictional processes in common envelope phase at outbursts of three recurrent novae T Pyx, U Sco, and RS Oph, by using steady-state wind models. The drag luminosity is found to depend strongly on the envelope mass. It may play an important role for a relatively massive envelope of about 0.0001 solar mass or more. For recurrent novae, however, acceleration due to the drag force is not important to eject the envelope mass because of its small envelope mass. Since the drag luminosity can be neglected at the extended phase of novamore » outburst, the light curves of these recurrent novae are determined only by the wind-driven mass loss as shown by Kato (1990). 23 refs.« less

U.S. Air Force Annual Financial Statement 2010

DTIC Science & Technology

2010-01-01

certain contract financing payments that are not reported elsewhere on Air Force’s Balance Sheet. The Air Force conducts business with commercial...the reporting entity has a contractual commitment for payment is $712.8 million. The Air Force is a party in numerous individual contracts that...promulgated by the Federal Accounting Standards Advisory Board; the Office of Management and Budget (OMB) Circular No. A-136, Financial Reporting

Assessment of dual-point drag reduction for an executive-jet modified airfoil section

NASA Technical Reports Server (NTRS)

Allison, Dennis O.; Mineck, Raymond E.

1996-01-01

This paper presents aerodynamic characteristics and pressure distributions for an executive-jet modified airfoil and discusses drag reduction relative to a baseline airfoil for two cruise design points. A modified airfoil was tested in the adaptive-wall test section of the NASA Langley 0.3-Meter Transonic Cryogenic Tunnel (0.3-m TCT) for Mach numbers ranging from 0.250 to 0.780 and chord Reynolds numbers ranging from 3.0 x 10(exp 6) to 18.0 x 10(exp 6). The angle of attack was varied from minus 2 degrees to almost 10 degrees. Boundary-layer transition was fixed at 5 percent of chord on both the upper and lower surfaces of the model for most of the test. The two design Mach numbers were 0.654 and 0.735, chord Reynolds numbers were 4.5 x 10(exp 6) and 8.9 x 10(exp 6), and normal-force coefficients were 0.98 and 0.51. Test data are presented graphically as integrated force and moment coefficients and chordwise pressure distributions. The maximum normal-force coefficient decreases with increasing Mach number. At a constant normal-force coefficient in the linear region, as Mach number increases an increase occurs in the slope of normal-force coefficient versus angle of attack, negative pitching-moment coefficient, and drag coefficient. With increasing Reynolds number at a constant normal-force coefficient, the pitching-moment coefficient becomes more negative and the drag coefficient decreases. The pressure distributions reveal that when present, separation begins at the trailing edge as angle of attack is increased. The modified airfoil, which is designed with pitching moment and geometric constraints relative to the baseline airfoil, achieved drag reductions for both design points (12 and 22 counts). The drag reductions are associated with stronger suction pressures in the first 10 percent of the upper surface and weakened shock waves.

Army and Air Force Unmanned Air Reconnaissance: Warrior and Hydra Navigating a Maze of Strategic Hedges

DTIC Science & Technology

2009-06-01

Chambliss; Colonel Michael Stickney; Colonel Eric Mathewson; Lieutenant Colonel Robert Kiebler; Lieutenant Colonel Kenneth Kilmurray; Lieutenant...16 Peter Layton , Group Captain, Royal Air Force, “Hedging Strategies, UCAVs, budgets, and improbable threats,” Armed Forces Journal...10 Colonel Eric Mathewson, US Air Force HAF/A2 DCS ISR, “Air Force ISR in a Changed World: ISR Transformation, the Importance

Drag Reduction On Multiscale Superhydrophobic Surfaces

NASA Astrophysics Data System (ADS)

Jenner, Elliot; Barbier, Charlotte; D'Urso, Brian

2013-11-01

Fluid drag reduction is of great interest in a variety of fields, including hull engineering, microfluidics, and drug delivery. We fabricated samples with multi-scale superhydrophobic surfaces, which consist of hexagonally self-ordered microscopic spikes grown via anodization on macroscopic grooves cut in aluminum. The hydrodynamic drag properties were studied with a cone-and-plate rheometer, showing significant drag reduction near 15% in turbulent flow and near 30% in laminar flow. In addition to these experiments, numerical simulations were performed in order to estimate the slip length at high speeds. Furthermore, we will report on the progress of experiments with a new type of surface combining superhydrophobic surfaces like those discussed above with Slippery Liquid Infused Porous Surfaces (SLIPS), which utilize an oil layer to create a hydrophobic self-repairing surface. These ``Super-SLIPS'' may combine the best properties of both superhydrophobic surfaces and SLIPS, by combining a drag reducing air-layer and an oil layer which may improve durability and biofouling resistance. This research was supported by the ORNL Seed Money Program. Oak Ridge National Laboratory is managed by UT-Battelle, LLC, for the U.S. Dept. of Energy under contract DE-AC05-00OR22725.

United States Air Force Summer Research Program -- 1993. Volume 13. Phillips Laboratory

DTIC Science & Technology

1993-12-01

Research Kirtland Air Force Base, Albuquerque, NM August 1993 14-1 My Summer Apprenticeship At Kirtland Air Force Base, Phillips Laboratory Andrea Garcia...AFOSR Summer Research Program Phillips Laboratory Sponsored By: Air Force Office of Scientific Research Kirtland Air Force Base, Albuquerque, NM... Phillips Laboratory Sponsored by: Air

An analytic method to account for drag in the Vinti Satellite theory

NASA Technical Reports Server (NTRS)

Watson, J. S.; Mistretta, G. D.; Bonavito, N. L.

1974-01-01

To retain separability in the Vinti theory of earth satellite motion when a nonconservative force such as air drag is considered, a set of variational equations for the orbital elements are introduced, and expressed as functions of the transverse, radial, and normal components of the nonconservative forces acting on the system. In this approach, the Hamiltonian is preserved in form, and remains the total energy, but the initial or boundary conditions and hence the Jacobi constants of the motion advance with time through the variational equations. In particular, the atmospheric density profile is written as a fitted exponential function of the eccentric anomaly, which adheres to tabular data at all altitudes and simultaneously reduced the variational equations to indefinite integrals with closed form evaluations. The values of the limits for any arbitrary time interval are obtained from the Vinti program.

Evaluation of Air Force and Navy Demand Forecasting Systems

DTIC Science & Technology

1994-01-01

forecasting approach, the Air Force Material Command is questioning the adoption of the Navy’s Statistical Demand Forecasting System ( Gitman , 1994). The...Recoverable Item Process in the Requirements Data Bank System is to manage reparable spare parts ( Gitman , 1994). Although RDB will have the capability of...D062) ( Gitman , 1994). Since a comparison is made to address Air Force concerns, this research only limits its analysis to the range of Air Force

Reducing drag of a commuter train, using engine exhaust momentum

NASA Astrophysics Data System (ADS)

Ha, Dong Keun

The objective of this thesis was to perform numerical investigations of two different methods of injecting fluid momentum into the air flow above a commuter train to reduce its drag. Based on previous aerodynamic modifications of heavy duty trucks in improving fuel efficiency, two structural modifications were designed and applied to a Metrolink Services commuter train in the Los Angeles (LA) County area to reduce its drag and subsequently improve fuel efficiency. The first modification was an L-shaped channel, added to the exhaust cooling fan above the locomotive roof to divert and align the exhaust gases in the axial direction. The second modification was adding an airfoil shaped lid over the L-shape channel, to minimize the drag of the perturbed structure, and thus reduce the overall drag. The computational fluid dynamic (CFD) software CCM+ from CD-Adapco with the ?-? turbulence model was used for the simulations. A single train set which consists of three vehicles: one locomotive, one trailer car and one cab car were used. All the vehicles were modeled based on the standard Metrolink fleet train size. The wind speed was at 90 miles per hour (mph), which is the maximum speed for the Orange County Metrolink line. Air was used as the exhaust gas in the simulation. The temperature of the exhausting air emitting out of the cooling fan on the roof was 150 F and the average fan speed was 120 mph. Results showed that with the addition of the lid, momentum injection results in reduced flow separation and pressure recovery behind the locomotive, which reduces the overall drag by at least 30%.

U.S. Air Force Environmental Assessment, Steam Decentralization Project, Tinker Air Force Base, Oklahoma

DTIC Science & Technology

2011-08-01

Estimated Air Pollutant Emissions for Boilers at CSPs at Tinker AFB ..................... 3-8 6 Table 3-2. Special Status Plant and Animal Species of...environment associated with the decentralization and optimization offour central steam plants (CSPs) located at Tinker Air Force Base (AFB), Oklahoma...square feet and represent approximately 48 percent of the installation’s total building area. Three of the plants (CSP 208, CSP 3001 and CSP 5802

Surgically Shaping a Financial Hydra: Reprogramming United States Air Force End Strength to the Air Reserve Component

DTIC Science & Technology

2012-02-14

Director of the Air National Guard20 Lt Gen Charles E. Stenner Jr., Chief of the Air Force Reserve21 Specificity about what rebalancing the force...January 2012). Sharp, Travis. Vision Meets Reality: 2010 QDR and 2011 Defense Budget. Center for a New American Security, February 2010. Stenner ...Lt Gen Charles E. Stenner Jr., commander of Air Force Reserve Command (address, Air Force Reserve Senior Leader Conference

Effect of flow oscillations on cavity drag and a technique for their control

NASA Technical Reports Server (NTRS)

Gharib, M.; Roshko, A.; Sarohia, V.

1985-01-01

Experiments to relate the state of the shear layer to cavity drag have been performed in a water channel using a 4" axisymmetric cavity model. Detailed flow measurements in various cavity flow oscillation phases, amplitude amplification along the flow direction, distribution of shear stress, and other momentum flux obtained by laser Doppler velocimeter are presented. Measurements show exponential dependence of cavity drag on the length of the cavity. A jump in the cavity drag coefficient is observed as the cavity flow shows a bluff body wake type behavior. Natural and forced oscillations are introduced by a sinusoidally heated thin-film strip which excites the Tollmein-Schlichting waves in the boundary layer upstream of the gap. For a large gap, self-sustained periodic oscillations are observed, while for smaller gaps, which do not oscillate naturally, periodical oscillations can be obtained by external forcing through the strip heater. The drag of the cavity can be increased by one order of magnitude in the non-oscillating case through external forcing. Also, it is possible to completely eliminate mode switching by external forcing. For the first time, it is demonstrated that amplitude of cavity flow Kelvin-Helmholtz wave is dampened or cancelled by introduction of external perturbation of natural flow frequency but different phase.

Air Force Leadership Development: Transformation’s Constant

DTIC Science & Technology

2003-05-01

AU/SCHOOL/NNN/2001-04 DEPARTMENT OF STATE SENIOR SEMINAR NATIONAL FOREIGN AFFAIRS TRAINING CENTER AIR FORCE LEADERSHIP DEVELOPMENT...valid OMB control number. 1. REPORT DATE MAY 2003 2. REPORT TYPE N/A 3. DATES COVERED - 4. TITLE AND SUBTITLE Air Force Leadership ...6 THE LEADERSHIP ESSENTIALS

Preliminary Investigation in the NACA Low-Turbulence Tunnel of Low-drag Airfoil Sections Suitable for Admitting Air at the Leading Edge

NASA Technical Reports Server (NTRS)

von Doenhoff, Albert E.; Horton, Elmer A.

1942-01-01

An investigation was carried out in the NACA low-turbulence tunnel to develop low-drag airfoil sections suitable for admitting air at the leading edge. A thickness distribution having the desired type of pressure distribution was found from tests of a flexible model. Other airfoil shapes were derived from this original shape by varying the thickness, the camper, the leading-edge radius, and the size of the leading-edge opening. Data are presented giving the characteristics of the airfoil shapes in the range of lift coefficients for high-speed and cruising flight. Shapes have been developed which show no substantial increases in drag over that of the same position along the chord. Many of these shapes appear to have higher critical compressibility speeds than plain airfoils of the same thickness. Low-drag airfoil sections have been developed with openings in the leading edge as large as 41.5 percent of the maximum thickness. The range of lift coefficients for low drag in several cases is nearly as large as that of the corresponding plain airfoil sections. Preliminary measurements of maximum lift characteristics indicate that nose-opening sections of the type herein considered may not produce any marked effects on the maximum lift coefficient.

Environmental Assessment: Military Family Housing Privatization Maxwell Air Force Base

DTIC Science & Technology

2005-06-01

Ray L. Raton Mildred J . Worthy February 9, 2005 Lt. Colonel David W. Maninez Deputy Commander, 42nd MSG 50 South LeMay Plaza (Bldg 804) Maxwell ...Environmental Assessment Military Family Housing Privatization Maxwell Air Force Base United States Air Force Air Education and Training Command... Maxwell Air Force Base, Alabama June 2005 Report Documentation Page Form ApprovedOMB No. 0704-0188 Public reporting burden for the collection of

32 CFR 644.327 - Air Force military real property.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 32 National Defense 4 2010-07-01 2010-07-01 true Air Force military real property. 644.327 Section... Force military real property. Military real property under the control of the Department of the Air Force will be placed in excess status as outlined in AFR 87-4. ...

32 CFR 806.29 - Administrative processing of Air Force FOIA requests.

Code of Federal Regulations, 2012 CFR

2012-07-01

... section. (c) Contacts with FOIA requesters and non-Air Force submitters of data. (1) Contacts with Air... memoranda documenting requester contacts with Air Force elements regarding a pending FOIA request in the requester's FOIA file. If the requester contacts Air Force elements telephonically about a pending FOIA...

32 CFR 806.29 - Administrative processing of Air Force FOIA requests.

Code of Federal Regulations, 2011 CFR

2011-07-01

... section. (c) Contacts with FOIA requesters and non-Air Force submitters of data. (1) Contacts with Air... memoranda documenting requester contacts with Air Force elements regarding a pending FOIA request in the requester's FOIA file. If the requester contacts Air Force elements telephonically about a pending FOIA...

32 CFR 806.29 - Administrative processing of Air Force FOIA requests.

Code of Federal Regulations, 2014 CFR

2014-07-01

... section. (c) Contacts with FOIA requesters and non-Air Force submitters of data. (1) Contacts with Air... memoranda documenting requester contacts with Air Force elements regarding a pending FOIA request in the requester's FOIA file. If the requester contacts Air Force elements telephonically about a pending FOIA...

Simultaneous drag and flow measurements of Olympic skeleton athletes

NASA Astrophysics Data System (ADS)

Moon, Yae Eun; Digiulio, David; Peters, Steve; Wei, Timothy

2009-11-01

The Olympic sport of skeleton involves an athlete riding a small sled face first down a bobsled track at speeds up to 130 km/hr. In these races, the difference between gold and missing the medal stand altogether can be hundredths of a second per run. As such, reducing aerodynamic drag through proper body positioning is of first order importance. To better study the flow behavior and to improve the performance of the athletes, we constructed a static force balance system on a mock section of a bobsled track. Athlete and the sled are placed on the force balance system which is positioned at the exit of an open loop wind tunnel. Simultaneous drag force and DPIV velocity field measurements were made along with video recordings of body position to aid the athletes in determining their optimal aerodynamic body position.

Absenteeism Among Air Force Active Duty and Civilian Personnel.

DTIC Science & Technology

1985-09-01

Fitzgibbons, Dale and Michael Moch. "Employee Absenteeism : A Multivariate Analysis with Replication," Organizational Behavior and Human Performance ...AD-A161 073 ABSENTEEISM AMONG AIR FORCE ACTIVE DUTY AND CIVILIAN PERSONNEL(U) AIR FORCE INST OF TECH IRIGHT-PRTTERSON AFB OH SCHOOL OF SYSTEMS AND...8217o 7 ABSENTEEISM AMONG AIR FORCE ACTIUE DUTY AND CIUILIAN PERSONNEL THESIS William M. Getter Captain, USAF AF IT/GLM/LSB/5S-27 DT|C ELECTE SNOVI 2Q8 v

SOUTHEAST AND NORTHEAST SIDES. Looking west Edwards Air Force ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

SOUTHEAST AND NORTHEAST SIDES. Looking west - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Fuel & Water Tank, Test Area 1-115, northwest end of Saturn Boulevard, Boron, Kern County, CA

2. GENERAL VIEW OF SLC3 AIR FORCE BUILDING (BLDG. 761) ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

2. GENERAL VIEW OF SLC-3 AIR FORCE BUILDING (BLDG. 761) FROM THE NORTHWEST - Vandenberg Air Force Base, Space Launch Complex 3, SLC-3 Air Force Building, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

1. GENERAL VIEW OF SLC3 AIR FORCE BUILDING (BLDG. 761) ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

1. GENERAL VIEW OF SLC-3 AIR FORCE BUILDING (BLDG. 761) FROM THE SOUTHWEST - Vandenberg Air Force Base, Space Launch Complex 3, SLC-3 Air Force Building, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

Hazardous waste: Siting of storage facility at Kelly Air Force Base, Texas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1987-01-01

This report provides information on whether the hazardous waste storage facility at Kelly Air Force Base meets Resource Conservation and Recovery Act, state, and Air Force siting requirements; on whether the Air Force or the Defense Reutilization and Marketing Office selected the best site available to protect the public and to preserve good public relations with the community; on whether the Air Force, Kelly Air Force Base, or the Defense Logistics Agency adjusted siting standards as a result of the adverse publicity the hazardous waste facility has generated; and on whether Kelly Air Force Base is revising its hazardous wastemore » management organization so that it is similar to the organizations at Tinker and McClellan Air Force Bases.« less

Method to estimate drag coefficient at the air/ice interface over drifting open pack ice from remotely sensed data

NASA Technical Reports Server (NTRS)

Feldman, U.

1984-01-01

A knowledge in near real time, of the surface drag coefficient for drifting pack ice is vital for predicting its motions. And since this is not routinely available from measurements it must be replaced by estimates. Hence, a method for estimating this variable, as well as the drag coefficient at the water/ice interface and the ice thickness, for drifting open pack ice was developed. These estimates were derived from three-day sequences of LANDSAT-1 MSS images and surface weather charts and from the observed minima and maxima of these variables. The method was tested with four data sets in the southeastern Beaufort sea. Acceptable results were obtained for three data sets. Routine application of the method depends on the availability of data from an all-weather air or spaceborne remote sensing system, producing images with high geometric fidelity and high resolution.

Air Force Research Laboratory Sensors Directorate Leadership Legacy, 1960-2011

DTIC Science & Technology

2011-03-01

AFRL -RY-WP-TM-2011-1017 AIR FORCE RESEARCH LABORATORY SENSORS DIRECTORATE LEADERSHIP LEGACY, 1960-2011 Compiled by Raymond C. Rang...Structures Divi- sion, Space Vehicles Directorate, Air Force Research Laboratory , Kirtland AFB, N.M. 7. March 1998 - July 1999, Chief, Integration and... Research Laboratory ( AFRL ), and Deputy Director of the Sensors Direc- torate, Air Force Research

10. "TEST STAND 15, AIR FORCE FLIGHT TEST CENTER." ca. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

10. "TEST STAND 1-5, AIR FORCE FLIGHT TEST CENTER." ca. 1958. Test Area 1-115. Original is a color print, showing Test Stand 1-5 from below, also showing the superstructure of TS1-4 at left. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Leuhman Ridge near Highways 58 & 395, Boron, Kern County, CA

76 FR 18537 - U.S. Air Force Scientific Advisory Board; Notice of Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2011-04-04

... DEPARTMENT OF DEFENSE Department of the Air Force U.S. Air Force Scientific Advisory Board; Notice of Meeting AGENCY: Department of the Air Force, US Air Force Scientific Advisory Board. ACTION... 102-3.150, the Department of Defense announces that the United States Air Force Scientific Advisory...

INTEGRATION OF PARTICLE-GAS SYSTEMS WITH STIFF MUTUAL DRAG INTERACTION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Chao-Chin; Johansen, Anders, E-mail: ccyang@astro.lu.se, E-mail: anders@astro.lu.se

2016-06-01

Numerical simulation of numerous mm/cm-sized particles embedded in a gaseous disk has become an important tool in the study of planet formation and in understanding the dust distribution in observed protoplanetary disks. However, the mutual drag force between the gas and the particles can become so stiff—particularly because of small particles and/or strong local solid concentration—that an explicit integration of this system is computationally formidable. In this work, we consider the integration of the mutual drag force in a system of Eulerian gas and Lagrangian solid particles. Despite the entanglement between the gas and the particles under the particle-mesh construct,more » we are able to devise a numerical algorithm that effectively decomposes the globally coupled system of equations for the mutual drag force, and makes it possible to integrate this system on a cell-by-cell basis, which considerably reduces the computational task required. We use an analytical solution for the temporal evolution of each cell to relieve the time-step constraint posed by the mutual drag force, as well as to achieve the highest degree of accuracy. To validate our algorithm, we use an extensive suite of benchmarks with known solutions in one, two, and three dimensions, including the linear growth and the nonlinear saturation of the streaming instability. We demonstrate numerical convergence and satisfactory consistency in all cases. Our algorithm can, for example, be applied to model the evolution of the streaming instability with mm/cm-sized pebbles at high mass loading, which has important consequences for the formation scenarios of planetesimals.« less

The United States Air Force in Korea: A Chronology, 1950-1953

DTIC Science & Technology

2000-01-01

War , the U.S. Air Force (USAF) Historian commissioned the Research Division, Air Force His- torical Research Agency (AFHRA), Maxwell Air Force Base...and aces. Finally, it attempts to summarize those USAF events in Korea that best illustrate the air war and the application of air power in the...sources, usually to confirm the most signifi- cant events of the air war in Korea. AFHRA historians or archivists who researched and wrote the monthly and

Forced convection heat transfer to air/water vapor mixtures

NASA Technical Reports Server (NTRS)

Richards, D. R.; Florschuetz, L. W.

1984-01-01

Heat transfer coefficients were measured using both dry and humid air in the same forced convection cooling scheme and were compared using appropriate nondimensional parameters (Nusselt, Prandtl and Reynolds numbers). A forced convection scheme with a complex flow field, two dimensional arrays of circular jets with crossflow, was utilized with humidity ratios (mass ratio of water vapor to air) up to 0.23. The dynamic viscosity, thermal conductivity and specific heat of air, steam and air/steam mixtures are examined. Methods for determining gaseous mixture properties from the properties of their pure components are reviewed as well as methods for determining these properties with good confidence. The need for more experimentally determined property data for humid air is discussed. It is concluded that dimensionless forms of forced convection heat transfer data and empirical correlations based on measurements with dry air may be applied to conditions involving humid air with the same confidence as for the dry air case itself, provided that the thermophysical properties of the humid air mixtures are known with the same confidence as their dry air counterparts.

76 FR 65187 - U.S. Air Force Scientific Advisory Board Notice of Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2011-10-20

... DEPARTMENT OF DEFENSE Department of the Air Force U.S. Air Force Scientific Advisory Board Notice of Meeting AGENCY: US Air Force Scientific Advisory Board, Department of the Air Force, DoD. ACTION: Meeting Cancellation Notice. SUMMARY: Due to difficulties, beyond the control of the U.S. Air Force...

Air Force Journal of Logistics. Volume 29, Number 1, Spring 2005

DTIC Science & Technology

2005-01-01

Air Force, is necessary in the transaction of the public business as required by the law of the department. The Secretary of the Air Force approved the...reengineer Air Force Materiel Command (AFMC) progress and introduce a supplier scorecard. sustainment business processes. This transformation effort, AFMC...empowerment." company. I think one of the things we’re seeing in American However, the business side of the Air Force consistently has business is a resurgence

4. BUILDING 8767, INTERIOR. Looking west. Edwards Air Force ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

4. BUILDING 8767, INTERIOR. Looking west. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Observation Bunkers for Test Stand 1-A, Test Area 1-120, north end of Jupiter Boulevard, Boron, Kern County, CA

Drag of a Cottrell atmosphere by an edge dislocation in a smectic-A liquid crystal.

PubMed

Oswald, P; Lejček, L

2017-10-01

In a recent letter (P. Oswald et al., EPL 103, 46004 (2013)), we have shown that a smectic-A phase hardens in compression normal to the layers when the liquid crystal is doped with gold nanoparticles. This is due to the formation of Cottrell clouds nearby the core of the edge dislocations and the appearance of an additional drag force that reduces their mobility. We theoretically calculate the shape of the Cottrell cloud and the associated drag force as a function of the climb velocity of the dislocations. The main result is that the drag force depends on velocity and vanishes when the temperature tends to the smectic-A-to-nematic transition temperature. The role of the diffusion anisotropy is also evaluated.

Fixing the Mobility Air Forces New Way

DTIC Science & Technology

2013-03-01

Stenner explains, “Our units and people make outstanding contributions to the national defense. Every day, we leverage a portion of the strategic...calculate the ARC’s contribution to the military’s global reach.78 The cost effectiveness that General Stenner refers to is only one of at least three...Department of the Air Force, Mobilization Planning, 18. 60 Ibid. 61 U.S. Department of the Air Force, Mobilization Planning, 9. 62 Charles E. Stenner

76 FR 28215 - U.S. Air Force Scientific Advisory Board Notice of Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2011-05-16

... DEPARTMENT OF DEFENSE Department of the Air Force U.S. Air Force Scientific Advisory Board Notice of Meeting AGENCY: Department of the Air Force, U.S. Air Force Scientific Advisory Board, DoD. ACTION... 102-3.150, the Department of Defense announces that the United States Air Force Scientific Advisory...

Air Force Officer Specialty Structure. Reviewing the Fundamentals

DTIC Science & Technology

2009-01-01

Corporation, is the U.S. Air Force’s federally funded research and development center for studies and analyses. PAF pro - vides the Air Force with...Shirlene LeBleu for sharing their database and insights about job con - tent and specialty analyses. At the Air Force Manpower Agency, we thank Col...processes. Also, we thank Maj Ernest Wearren (AF/ A1MZ) and Gary Stockinger (AF/A1MX) for sharing their knowledge of the Manpower Pro - gramming Execution

Air Force Health Study. An Epidemiologic Investigation of Health Effects in Air Force Personnel Following Exposure to Herbicides. Volume 1

DTIC Science & Technology

1991-03-01

found to be significantly associated with coordination and a central nervous system index, but cranial nerve function and peripheral nerve status...AD-A237 516 Air Force Health Study A An Epidemiologic In vestigation of Health Effects in Air Force Personnel Following Exposure to Herbicides SAIC...Smeda SCIENCE APPLICATIONS EPIDEMIOLOGY RESEARCH DIVISION INTERNATIONAL CORPORATION ARMSTRONG LABORATORY 8400 Westpark Drive HUMAN SYSTEMS DIVISION

77 FR 22770 - U.S. Air Force Scientific Advisory Board; Notice of Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2012-04-17

... extended use of Air Force Space Command space-based sensors. In accordance with 5 U.S.C. 552b, as amended... DEPARTMENT OF DEFENSE Department of the Air Force U.S. Air Force Scientific Advisory Board; Notice of Meeting AGENCY: Department of the Air Force, U.S. Air Force Scientific Advisory Board. ACTION...

Drag of Clean and Fouled Net Panels – Measurements and Parameterization of Fouling

PubMed Central

Gansel, Lars Christian; Plew, David R.; Endresen, Per Christian; Olsen, Anna Ivanova; Misimi, Ekrem; Guenther, Jana; Jensen, Østen

2015-01-01

Biofouling is a serious problem in marine aquaculture and it has a number of negative impacts including increased forces on aquaculture structures and reduced water exchange across nets. This in turn affects the behavior of fish cages in waves and currents and has an impact on the water volume and quality inside net pens. Even though these negative effects are acknowledged by the research community and governmental institutions, there is limited knowledge about fouling related effects on the flow past nets, and more detailed investigations distinguishing between different fouling types have been called for. This study evaluates the effect of hydroids, an important fouling organism in Norwegian aquaculture, on the forces acting on net panels. Drag forces on clean and fouled nets were measured in a flume tank, and net solidity including effect of fouling were determined using image analysis. The relationship between net solidity and drag was assessed, and it was found that a solidity increase due to hydroids caused less additional drag than a similar increase caused by change in clean net parameters. For solidities tested in this study, the difference in drag force increase could be as high as 43% between fouled and clean nets with same solidity. The relationship between solidity and drag force is well described by exponential functions for clean as well as for fouled nets. A method is proposed to parameterize the effect of fouling in terms of an increase in net solidity. This allows existing numerical methods developed for clean nets to be used to model the effects of biofouling on nets. Measurements with other types of fouling can be added to build a database on effects of the accumulation of different fouling organisms on aquaculture nets. PMID:26151907

United States Air Force Graduate Student Research Program. 1989 Program Management Report

DTIC Science & Technology

1989-12-01

research at Air Force laboratories /centers. Each assignment is in a subject area and at an Air Force facility mutually agreed upon by the...housing difficult to find, c) 10 weeks too short for research period. June 20, 1989 Astronautics Laboratory Edwards Air Force Base, California June 21...1989 HRL: Operations Training Division Williams Air Force Base, Arizona June 22, 1989 Weapons Laboratory Kirtland Air

Atmospheric drag model calibrations for spacecraft lifetime prediction

NASA Technical Reports Server (NTRS)

Binebrink, A. L.; Radomski, M. S.; Samii, M. V.

1989-01-01

Although solar activity prediction uncertainty normally dominates decay prediction error budget for near-Earth spacecraft, the effect of drag force modeling errors for given levels of solar activity needs to be considered. Two atmospheric density models, the modified Harris-Priester model and the Jacchia-Roberts model, to reproduce the decay histories of the Solar Mesosphere Explorer (SME) and Solar Maximum Mission (SMM) spacecraft in the 490- to 540-kilometer altitude range were analyzed. Historical solar activity data were used in the input to the density computations. For each spacecraft and atmospheric model, a drag scaling adjustment factor was determined for a high-solar-activity year, such that the observed annual decay in the mean semimajor axis was reproduced by an averaged variation-of-parameters (VOP) orbit propagation. The SME (SMM) calibration was performed using calendar year 1983 (1982). The resulting calibration factors differ by 20 to 40 percent from the predictions of the prelaunch ballistic coefficients. The orbit propagations for each spacecraft were extended to the middle of 1988 using the calibrated drag models. For the Jaccia-Roberts density model, the observed decay in the mean semimajor axis of SME (SMM) over the 4.5-year (5.5-year) predictive period was reproduced to within 1.5 (4.4) percent. The corresponding figure for the Harris-Priester model was 8.6 (20.6) percent. Detailed results and conclusions regarding the importance of accurate drag force modeling for lifetime predictions are presented.

Mindfulness over matter > U.S. Air Force > Article Display

Science.gov Websites

Speeches Archive Former AF Top 3 Viewpoints and Speeches Air Force Warrior Games 2017 Events 2018 Air Force Strategic Documents Desert Storm 25th Anniversary Observances DoD Warrior Games Portraits in Courage

Report on Operations of the Air Force Geophysics Laboratory Infrared Array Spectrometer

DTIC Science & Technology

1993-01-25

AIR FORCE GEOPHYSICS LABORATORY INFRARED ARRAY... LABORATORY Directorate of Geophysics AIR FORCE MATERIEL COMMAND HANSCOM AIR FORCE BASE, MA 01731-3010 93-27655IEEE|EIIE1ENI This technical report has...ACKNOWLEDGMENT We are grateful to the Air Force Office of Scientific Research , especially Henry Radowski. for their financial corn- mitment to this project.

The Official Home Page of the U.S. Air Force

Science.gov Websites

: May 24 Air Force directs one-day operational safety review SecAF LOI SecAF LOI Letter of Intent AF and members using two C-130 and one C-17 training airframes. (U.S. Air Force photo by Richard Eldridge) The Transport Team crew members using two C-130 and one C-17 training airframes. (U.S. Air Force photo by

Air Force construction automation/robotics

NASA Technical Reports Server (NTRS)

Nease, A. D.; Alexander, E. F.

1993-01-01

The Air Force has several missions which generate unique requirements that are being met through the development of construction robotic technology. One especially important mission will be the conduct of Department of Defense (DOD) space activities. Space operations and other missions place construction/repair equipment operators in dangerous environments and potentially harmful situations. Additionally, force reductions require that human resources be leveraged to the maximum extent possible, and more stringent construction repair requirements push for increased automation. To solve these problems, the U.S. Air Force is undertaking a research and development effort at Tyndall AFB, FL, to develop robotic construction/repair equipment. This development effort involves the following technologies: teleoperation, telerobotics, construction operations (excavation, grading, leveling, tool change), robotic vehicle communications, vehicle navigation, mission/vehicle task control architecture, and associated computing environment. The ultimate goal is the fielding of a robotic repair capability operating at the level of supervised autonomy. This paper will discuss current and planned efforts in space construction/repair, explosive ordnance disposal, hazardous waste cleanup, and fire fighting.

77 FR 5781 - Record of Decision for the Air Space Training Initiative Shaw Air Force Base, South Carolina...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-06

... DEPARTMENT OF DEFENSE Department of the Air Force Record of Decision for the Air Space Training Initiative Shaw Air Force Base, South Carolina Final Environmental Impact Statement ACTION: Notice of Availability (NOA) of a Record of Decision (ROD). SUMMARY: On December 9, 2011, the United States Air Force...

Creating Joint Leaders Today for a Successful Air Force Tomorrow (1REV)

DTIC Science & Technology

2016-04-01

armed force in the same grade and competitive category who are serving on, or have served on, the HQ staff of their armed force; and 2. Officers in the...period from the release of the promotion results and the pin-on date. 5 Department of the Air Force, HQ Air Force Personnel Center, Demographics and...2009), Section 619a. 9 ibid, Section 619a. 10 Department of the Air Force, HQ Air Force Personnel Center, A-1 Manpower Division. 11 Phone

The United States Air Force Academy: A Bibliography 1954 - 1964

DTIC Science & Technology

1966-01-01

August 1958. 498 Stringer, Roger. " Pro Nobis Astra" (Class of 󈨁 selects its ring), Talon 5;5, May 1960. 499 Trotogott, Pete. Cadet...relate to establishing an air academy. These are not included since they have no specific bearing on the Academy as it now exists. The Library staff...Newsletter AF Times - Air Force Times Air Cond Heat & Ven - Air Conditioning, Heating, and Venti- lating Air Force Airman Air Power Historian

Calculated Drag of an Aerial Refueling Assembly Through Airplane Performance Analysis

NASA Technical Reports Server (NTRS)

Vachon, Michael Jacob; Ray, Ronald J.

2004-01-01

The aerodynamic drag of an aerial refueling assembly was calculated during the Automated Aerial Refueling project at the NASA Dryden Flight Research Center. An F/A-18A airplane was specially instrumented to obtain accurate fuel flow measurements and to determine engine thrust. A standard Navy air refueling store with a retractable refueling hose and paradrogue was mounted to the centerline pylon of the F/A-18A airplane. As the paradrogue assembly was deployed and stowed, changes in the calculated thrust of the airplane occurred and were equated to changes in vehicle drag. These drag changes were attributable to the drag of the paradrogue assembly. The drag of the paradrogue assembly was determined to range from 200 to 450 lbf at airspeeds from 170 to 250 KIAS. Analysis of the drag data resulted in a single drag coefficient of 0.0056 for the paradrogue assembly that adequately matched the calculated drag for all flight conditions. The drag relief provided to the tanker airplane when a receiver airplane engaged the paradrogue is also documented from 35 to 270 lbf at the various flight conditions tested. The results support the development of accurate aerodynamic models to be used in refueling simulations and control laws for fully autonomous refueling.

Analysis of Air Force Secondary Power Logistics Solution Contract

DTIC Science & Technology

2010-05-21

IL 62225 SUBJECT: Audit. Analysis of Air Force Secondary Power Logistics Solution Contract, 748th Supply Chain Management Group, Hill Air Fon:r... Power Logis.tics Solution Contnict. 748111 Supply Ch.,in Management Group. !-lill Air FOfC! BII.SI!, UT (Project 02009· DOOOCH·0213.000) I. AUlIctlcd...00-00-2010 to 00-00-2010 4. TITLE AND SUBTITLE Analysis of Air Force Secondary Power Logistics Solution Contract 5a. CONTRACT NUMBER 5b. GRANT

Aeronomy coexperiments on drag-free satellites with proportional thrusters: GP-B and STEP

NASA Astrophysics Data System (ADS)

Jafry, Yusuf R.

1992-01-01

GP-B and STEP are two proposed experiments in basic physics which will utilize drag-free spacecraft in 600 km polar orbits around the earth. By monitoring the activity of the drag-free compensators, it will be possible to obtain in situ drag measurements from which variations in atmospheric density and winds can be observed with unprecedented resolution. With the inclusion of neutral mass spectrometers, it will be possible to distinguish the effects of the various species; thus significantly enhancing the aeronomic contribution of the drag data. The drag information will be contained in both the motion of the spacecraft about the drag-free proof-mass, and the thruster activity. A new smoother has been developed to deconvolve the net forces from the proof-mass sensor measurements. The smoother is an adaptation of an existing algorithm, which has been tailored to cater for completely unknown inputs. After the deconvolution process, the thrust force must be subtracted from the net force to yield the estimate of the drag. Hence, the accuracy of the drag measurements will ultimately depend on the accuracy of the thruster calibration. Perhaps the largest source of uncertainty will be associated with impingement of the thruster plumes on the spacecraft surfaces. It is thus desirable to model these effects. Owing to the low thrust levels, the flow through the GP-B nozzles will be highly rarefied, rendering the conventional continuum model invalid. An experimental procedure was thus devised to characterize the plume structure. A mass spectrometer, modified from a helium leak detector, was used to measure the mass flux distribution. The observed plume shapes were found to be essentially unchanged with mass flow. The experimental results were compared with Boyd's DSMC solutions pertaining to the nozzle geometries and flow conditions used in the experiments. For the assumption of diffuse interaction with the nozzle walls, the numerical results were found to be in excellent

Quantifying drag on wellbore casings in moving salt sheets

NASA Astrophysics Data System (ADS)

Weijermars, R.; Jackson, M. P. A.; Dooley, T. P.

2014-08-01

Frontier hydrocarbon development projects in the deepwater slopes of the Gulf of Mexico Basin, Santos Basin and Lower Congo Basin all require wells to cross ductile layers of autochthonous or allochthonous salt moving at peak rates of 100 mm yr-1. The Couette-Poiseuille number is introduced here to help pinpoint the depth of shear stress reversal in such salt layers. For any well-planned through salt, the probable range of creep forces of moving salt needs to be taken into account when designing safety margins and load-factor tolerance of the well casing. Drag forces increase with wellbore diameter, but more significantly with effective viscosity and speed of the creeping salt layer. The potential drag forces on cased wellbores in moving salt sheets are estimated analytically using a range of salt viscosities (1015-1019 Pa s) and creep rates (0-10 mm yr-1). Drag on perfectly rigid casing of infinite strength may reach up to 13 Giga Newton per meter wellbore length in salt having a viscosity of 1019 Pa s. Well designers may delay stress accumulations due to salt drag when flexible casing accommodates some of the early displacement and strain. However, all creeping salt could displace, fracture and disconnect well casing, eventually. The shear strength of typical heavy duty well casing (about 1000 MPa) can be reached due to drag by moving salt. Internal flow of salt will then fracture the casing near salt entry and exit points, but the structural damage is likely to remain unnoticed early in the well-life when the horizontal shift of the wellbore is still negligibly small (at less than 1 cm yr-1). Disruption of casing and production flow lines within the anticipated service lifetime of a well remains a significant risk factor within distinct zones of low-viscosity salt which may reach ultrafast creep rates of 100 mm yr-1.

Management and Oversight of Services Acquisition Within the United States Air Force

DTIC Science & Technology

2008-12-01

Air Mobility Command AFDW Air Force District of Washington AFSPC Air Force Space Command AT&L Acquisition Technologies and Logistics CPM ...were commonly performed in industry. The types of services included advertising for Navy recruitment, custodial services on Air Force bases, and on

A preliminary investigation of the drag and ventilation characteristics of livestock haulers

NASA Technical Reports Server (NTRS)

Hoffman, J. A.; Sandin, D. R.

1983-01-01

A wind tunnel evaluation of the drag and ventilation characteristics of a conventional (unmodified) and five modified subscale model livestock haulers at 0 deg yaw angle has been made. The unmodified livestock hauler has a relatively high drag coefficient, and a low velocity recirculation region exists in the forward portion of the hauler. The use of a streamlined forebody and enclosed gap reduced the drag coefficient of one model by 42% and improved the rate at which contaminants can be flushed from the cargo compartment by a factor of 2.5. From the limited data obtained, any increase in the fraction of open area of the trailer sides was found to improve the trailer ventilation. The use of a ram air inlet can improve the ventilation within the hauler and remove the low velocity recirculation region at the expense of a modest increase in the truck's drag coefficient. A mathematical model for vehicles with ram air or NACA submerged inlets was developed and appears to adequately predict the ventilation characteristics of livestock haulers.

Drag Measurements over Embedded Cavities in a Low Reynolds Number Couette Flow

NASA Astrophysics Data System (ADS)

Gilmer, Caleb; Lang, Amy; Jones, Robert

2010-11-01

Recent research has revealed that thin-walled, embedded cavities in low Reynolds number flow have the potential to reduce the net viscous drag force acting on the surface. This reduction is due to the formation of embedded vortices allowing the outer flow to pass over the surface via a roller bearing effect. It is also hypothesized that the scales found on butterfly wings may act in a similar manner to cause a net increase in flying efficiency. In this experimental study, rectangular embedded cavities were designed as a means of successfully reducing the net drag across surfaces in a low Reynolds number flow. A Couette flow was generated via a rotating conveyor belt immersed in a tank of high viscosity mineral oil above which the plates with embedded cavities were placed. Drag induced on the plate models was measured using a force gauge and compared directly to measurements acquired over a flat plate. Various cavity aspect ratios and gap heights were tested in order to determine the conditions under which the greatest drag reductions occurred.

Drag bit construction

DOEpatents

Hood, Michael

1986-01-01

A mounting movable with respect to an adjacent hard face has a projecting drag bit adapted to engage the hard face. The drag bit is disposed for movement relative to the mounting by encounter of the drag bit with the hard face. That relative movement regulates a valve in a water passageway, preferably extending through the drag bit, to play a stream of water in the area of contact of the drag bit and the hard face and to prevent such water play when the drag bit is out of contact with the hard face.

32 CFR 855.7 - Conditions for use of Air Force airfields.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 32 National Defense 6 2010-07-01 2010-07-01 false Conditions for use of Air Force airfields. 855.7 Section 855.7 National Defense Department of Defense (Continued) DEPARTMENT OF THE AIR FORCE AIRCRAFT CIVIL AIRCRAFT USE OF UNITED STATES AIR FORCE AIRFIELDS Civil Aircraft Landing Permits § 855.7...

32 CFR 855.7 - Conditions for use of Air Force airfields.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 32 National Defense 6 2013-07-01 2013-07-01 false Conditions for use of Air Force airfields. 855.7 Section 855.7 National Defense Department of Defense (Continued) DEPARTMENT OF THE AIR FORCE AIRCRAFT CIVIL AIRCRAFT USE OF UNITED STATES AIR FORCE AIRFIELDS Civil Aircraft Landing Permits § 855.7...

32 CFR 855.7 - Conditions for use of Air Force airfields.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 32 National Defense 6 2014-07-01 2014-07-01 false Conditions for use of Air Force airfields. 855.7 Section 855.7 National Defense Department of Defense (Continued) DEPARTMENT OF THE AIR FORCE AIRCRAFT CIVIL AIRCRAFT USE OF UNITED STATES AIR FORCE AIRFIELDS Civil Aircraft Landing Permits § 855.7...

32 CFR 855.7 - Conditions for use of Air Force airfields.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 32 National Defense 6 2012-07-01 2012-07-01 false Conditions for use of Air Force airfields. 855.7 Section 855.7 National Defense Department of Defense (Continued) DEPARTMENT OF THE AIR FORCE AIRCRAFT CIVIL AIRCRAFT USE OF UNITED STATES AIR FORCE AIRFIELDS Civil Aircraft Landing Permits § 855.7...

32 CFR 855.7 - Conditions for use of Air Force airfields.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 32 National Defense 6 2011-07-01 2011-07-01 false Conditions for use of Air Force airfields. 855.7 Section 855.7 National Defense Department of Defense (Continued) DEPARTMENT OF THE AIR FORCE AIRCRAFT CIVIL AIRCRAFT USE OF UNITED STATES AIR FORCE AIRFIELDS Civil Aircraft Landing Permits § 855.7...

Air Force Reserve Command

Science.gov Websites

Page Get One Now AFR Mission and Vision Statement Social Media Facebook Logo #AlwaysThere Facebook Logo Technician job vacancies on USAJobs.gov 2017 AFR Modernization Book AFR Vision and Guiding Principles 2013 AFR Vision Update 2015 Contact Air Force Reserve AFRC Public Affairs AF Reserve Recruiting Service

Drag reduction using wrinkled surfaces in high Reynolds number laminar boundary layer flows

NASA Astrophysics Data System (ADS)

Raayai-Ardakani, Shabnam; McKinley, Gareth H.

2017-09-01

Inspired by the design of the ribbed structure of shark skin, passive drag reduction methods using stream-wise riblet surfaces have previously been developed and tested over a wide range of flow conditions. Such textures aligned in the flow direction have been shown to be able to reduce skin friction drag by 4%-8%. Here, we explore the effects of periodic sinusoidal riblet surfaces aligned in the flow direction (also known as a "wrinkled" texture) on the evolution of a laminar boundary layer flow. Using numerical analysis with the open source Computational Fluid Dynamics solver OpenFOAM, boundary layer flow over sinusoidal wrinkled plates with a range of wavelength to plate length ratios ( λ / L ), aspect ratios ( 2 A / λ ), and inlet velocities are examined. It is shown that in the laminar boundary layer regime, the riblets are able to retard the viscous flow inside the grooves creating a cushion of stagnant fluid that the high-speed fluid above can partially slide over, thus reducing the shear stress inside the grooves and the total integrated viscous drag force on the plate. Additionally, we explore how the boundary layer thickness, local average shear stress distribution, and total drag force on the wrinkled plate vary with the aspect ratio of the riblets as well as the length of the plate. We show that riblets with an aspect ratio of close to unity lead to the highest reduction in the total drag, and that because of the interplay between the local stress distribution on the plate and stream-wise evolution of the boundary layer the plate has to exceed a critical length to give a net decrease in the total drag force.

Large-scale control strategy for drag reduction in turbulent channel flows

NASA Astrophysics Data System (ADS)

Yao, Jie; Chen, Xi; Thomas, Flint; Hussain, Fazle

2017-06-01

In a recent article, Canton et al. [J. Canton et al., Phys. Rev. Fluids 1, 081501(R) (2016), 10.1103/PhysRevFluids.1.081501] reported significant drag reduction in turbulent channel flow by using large-scale, near-wall streamwise swirls following the control strategy of Schoppa and Hussain [W. Schoppa and F. Hussain, Phys. Fluids 10, 1049 (1998), 10.1063/1.869789] for low Reynolds numbers only, but found no drag reduction at high friction Reynolds numbers (Reτ=550 ). Here we show that the lack of drag reduction at high Re observed by Canton et al. is remedied by the proper choice of the large-scale control flow. In this study, we apply near-wall opposed wall-jet forcing to achieve drag reduction at the same (high) Reynolds number where Canton et al. found no drag reduction. The steady excitation is characterized by three control parameters, namely, the wall-jet-forcing amplitude A+, the spanwise spacing Λ+, and the wall jet height yc+ (+ indicates viscous scaling); the primary difference between Schoppa and Hussain's work (also that of Canton et al.) and this Rapid Communication is the emphasis on the explicit choice of yc+ here. We show as an example that with a choice of A+≈0.015 ,Λ+≈1200 , and yc+≈30 the flow control definitely suppresses the wall shear stress at a series of Reynolds numbers, namely, 19 %,14 % , and 12 % drag reductions at Reτ=180 , 395, and 550, respectively. Further study should explore optimization of these parameter values.

Processing Multiyear Procurement (MYP) Submissions - A Handbook for Air Force Program Offices

DTIC Science & Technology

1985-05-01

Contracting and Manufacturing Policy; "Policy Letter 84-1l - Multiyear Contracting Guidance" Headquarters, United States Air Force, Washington, D.C...supplement to Air Force FAR Sup No. 17.191: as enclosed in Thomas E. Lloyd, Colonel, USAF, Assistant DCS/Contracting , and Manufacturing , "DCS...Contracting and Manufacturing Policy Letter 84-16, Multiyear Contracting Guidance." Headquarters, Air Force Systems Command, Andrew Air Force Base

Task force on deterrence of air piracy : final report.

DOT National Transportation Integrated Search

1978-11-01

In February 1969, as the frequency of hijacking of U.S. air carrier aircraft was rising to an all-time high, the Federal Aviation Administration established a multi-disciplinary Task Force on Deterrence of Air Piracy. The work of the Task Force in de...

Whose drag is it anyway? Drag kings and monarchy in the UK.

PubMed

Willox, Annabelle

2002-01-01

This chapter will show that the term "drag" in drag queen has a different meaning, history and value to the term "drag" in drag king. By exposing this basic, yet fundamental, difference this paper will expose the problems inherent in the assumption of parity between the two forms of drag. An exposition of how camp has been used to comprehend and theorise drag queens will facilitating an understanding of the parasitic interrelationship between camp and drag queen performances, while a critique of "Towards a Butch-Femme Aesthetic," by Sue Ellen Case, will point out the problematic assumptions made about camp when attributed to a cultural location different to the drag queen. By interrogating the historical, cultural and theoretical similarities and differences between drag kings, butches, drag queens and femmes this paper will expose the flawed assumption that camp can be attributed to all of the above without proviso, and hence expose why drag has a fundamentally different contextual meaning for kings and queens. This chapter will conclude by examining the work of both Judith Halberstam and Biddy Martin and the practical examples of drag king and queen performances provided at the UK drag contest held at The Fridge in Brixton, London on 23 June 1999.

The Air Force Handbook 2007

DTIC Science & Technology

2007-01-01

sPEcIfIcATIOns Weight 51,000 lb. (22,950 kg ) Range 800 miles (695 nautical miles) Armament One 30 mm GAU-8/A seven-barrel Gatling gun with over 1,150...battlefield air and space profession- als who bring unequaled accuracy, responsiveness, flexibility, and persistence to the Joint warfight. LOSS Of...approximately $12.4 billion. This loss of buying power reduced Air Force Program content by an additional $10 billion per year. Base Realignment

Annotated Bibliography of the Air Force Human Resources Laboratory Technical Reports - 1979.

DTIC Science & Technology

1981-05-01

Force Human Resources Laboratory, March 1980. (Covers all AFHRL projects.) NTIS. This document provides the academic and industrial R&D community with...D-AI02 04𔃾 AIR FORCE HUMAN RESOURCES LAB BROOKS AF TX F/G 5/2 ANNOTATED BIBLIOGRAPHY OF THE AIR FORCE HUMAN RESOURCES LABORAT--ETC(U) MAY 81 E M...OF THE AIR FORCE HUMAN RESOURCES LABORATORY TECHNICAL REPORTS - 1979U M By M Esther M. Barlow A N TECHNICAL SERVICES DIVISION Brooks Air Force Base

Drag bit construction

DOEpatents

Hood, M.

1986-02-11

A mounting movable with respect to an adjacent hard face has a projecting drag bit adapted to engage the hard face. The drag bit is disposed for movement relative to the mounting by encounter of the drag bit with the hard face. That relative movement regulates a valve in a water passageway, preferably extending through the drag bit, to play a stream of water in the area of contact of the drag bit and the hard face and to prevent such water play when the drag bit is out of contact with the hard face. 4 figs.

32 CFR 728.25 - Army and Air Force National Guard personnel.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 32 National Defense 5 2013-07-01 2013-07-01 false Army and Air Force National Guard personnel. 728... Guard Personnel § 728.25 Army and Air Force National Guard personnel. (a) Medical and dental care. Upon... Care) and AFR 168-6 (Persons Authorized Medical Care) to members of the Army and Air Force National...

32 CFR 728.25 - Army and Air Force National Guard personnel.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 32 National Defense 5 2012-07-01 2012-07-01 false Army and Air Force National Guard personnel. 728... Guard Personnel § 728.25 Army and Air Force National Guard personnel. (a) Medical and dental care. Upon... Care) and AFR 168-6 (Persons Authorized Medical Care) to members of the Army and Air Force National...

32 CFR 728.25 - Army and Air Force National Guard personnel.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 32 National Defense 5 2010-07-01 2010-07-01 false Army and Air Force National Guard personnel. 728... Guard Personnel § 728.25 Army and Air Force National Guard personnel. (a) Medical and dental care. Upon... Care) and AFR 168-6 (Persons Authorized Medical Care) to members of the Army and Air Force National...

32 CFR 728.25 - Army and Air Force National Guard personnel.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 32 National Defense 5 2011-07-01 2011-07-01 false Army and Air Force National Guard personnel. 728... Guard Personnel § 728.25 Army and Air Force National Guard personnel. (a) Medical and dental care. Upon... Care) and AFR 168-6 (Persons Authorized Medical Care) to members of the Army and Air Force National...

The Air Force Research Laboratory’s In-Space Propulsion Program

DTIC Science & Technology

2015-02-01

Air Force Research Laboratory (AFMC) AFRL /RQRS 1 Ara...MONITOR’S ACRONYM(S) Air Force Research Laboratory (AFMC) AFRL /RQR 5 Pollux Drive 11. SPONSOR/MONITOR’S REPORT Edwards AFB CA 93524-7048 NUMBER(S) AFRL ...illustrate the rationale behind AFRL’s technology development strategy. INTRODUCTION The Air Force Research Laboratory ( AFRL ) is the technology

32 CFR 644.475 - Excessing Army military and Air Force property.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 32 National Defense 4 2010-07-01 2010-07-01 true Excessing Army military and Air Force property... the Related Land) § 644.475 Excessing Army military and Air Force property. The procedures for placing... commander concerned is required. When, under AFR 87-4, the responsible DE is called upon by the Air Force...

London 2012 Paralympic swimming: passive drag and the classification system.

PubMed

Oh, Yim-Taek; Burkett, Brendan; Osborough, Conor; Formosa, Danielle; Payton, Carl

2013-09-01

The key difference between the Olympic and Paralympic Games is the use of classification systems within Paralympic sports to provide a fair competition for athletes with a range of physical disabilities. In 2009, the International Paralympic Committee mandated the development of new, evidence-based classification systems. This study aims to assess objectively the swimming classification system by determining the relationship between passive drag and level of swimming-specific impairment, as defined by the current swimming class. Data were collected on participants at the London 2012 Paralympic Games. The passive drag force of 113 swimmers (classes 3-14) was measured using an electro-mechanical towing device and load cell. Swimmers were towed on the surface of a swimming pool at 1.5 m/s while holding their most streamlined position. Passive drag ranged from 24.9 to 82.8 N; the normalised drag (drag/mass) ranged from 0.45 to 1.86 N/kg. Significant negative associations were found between drag and the swimming class (τ = -0.41, p < 0.01) and normalised drag and the swimming class (τ = -0.60, p < 0.01). The mean difference in drag between adjacent classes was inconsistent, ranging from 0 N (6 vs 7) to 11.9 N (5 vs 6). Reciprocal Ponderal Index (a measure of slenderness) correlated moderately with normalised drag (r(P) = -0.40, p < 0.01). Although swimmers with the lowest swimming class experienced the highest passive drag and vice versa, the inconsistent difference in mean passive drag between adjacent classes indicates that the current classification system does not always differentiate clearly between swimming groups.

Air Force Materiel Command: A Survey of Performance Measures

DTIC Science & Technology

2004-03-12

AIR FORCE MATERIEL COMMAND: A SURVEY OF PERFORMANCE MEASURES THESIS Marcia Leonard, Capt...AFIT/GLM/ENS/04-10 AIR FORCE MATERIEL COMMAND: A SURVEY OF PERFORMANCE MEASURES THESIS Presented to the Faculty...SURVEY OF PERFORMANCE MEASURES Marcia Leonard, BS Capt, USAF Approved: //signed// 12 March 2004

Modeling U.S. Air Force Occupational Health Costs

DTIC Science & Technology

2009-03-01

for the 75th Aerospace Medicine Group, Hill Air Force Base, Utah. Bioenvironmental engineers sought a more robust cost comparison tool, allowing...to Major Feltenberger and Major Johns at the Air Force Medical Operations Agency and Captain Batchellor from the 75th Aerospace Medicine Squadron...resources on support functions is challenging, and rightly so. In a sense, commanders are fiduciaries to the taxpayers and must responsibly spend

The Air Force and Diversity: The Awkward Embrace

DTIC Science & Technology

2014-06-01

Space Power Journal | 105 Streeter The Air Force and Diversity Feature eling an intelligence problem at the tactical level, through developing a...careers.2 Discordance exists between Air Force intentions vis-à-vis diversity and any effective programs and policies to retain and develop a di...though the service has initiated formal di- versity efforts, recommended policy and development programs may help develop and retain competent

76 FR 22083 - U.S. Air Force Academy Board of Visitors Notice of Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2011-04-20

...'t Tell'' way ahead; an Air Force perspective on Diversity; an Ethics briefing; and Air Force Academy... DEPARTMENT OF DEFENSE Department of the Air Force U.S. Air Force Academy Board of Visitors Notice of Meeting AGENCY: U.S. Air Force Academy Board of Visitors. ACTION: Meeting notice. SUMMARY...

76 FR 71333 - U.S. Air Force Academy Board of Visitors Notice of Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2011-11-17

... Don't Tell;'' a National and Air Force perspective on Diversity; the Air Force Academy Athletic... DEPARTMENT OF DEFENSE Department of the Air Force U.S. Air Force Academy Board of Visitors Notice of Meeting AGENCY: U.S. Air Force Academy Board of Visitors. ACTION: Meeting notice. SUMMARY: In...

Self-determined shapes and velocities of giant near-zero drag gas cavities

PubMed Central

Vakarelski, Ivan U.; Klaseboer, Evert; Jetly, Aditya; Mansoor, Mohammad M.; Aguirre-Pablo, Andres A.; Chan, Derek Y. C.; Thoroddsen, Sigurdur T.

2017-01-01

Minimizing the retarding force on a solid moving in liquid is the canonical problem in the quest for energy saving by friction and drag reduction. For an ideal object that cannot sustain any shear stress on its surface, theory predicts that drag force will fall to zero as its speed becomes large. However, experimental verification of this prediction has been challenging. We report the construction of a class of self-determined streamlined structures with this free-slip surface, made up of a teardrop-shaped giant gas cavity that completely encloses a metal sphere. This stable gas cavity is formed around the sphere as it plunges at a sufficiently high speed into the liquid in a deep tank, provided that the sphere is either heated initially to above the Leidenfrost temperature of the liquid or rendered superhydrophobic in water at room temperature. These sphere-in-cavity structures have residual drag coefficients that are typically less than 110 those of solid objects of the same dimensions, which indicates that they experienced very small drag forces. The self-determined shapes of the gas cavities are shown to be consistent with the Bernoulli equation of potential flow applied on the cavity surface. The cavity fall velocity is not arbitrary but is uniquely predicted by the sphere density and cavity volume, so larger cavities have higher characteristic velocities. PMID:28913434

On the development of lift and drag in a rotating and translating cylinder

NASA Astrophysics Data System (ADS)

Martin-Alcantara, Antonio; Sanmiguel-Rojas, Enrique; Fernandez-Feria, Ramon

2014-11-01

The two-dimensional flow around a rotating cylinder is investigated numerically using a vorticity forces formulation with the aim of analyzing the flow structures, and their evolutions, that contribute to the lift and drag forces on the cylinder. The Reynolds number, based on the cylinder diameter and steady free-stream speed, considered is Re = 200 , while the non-dimensional rotation rate (ratio of the surface speed and free-stream speed) selected were α = 1 and 3. For α = 1 the wake behind the cylinder for the fully developed flow is oscillatory due to vortex shedding, and so are the lift and drag forces. For α = 3 the fully developed flow is steady with constant (high) lift and (low) drag. Each of these cases is considered in two different transient problems, one with angular acceleration of the cylinder and constant speed, and the other one with translating acceleration of the cylinder and constant rotation. Special attention is paid to explaining the mechanisms of vortex shedding suppression for high rotation (when α = 3) and its relation to the mechanisms by which the lift is enhanced and the drag is almost suppressed when the fully developed flow is reached. Supported by the Ministerio de Economia y Competitividad of Spain Grant No. DPI2013-40479-P.

Verification of drag-reduction capabilities of stiff compliant coatings in air flow at moderate speeds

NASA Astrophysics Data System (ADS)

Boiko, Andrey V.; Kulik, Victor M.; Chun, Ho-Hwan; Lee, Inwon

2011-12-01

Skin frictional drag reduction efficiency of "stiff" compliant coating was investigated in a wind tunnel experiment. Flat plate compliant coating inserts were installed in a wind tunnel and the measurements of skin frictional drag and velocity field were carried out. The compliant coatings with varying viscoelastic properties had been prepared using different composition. In order to optimize the coating thickness, the most important design parameter, the dynamic viscoelastic properties had been determined experimentally. The aging of the materials (variation of their properties) during half a year was documented as well. A design procedure proposed by Kulik et al. (2008) was applied to get an optimal value for the coating thickness. Along with the drag measurement using the strain balance, velocity and pressure were measured for different coatings. The compliant coatings with the thickness h = 7mm achieved 4~5% drag reduction within a velocity range 30~40 m/s. The drag reduction mechanism of the attenuation of turbulence velocity fluctuations due to the compliant coating was demonstrated. It is envisioned that larger drag reduction effect is obtainable at higher flow velocities for high speed trains and subsonic aircrafts.

Drag on a Satellite Moving across a Spherical Galaxy: Tidal and Frictional Forces in Short-lived Encounters

NASA Astrophysics Data System (ADS)

Colpi, Monica; Pallavicini, Andrea

1998-07-01

The drag force on a satellite of mass M moving with speed V in the gravitational field of a spherically symmetric background of stars is computed. During the encounter, the stars are subject to a time-dependent force that alters their equilibrium. The resulting distortion in the stellar density field acts back to produce a force FΔ that decelerates the satellite. This force is computed using a perturbative technique known as linear response theory. In this paper, we extend the formalism of linear response to derive the correct expression for the back-reaction force FΔ that applies when the stellar system is described by an equilibrium one-particle distribution function. FΔ is expressed in terms of a suitable correlation function that couples the satellite dynamics to the unperturbed dynamics of the stars. At time t, the force depends upon the whole history of the composite system. In the formalism, we account for the shift of the stellar center of mass resulting from linear momentum conservation. The self-gravity of the response is neglected since it contributes to a higher order in the perturbation. Linear response theory applies also to the case of a satellite orbiting outside the spherical galaxy. The case of a satellite moving on a straight line, at high speed relative to the stellar dispersion velocity, is explored. We find that the satellite during its passage raises (1) global tides in the stellar distribution and (2) a wake, i.e., an overdense region behind its trail. If the satellite motion is external to the galaxy, it suffers a dissipative force that is not exclusively acting along V but acquires a component along R, the position vector relative to the center of the spherical galaxy. We derive the analytical expression of the force in the impulse approximation. In penetrating short-lived encounters, the satellite moves across the stellar distribution and the transient wake excited in the density field is responsible for most of the deceleration. We

Effects of Forced Air Warming on Airflow around the Operating Table.

PubMed

Shirozu, Kazuhiro; Kai, Tetsuya; Setoguchi, Hidekazu; Ayagaki, Nobuyasu; Hoka, Sumio

2018-01-01

Forced air warming systems are used to maintain body temperature during surgery. Benefits of forced air warming have been established, but the possibility that it may disturb the operating room environment and contribute to surgical site contamination is debated. The direction and speed of forced air warming airflow and the influence of laminar airflow in the operating room have not been reported. In one institutional operating room, we examined changes in airflow speed and direction from a lower-body forced air warming device with sterile drapes mimicking abdominal surgery or total knee arthroplasty, and effects of laminar airflow, using a three-dimensional ultrasonic anemometer. Airflow from forced air warming and effects of laminar airflow were visualized using special smoke and laser light. Forced air warming caused upward airflow (39 cm/s) in the patient head area and a unidirectional convection flow (9 to 14 cm/s) along the ceiling from head to foot. No convection flows were observed around the sides of the operating table. Downward laminar airflow of approximately 40 cm/s counteracted the upward airflow caused by forced air warming and formed downward airflow at 36 to 45 cm/s. Downward airflows (34 to 56 cm/s) flowing diagonally away from the operating table were detected at operating table height in both sides. Airflow caused by forced air warming is well counteracted by downward laminar airflow from the ceiling. Thus it would be less likely to cause surgical field contamination in the presence of sufficient laminar airflow.

Predicting lethal entanglements as a consequence of drag from fishing gear.

PubMed

van der Hoop, Julie M; Corkeron, Peter; Henry, Allison G; Knowlton, Amy R; Moore, Michael J

2017-02-15

Large whales are frequently entangled in fishing gear and sometimes swim while carrying gear for days to years. Entangled whales are subject to additional drag forces requiring increased thrust power and energy expenditure over time. To classify entanglement cases and aid potential disentanglement efforts, it is useful to know how long an entangled whale might survive, given the unique configurations of the gear they are towing. This study establishes an approach to predict drag forces on fishing gear that entangles whales, and applies this method to ten North Atlantic right whale cases to estimate the resulting increase in energy expenditure and the critical entanglement duration that could lead to death. Estimated gear drag ranged 11-275N. Most entanglements were resolved before critical entanglement durations (mean±SD 216±260days) were reached. These estimates can assist real-time development of disentanglement action plans and U.S. Federal Serious Injury assessments required for protected species. Copyright © 2016 Elsevier Ltd. All rights reserved.

Lift, drag and thrust measurement in a hypersonic impulse facility

NASA Technical Reports Server (NTRS)

Tuttle, S. L.; Mee, D. J.; Simmons, J. M.

1995-01-01

This paper reports the extension of the stress wave force balance to the measurement of forces on models which are non-axisymmetric or which have non-axisymmetric load distributions. Recent results are presented which demonstrate the performance of the stress wave force balance for drag measurement, for three-component force measurement and preliminary results for thrust measurement on a two-dimensional scramjet nozzle. In all cases, the balances respond within a few hundred microseconds.

Back to the Future: Does History Support the Expeditionary Air Force Concept?

DTIC Science & Technology

2000-04-01

Operations Forces 550, “Agile Combat Support,” Mr. Ron Orr, USAF/IL, 2 Feb 00. 4 Davis, pg. 11. 5 Toulmin , H.A., Jr., Air Service, American...John A., “The Expeditionary Air Force Takes Shape,” Air Force Magazine, Vol. 80, No. 6, June 1997. Toulmin , H.A., Jr., Air Service, American

Spiritual Development for Strategic Leadership in the Air Force

DTIC Science & Technology

2010-03-01

millionaire civilian pilot who had grown close to senior Air Force officials and the Thunderbirds.”8 The Thunderbirds are the Air Force’s high...integrated with the other well- known streams of development: cognitive, social , emotional, and moral. The name commonly given is spiritual...and socialize the Air Force core values of “Integrity First, Service Before Self, and Excellence in All We Do,” adopted in 1997. This document states

2009 Strategic Plan, Air Force District of Washington (AFDW)

DTIC Science & Technology

2009-09-11

JTF CapMed . As the Air Force single voice for Joint matters in the NCR, AFDW has a critical responsibility to protect and enhance the Air...and its surrounding counties, is a critical Area of Responsibility (AOR) for US military organizations. It is the central hub of US political and...NCR and worldwide. Furthermore, AFDW presents forces to Joint Task Force-National Capital Region Medical Command (JTF CapMed ) and, through the

Radiation Pressure, Poynting-Robertson Drag, and Solar Wind Drag in the Restricted Three-Body Problem

NASA Technical Reports Server (NTRS)

Liou, Jer-Chyi; Zook, Herbert A.; Jackson, A. A.

1995-01-01

In this paper, we examine the effects of radiation pressure, Poynting-Robertson (PR) drag, and solar wind drag on dust grains trapped in mean motion resonances with the Sun and Jupiter in the restricted (negligible dust mass) three-body Problem. We especially examine the evolution of dust grains in the 1:1 resonance. As a first step, the Sun and Jupiter are idealized to both be in circular orbit about a common center of mass (circular restricted three-body problem). From the equation of motion of the dust particle in the rotating reference frame, the drag-induced time rate of change of its Jacobi "constant," C, is then derived and expressed in spherical coordinates. This new mathematical expression in spherical coordinates shows that C, in the 1:1 resonance, both oscillates and secularly increases with increasing time. The new expression gives rise to an easy understanding of how an orbit evolves when the radiation force and solar wind drag are included. All dust grain orbits are unstable in time when PR and solar wind drag are included in the Sun-Jupiter-dust system. Tadpole orbits evolve into horseshoe orbits; and these orbits continuously expand in size to lead to close encounters with Jupiter. Permanent trapping is impossible. Orbital evolutions of a dust grain trapped in the 1:1 resonance in the planar circular, an inclined case, an eccentric case, and the actual Sun-Jupiter case are numerically simulated and compared with each other and show grossly similar time behavior. Resonances other than 1:1 are also explored with the new expression. Stable exterior resonance trapping may be possible under certain conditions. One necessary condition for such a trap is derived. Trapping in interior resonances is shown to be always unstable.

Automated design of minimum drag light aircraft fuselages and nacelles

NASA Technical Reports Server (NTRS)

Smetana, F. O.; Fox, S. R.; Karlin, B. E.

1982-01-01

The constrained minimization algorithm of Vanderplaats is applied to the problem of designing minimum drag faired bodies such as fuselages and nacelles. Body drag is computed by a variation of the Hess-Smith code. This variation includes a boundary layer computation. The encased payload provides arbitrary geometric constraints, specified a priori by the designer, below which the fairing cannot shrink. The optimization may include engine cooling air flows entering and exhausting through specific port locations on the body.

Parenting Attitudes of Expectant Couples Associated with the Air Force

DTIC Science & Technology

1992-05-01

child abuse . These factors are also associated with Air Force life. These inherent risk factors when coupled with negative or abusive parenting attitudes could lead to child abuse . Little attention has been given to parenting attitudes in the Air Force population. Data were collected from a convenience sample of 67 participants in either the new OB orientation classes or the prepared child birth classes at two Air Force bases in the Southwest. The instrument was the Adult-Adolescent Parenting Inventory

Active drag, useful mechanical power output and hydrodynamic force coefficient in different swimming strokes at maximal velocity.

PubMed

Kolmogorov, S V; Duplishcheva, O A

1992-03-01

By comparing the time of the same distance swum with and without an added resistance, under the assumption of an equal power output in both cases, the drag of 73 top swimmers was estimated. The active drag Fr(a.d.) at maximal swimming velocities varied considerably across strokes and individuals. In the females Fr(a.d.) ranged from 69.78 to 31.16 N in the front-crawl, from 83.04 to 37.78 N in dolphin, from 93.56 to 45.19 N in breaststroke, and from 65.51 to 37.79 N in back-stroke. In the males Fr(a.d.) ranged from 167.11 to 42.23 N in front-crawl, from 156.09 to 46.95 N in dolphin, from 176.87 to 55.61 N in breaststroke, and from 146.28 to 46.36 N in back-stroke. Also, the ratio of Fr(a.d.) to the passive drag Fr(a.d.) as determined for the analogical velocity in a tugging condition (in standard body position-front gliding) shows considerable individual variations. In the female swimmers variations in Fr(a.d.)/Fr(p.d.) ranged from 145.17 to 59.94% in front-crawl, from 192.39 to 85.57% in dolphin, from 298.03 to 124.50% in breaststroke, and from 162.87 to 85.61% in back-stroke. In the male swimmers variations in Fr(a.d.)/Fr(p.d.) ranged from 162.24 to 62.39% in front-crawl, from 191.70 to 70.38% in dolphin, from 295.57 to 102.83% in breaststroke, and from 198.82 to 74.48% in back-stroke. The main reason for such variations is found in the individual features of swimming technique and can be quantitatively estimated with the hydrodynamic force coefficient, which thus provides an adequate index of technique.

Focused Logistics; What the Air Force Brings to the Fight

DTIC Science & Technology

2002-04-09

Agency partnered to develop a Strategic Distribution Management Initiative that support the Air Force’s logistics transformation and is linked by Global Command and Control System and Global Combat Support System-Air Force.

DETAIL, CONTROL BOOTH, RP1 TANK FARM Edwards Air Force ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

DETAIL, CONTROL BOOTH, RP1 TANK FARM - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Combined Fuel Storage Tank Farm, Test Area 1-120, north end of Jupiter Boulevard, Boron, Kern County, CA

Comparison of Gravity Wave Temperature Variances from Ray-Based Spectral Parameterization of Convective Gravity Wave Drag with AIRS Observations

NASA Technical Reports Server (NTRS)

Choi, Hyun-Joo; Chun, Hye-Yeong; Gong, Jie; Wu, Dong L.

2012-01-01

The realism of ray-based spectral parameterization of convective gravity wave drag, which considers the updated moving speed of the convective source and multiple wave propagation directions, is tested against the Atmospheric Infrared Sounder (AIRS) onboard the Aqua satellite. Offline parameterization calculations are performed using the global reanalysis data for January and July 2005, and gravity wave temperature variances (GWTVs) are calculated at z = 2.5 hPa (unfiltered GWTV). AIRS-filtered GWTV, which is directly compared with AIRS, is calculated by applying the AIRS visibility function to the unfiltered GWTV. A comparison between the parameterization calculations and AIRS observations shows that the spatial distribution of the AIRS-filtered GWTV agrees well with that of the AIRS GWTV. However, the magnitude of the AIRS-filtered GWTV is smaller than that of the AIRS GWTV. When an additional cloud top gravity wave momentum flux spectrum with longer horizontal wavelength components that were obtained from the mesoscale simulations is included in the parameterization, both the magnitude and spatial distribution of the AIRS-filtered GWTVs from the parameterization are in good agreement with those of the AIRS GWTVs. The AIRS GWTV can be reproduced reasonably well by the parameterization not only with multiple wave propagation directions but also with two wave propagation directions of 45 degrees (northeast-southwest) and 135 degrees (northwest-southeast), which are optimally chosen for computational efficiency.

The Maharaja’s New AVTAAR: Air-Refuelling Strategy for the Indian Air Force

DTIC Science & Technology

2013-06-01

and Lolita C Baldor, "Boeing gets $35 Billion Air Force Tanker Order," Aviation on NBC News.com. Feruary 24, 2011. http://www.nbcnews.com/id/41766812...rakshak.com/NAVY/Ships/Active/156-Nicobar-Class.html (accessed March 23, 2013). Cassata, Donna, and Lolita C Baldor. "Boeing gets $35 Billion Air Force

Improving Development Teams to Support Deliberate Development of Air Force Officers

DTIC Science & Technology

2015-01-01

the USAF Cyber Force (Scott et al., 2010) • Understrength Air Force Officer Career Fields: A Force Management Approach ( Galway et al., 2005...D., “The New Way of Officer Assignments,” Air Force Magazine, June 1998, pp. 64–67. Galway , Lionel A., Richard J. Buddin, Michael R. Thirtle, Peter

Phoretic drag reduction of chemically active homogeneous spheres under force fields and shear flows

NASA Astrophysics Data System (ADS)

Yariv, Ehud; Kaynan, Uri

2017-01-01

Surrounded by a spherically symmetric solute cloud, chemically active homogeneous spheres do not undergo conventional autophoresis when suspended in an unbounded liquid domain. When exposed to external flows, solute advection deforms that cloud, resulting in a generally asymmetric distribution of diffusio-osmotic slip which, in turn, modifies particle motion. Inspired by classical forced-convection analyses [Acrivos and Taylor, Phys. Fluids 5, 387 (1962), 10.1063/1.1706630; Frankel and Acrivos, Phys. Fluids 11, 1913 (1968), 10.1063/1.1692218] we illustrate this phoretic phenomenon using two prototypic configurations, one where the particle sediments under a uniform force field and one where it is subject to a simple shear flow. In addition to the Péclet number Pe associated with the imposed flow, the governing nonlinear problem also depends upon α , the intrinsic Péclet number associated with the chemical activity of the particle. As in the forced-convection problems, the small-Péclet-number limit is nonuniform, breaking down at large distances away from the particle. Calculation of the leading-order autophoretic effects thus requires use of matched asymptotic expansions, the outer region being at distances that scale inversely with Pe and Pe1 /2 in the respective sedimentation and shear problems. In the sedimentation problem we find an effective drag reduction of fractional amount α /8 ; in the shear problem we find that the magnitude of the stresslet is decreased by a fractional amount α /4 . For a dilute particle suspension the latter result is manifested by a reduction of the effective viscosity.

TOTAL FORCE INTEGRATION: PROVIDING STABILITY FOR CITIZEN SOLDIERS IN AN EVER CHANGING AIR FORCE

DTIC Science & Technology

2016-10-01

Active Duty manpower vacancies, such as Air Force Reserve Officer Training Corps (AFROTC) instructor duties, are being filled through unique...has invested in a variety of ways to fill manpower gaps, to include using enlisted Active Duty members to conduct what was previously considered...entire Air Force airlift mission, resulting in substantial stressors on civilian careers and family life, which has always been the cornerstone of

Drag Coefficient and Foam in Hurricane Conditions.

NASA Astrophysics Data System (ADS)

Golbraikh, E.; Shtemler, Y.

2016-12-01

he present study is motivated by recent findings of saturation and even decrease in the drag coefficient (capping) in hurricane conditions, which is accompanied by the production of a foam layer on the ocean surface. As it is difficult to expect at present a comprehensive numerical modeling of the drag coefficient saturation that is followed by wave breaking and foam production, there is no complete confidence and understanding of the saturation phenomenon. Our semi-empirical model is proposed for the estimation of the foam impact on the variation of the effective drag coefficient, Cd , with the reference wind speed U10 in stormy and hurricane conditions. The proposed model treats the efficient air-sea aerodynamic roughness length as a sum of two weighted aerodynamic roughness lengths for the foam-free and foam-covered conditions. On the available optical and radiometric measurements of the fractional foam coverage,αf, combined with direct wind speed measurements in hurricane conditions, which provide the minimum of the effective drag coefficient, Cd for the sea covered with foam. The present model yields Cd10 versus U10 in fair agreement with that evaluated from both open-ocean and laboratory measurements of the vertical variation of mean wind speed in the range of U10 from low to hurricane speeds. The present approach opens opportunities for drag coefficient modeling in hurricane conditions and hurricane intensity estimation by the foam-coverage value using optical and radiometric measurements.

Sub-grid drag models for horizontal cylinder arrays immersed in gas-particle multiphase flows

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sarkar, Avik; Sun, Xin; Sundaresan, Sankaran

2013-09-08

Immersed cylindrical tube arrays often are used as heat exchangers in gas-particle fluidized beds. In multiphase computational fluid dynamics (CFD) simulations of large fluidized beds, explicit resolution of small cylinders is computationally infeasible. Instead, the cylinder array may be viewed as an effective porous medium in coarse-grid simulations. The cylinders' influence on the suspension as a whole, manifested as an effective drag force, and on the relative motion between gas and particles, manifested as a correction to the gas-particle drag, must be modeled via suitable sub-grid constitutive relationships. In this work, highly resolved unit-cell simulations of flow around an arraymore » of horizontal cylinders, arranged in a staggered configuration, are filtered to construct sub-grid, or `filtered', drag models, which can be implemented in coarse-grid simulations. The force on the suspension exerted by the cylinders is comprised of, as expected, a buoyancy contribution, and a kinetic component analogous to fluid drag on a single cylinder. Furthermore, the introduction of tubes also is found to enhance segregation at the scale of the cylinder size, which, in turn, leads to a reduction in the filtered gas-particle drag.« less

Transformation in the French Air Force in an Era of Change

DTIC Science & Technology

2008-01-01

Abria.indd 6 10/30/08 1:15:37 PM Transformation in the French Air Force in an Era of Change Général d’armée aérienne Stéphane Abrial, chef...l’armée l’air,” sponsored by the Centre d’études stratégiques aérospatiales, 3 June 2008. The French Air Force, like all defense organizations...related to our equipment, because the French aircraft Gen Stéphane Abrial is the chief of staff of the French Air Force. He completed the French Air

B-52 Stratofortress > U.S. Air Force > Fact Sheet Display

Science.gov Websites

Speeches Archive Former AF Top 3 Viewpoints and Speeches Air Force Warrior Games 2017 Events 2018 Air Force Strategic Documents Desert Storm 25th Anniversary Observances DoD Warrior Games Portraits in Courage

How Does the Air Force Create Effective Accountability for Initial Spares?

DTIC Science & Technology

1990-05-01

effective accountability for initial spares? AUTHOR: Pamela J. Henson, Civilian, USAF The accountability for acquisition cost , schedule, and...in place to allow the Program Manager to effectively manage this cost element. Initial spares have traditionally been managed in Air Force Logistics...at Maxwell Air Force Base. Pamela became the Chief, Cost Analysis Division at HQ Air Force Logistics Command in 1987, where she received the Civilian

Achieving the Air Force’s Energy Vision

DTIC Science & Technology

2011-01-01

sor of logistics and supply chain management at AFIT. The US Air Force is the largest con -sumer of energy in the federal gov-ernment, spending $9...technology, motors , advanced bat- teries, and ultracapacitors. AFIT is playing a critical role in meeting Air Force and industry demand for more...Flight Design displayed a parallel hybrid-electric propul- sion system with an ICE and electric motor (fig. 2) for a general aviation aircraft. A

COIN in Cyberspace: Focusing Air Force Doctrine Development

DTIC Science & Technology

2007-01-01

cyberspace and began codifying its cyber warfare doctrine. This effort is hampered, however, by a limited understanding of cyberspace by rank and file Air...Force members. Many believe cyberspace and cyber warfare are the responsibility of the communications community. If this new doctrine is to be...doctrine to build upon, the Air Force can create unity of effort among Airmen at all levels, ensure unity of purpose in the prosecution of cyber warfare , and

The Effects of Propulsive Jetting on Drag of a Streamlined body

NASA Astrophysics Data System (ADS)

Krieg, Michael; Mohseni, Kamran

2017-11-01

Recently an abundance of bioinspired underwater vehicles have emerged to leverage eons of evolution. Our group has developed a propulsion technique inspired by jellyfish and squid. Propulsive jets are generated by ingesting and expelling water from a flexible internal cavity. We have demonstrated thruster capabilities for maneuvering on AUV platforms, where the internal thruster geometry minimized forward drag; however, such a setup cannot characterize propulsive efficiency. Therefore, we created a new streamlined vehicle platform that produces unsteady jets for forward propulsion rather than maneuvering. The streamlined jetting body is placed in a water tunnel and held stationary while jetting frequency and background flow velocity are varied. For each frequency/velocity pair the flow field is measured around the surface and in the wake using PIV. Using the zero jetting frequency as a baseline for each background velocity, the passive body drag is related to the velocity distribution. For cases with active jetting the drag and jetting forces are estimated from the velocity field and compared to the passive case. For this streamlined body, the entrainment of surrounding flow into the propulsive jet can reduce drag forces in addition to the momentum transfer of the jet itself. Office of Naval Research.

The U.S. Air Force Aeromedical Evacuation Mission: A Mission for the Air Reserve Components

DTIC Science & Technology

2016-02-01

AU/ACSC/2016 AIR COMMAND AND STAFF COLLEGE AIR UNIVERSITY THE U.S. AIR FORCE AEROMEDICAL EVACUATION MISSION: A MISSION FOR THE AIR RESERVE...Aeromedical Evacuation ............................................................................................................. 7 The Current Problem...13 Evaluation

Air Force Handbook. 109th Congress

DTIC Science & Technology

2009-01-01

FY06 Combat Survivor Evader Locator (CSEL) Acquisition Status Capabilities/Profile Functions /Performance Parameters 38 • Air Force’s primary source for...Broadcast Service (GBS) Capabilities/Profile Acquisition Status Functions /Performance Parameters • Purchase Requirements (Phase 2): • 3 primary ...Operations (AF CONOPS) that support the CSAF and joint vision of combat operations. • AF CONOPS describe key Air Force mission and/or functional areas

Wireless Sensor Network Applications for the Combat Air Forces

DTIC Science & Technology

2006-06-13

WIRELESS SENSOR NETWORK APPLICATIONS FOR THE COMBAT AIR FORCES GRADUATE RESEARCH PROJECT...Government. AFIT/IC4/ENG/06-05 WIRELESS SENSOR NETWORK APPLICATIONS FOR THE COMBAT AIR FORCES GRADUATE RESEARCH PROJECT Presented to the...Major, USAF June 2006 APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED AFIT/IC4/ENG/06-05 WIRELESS SENSOR NETWORK APPLICATIONS

Helical Explosive Flux Compression Generator Research at the Air Force Research Laboratory

DTIC Science & Technology

1999-06-01

Air Force Research Laboratory Kirtland AFB...ORGANIZATION NAME(S) AND ADDRESS(ES) Directed Energy Directorate, Air Force Research Laboratory Kirtland AFB, NM 8. PERFORMING ORGANIZATION REPORT...in support of the Air Force Research Laboratory ( AFRL ) explosive pulsed power program. These include circuit codes such as Microcap and

Task analysis of Air Force pharmacy practice.

PubMed

Bartholomew, A; Sawyer, W T; Coats, L

1995-01-15

The frequency with which United States Air Force pharmacists perform specific professional tasks and the pharmacists' views as to the importance of those tasks were studied. A questionnaire was prepared that asked recipients to rate each of 36 tasks selected as representing the spectrum of practice activities. There were four categories of tasks: managerial tasks, dispensing tasks, drug information tasks, and patient care tasks. Recipients rated the tasks with respect to frequency of performance and importance on separate 6-point scales. The questionnaire was mailed in May 1991 to the 225 pharmacists then serving in the Air Force worldwide. Of the 225 questionnaires, 150 usable questionnaires were returned (response rate, 67%). All the tasks in the survey were performed by at least one Air Force pharmacy officer, although the frequency of task performance varied. In particular, the frequency of many patient care tasks was low. All the tasks were perceived to have some importance, but drug information tasks were rated as being significantly more important than tasks in the other categories; patient care tasks were rated lowest in importance. The results varied with the respondents' demographic characteristics. Pharmacy officers with more years of service, more senior positions, higher rank, or an advanced degree in a field other than pharmacy tended to give responses that diverged from those of the population. A 1991 survey showed an awareness among Air Force pharmacists of the need to orient practice around patient care; however, they were not spending substantial time on patient care and tended to view it as less important than more traditional pharmacy tasks.

Air Force Air Refueling for Naval Operations: History, Practice, and Recommendations

DTIC Science & Technology

1990-08-01

Air Force Air Refueling 0 ELECTE C4 N 910U for BU Naval Operations History, Practice, and Recommendations UtMON STA~IMENT X [ Apov.e ,opu,. Lt Col...as three hose reels provide redundancy over just one. 13. Be used in coordination with carriler -launched buddy tankers, there- by providing the

The Relationship between Power Generated by Thrust and Power to Overcome Drag in Elite Short Distance Swimmers.

PubMed

Gatta, Giorgio; Cortesi, Matteo; Zamparo, Paola

At constant average speed (v), a balance between thrust force (Ft) and drag force (Fd) should occur: Ft-Fd = 0; hence the power generated by thrust forces (Pt = Ft·v) should be equal to the power needed to overcome drag forces at that speed (Pd = Fd·v); the aim of this study was to measure Pt (tethered swims), to estimate Pd in active conditions (at sprint speed) and to compare these values. 10 front crawl male elite swimmers (expertise: 93.1 ± 2.4% of 50 m world record) participated to the study; their sprint speed was measured during a 30 m maximal trial. Ft was assessed during a 15 s tethered effort; passive towing measurement were performed to determine speed specific drag in passive conditions (kP = passive drag force/v2); drag force in active conditions (Fd = kA·v2) was calculated assuming that kA = 1.5·kP. Average sprint speed was 2.20 ± 0.07 m·s-1; kA, at this speed, was 37.2 ± 2.7 N·s2·m-2. No significant differences (paired t-test: p > 0.8) were observed between Pt (399 ± 56 W) and Pd (400 ± 57 W) and a strong correlation (R = 0.95, p < 0.001) was observed between these two parameters. The Bland-Altman plot indicated a good agreement and a small, acceptable, error (bias: -0.89 W, limits of agreement: -25.5 and 23.7 W). Power thrust experiments can thus be suggested as a valid tool for estimating a swimmer's power propulsion.

Air Force Cyber Outreach

DTIC Science & Technology

2017-09-17

design process requires teams to analyze and organize information in a manner that communicates efficiently with stakeholders. This communication is...share information (with each other and local school districts) on available/applicable grants b. How to help school districts identify and/or...graphed below. The graph compares the advance’s relative impact on the ability of the Air Force to maintain 12 information and decision dominance (x

In Search of an Identity: Air Force Core Competencies

DTIC Science & Technology

1997-06-01

for connecting core competencies to both inside and outside the service . Core competencies have become a decision making framework for the Air Force...Proposed Intra– Service Relationship ................................................................. 76 Figure 2. Proposed Inter- service and Joint...connecting core competencies to both inside and outside the service . Core competencies have become a decision making framework for the Air Force. They

Preliminary Evaluation of the Effectiveness of Air Force Advertising.

ERIC Educational Resources Information Center

Vitola, Bart M.

The Airman Enlistment Questionnaire was administered to a sample of non prior service enlistees, 1,667 males and 300 females. Analysis of the responses shows (1)educational opportunity is the strongest motivator for enlisting in the Air Force; (2) there is an indication that Air Force advertising should make different appeals to men and women; and…

IS FREE REALLY FREE PALACE ACQUIRE AS AN EFFECTIVE FORCE RENEWAL SOURCE FOR AIR FORCE PUBLIC AFFAIRS

DTIC Science & Technology

2016-02-29

AU/ACSC/2016 AIR COMMAND AND STAFF COLLEGE AIR UNIVERSITY IS FREE REALLY FREE ? PALACE ACQUIRE AS AN EFFECTIVE FORCE RENEWAL SOURCE FOR AIR...transfer-eligible candidates, and external applicants. Ultimately, this research reveals, the cost – in both money and manpower – does not support...these employees provide to their sponsoring offices in “ free manning.” 5 CHAPTER 1 Introduction Public Affairs is key aspect of Air Force

[Professional psychological selection system in the Air Force - 50 years].

PubMed

Pokrovskiĭ, B L

2014-08-01

Given the data about the establishment of the professional psychological selection system in the Air Force in 1958-1964 in the NIIIAM Air Force by the team psychological department under the leadership of K.K.Platonova. Given the names of the developers of this system and given the results of their research. The result of all made work the order of Air Force Commander about the introduction of the psychological selection in Higher Military Aviation School of Pilots, starting from a set of 1964 became. Recommendations for professional psychological selection of a wide range of aviation professionals in various fields, and in the future - and other professionals of the Armed Forces, became the results of future work.

Overview of external Nacelle drag and interference drag

NASA Technical Reports Server (NTRS)

Neal, R. D.

1975-01-01

A historical view of multi-jet engine installations is given that emphasizes integration of the powerplant and the airframe in aircraft design for improved reduction in external nacelle drag and interference drag characteristics.

The United States Air Force Reserve Officer Training Corps: Looking to the Future

DTIC Science & Technology

1991-03-04

Brigadier General Robin G. Tornow Commandant, Air Force ROTC (Note 25) Over the years, Air Force ROTC has developed many strong points. Paramount among...maintaining a leaner and more capable force for the future. Brigadier General Robin G. Tornow Commandant, Air Force ROTC (Note 35) This alternative

32 CFR 865.5 - Decision of the Secretary of the Air Force.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 32 National Defense 6 2010-07-01 2010-07-01 false Decision of the Secretary of the Air Force. 865.5 Section 865.5 National Defense Department of Defense (Continued) DEPARTMENT OF THE AIR FORCE ORGANIZATION AND MISSION-GENERAL PERSONNEL REVIEW BOARDS Air Force Board for Correction of Military Records...

32 CFR 989.7 - Requests from Non-Air Force agencies or entities.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 32 National Defense 6 2010-07-01 2010-07-01 false Requests from Non-Air Force agencies or entities. 989.7 Section 989.7 National Defense Department of Defense (Continued) DEPARTMENT OF THE AIR FORCE ENVIRONMENTAL PROTECTION ENVIRONMENTAL IMPACT ANALYSIS PROCESS (EIAP) § 989.7 Requests from Non-Air Force...

Zero-Base Budgeting Impact on Air Force Laboratories.

DTIC Science & Technology

1980-08-01

discon- tinued. ZBB later surfaced, some think originated, at Texas Instruments, having been introduced by Peter Phyrr in 1968.21 Jimmy Carter, then...little more sense to some people and a little less to others. It just does not hang together as a presentation of agency policies. There are more...8217s the Air Force formed the Air Force Management Improvement Group to address people inter- actions and how they fit the future needs. The emphasis of

19. DETAIL OF AIR FORCE WEATHER INFORMATION TERMINAL AND CHART ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

19. DETAIL OF AIR FORCE WEATHER INFORMATION TERMINAL AND CHART RECORDER LOCATED IMMEDIATELY NORTH OF CONSOLE IN PHOTOS A-15 THROUGH A-18. - Vandenberg Air Force Base, Space Launch Complex 3, Launch Operations Building, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

An Analysis of Air Force Management of Turbine Engine Monitoring Systems (TEMS).

DTIC Science & Technology

1980-06-01

AIR FORCE AIR UNIVERSITY (ATC) C AIR FORCE INSTITUTE OF TECHNOLOGY LWright-Patterson Air Force Base, Ohio 80 9 22 057 All BBO RCE j GEMEM Elbert B...detrimental ideas, or deleterious information are contained therein. Furthermore, the views expressed in the document are those of the author(s) and...role problems, information flow and integration problems, and leadership and command problems. Four alternative management concepts were analyzed. Based

A Study of Black Officer Candidate Attrition in the United States Air Force

DTIC Science & Technology

1993-09-01

concern among Air Force accession policy officials (Travers, 1992). Prior to 1973 the Air Force, as well as all other services, was under -represented in...Although the Air Force did not exist in 1940, its predecessor, the Army Air Corps, fell under this new policy. Thus, by the time the Air Force was made a...participation increased from 0.6 percent in 1942 to approximately 2 percent by 1973. However, blacks were 3till vastly under -represented in relation to both the

Aerodynamic Efficiency Analysis on Modified Drag Generator of Tanker-Ship Using Symmetrical Airfoil

NASA Astrophysics Data System (ADS)

Moranova, Starida; Rahmat Hadiyatul A., S. T.; Indra Permana S., S. T.

2018-04-01

Time reduction of tanker ship spent in the sea should be applied for solving problems occured in oil and gas distribution, such as the unpunctuality of the distribution and oil spilling. The aerodynamic design for some parts that considered as drag generators is presumed to be one of the solution, utilizing our demand of the increasing speed. This paper suggests two examples of the more-aerodynamic design of a part in the tanker that is considered a drag generator, and reports the value of drag generated from the basic and the suggested aerodynamic designs. The new designs are made by adding the NACA airfoil to the cross section of the drag generator. The scenario is assumed with a 39 km/hour speed of tanker, neglecting the hydrodynamic effects occured in the tanker by cutting it at the waterline which separated the drag between air and water. The results of produced drag in each design are calculated by Computational Fluid Dynamic method.

Racializing white drag.

PubMed

Rhyne, Ragan

2004-01-01

While drag is primarily understood as a performance of gender, other performative categories such as race, class, and sexuality create drag meaning as well. Though other categories of identification are increasingly understood as essential elements of drag by performers of color, whiteness remains an unmarked category in the scholarship on drag performances by white queens. In this paper, I argue that drag by white queens must be understood as a performance of race as well as gender and that codes of gender excess are specifically constructed through the framework of these other axes of identity. This essay asks whether white performance by white queens necessarily reinscribes white supremacy through the performance of an unmarked white femininity, or might drag performance complicate (though not necessarily subvert) categories of race as well as gender? In this essay, I will suggest that camp drag performances, through the deployment of class as a crucial category of performative femininity, might indeed be a key site through which whiteness is denaturalized and its power challenged. Specifically, I will read on camp as a politicized mode of race, class and gender performance, focusing on the intersections of these categories of identity in the drag performance of Divine.

Environmental Assessment: Western Range Instrumentation Modernization Program Vandenberg Air Force Base, Santa Barbara County, and Pillar Point Air Force Station, San Mateo County California

DTIC Science & Technology

2008-09-03

Force Base ( AFB ), and Pillar Point Air Force Station (AFS), California. The 30th Space Wing at Vandenberg AFB operates the Western Launch and Test...Range (Western Range). The Western Range begins at the coastal boundaries of Vandenberg AFB and extends westward to the Marshall Islands, including...Vandenberg AFB . Vandenberg AFB is headquarters to the 30th Space Wing, the Air Force Space Command unit that operates Vandenberg AFB and the Western

Diversity Within the U.S. Air Force Senior Leadership

DTIC Science & Technology

2010-02-17

15 1 Introduction The United States Air Force is committed to equal opportunity and diversity within its ranks. According to...Office. Diversity and Equal Opportunity in Our Air Force. AFTV Video. 9 min., March 2009. 2 What is diversity and is it important? When...attributes reflect unchangeable human differences that are either inborn or developed in our early socialization . Secondary dimensions of diversity

A biomechanical comparison in the lower limb and lumbar spine between a hit and drag flick in field hockey.

PubMed

Ng, Leo; Rosalie, Simon M; Sherry, Dorianne; Loh, Wei Bing; Sjurseth, Andreas M; Iyengar, Shrikant; Wild, Catherine Y

2018-03-01

Research has revealed that field hockey drag flickers have greater odds of hip and lumbar injuries compared to non-drag flickers (DF). This study aimed to compare the biomechanics of a field hockey hit and a specialised field hockey drag flick. Eighteen male and seven female specialised hockey DF performed a hit and a drag flick in a motion analysis laboratory with an 18-camera three-dimensional motion analysis system and a calibrated multichannel force platform to examine differences in lower limb and lumbar kinematics and kinetics. Results revealed that drag flicks were performed with more of a forward lunge on the left lower limb resulting in significantly greater left ankle dorsiflexion, knee, hip and lumbar flexion (Ps<0.001) compared to a hit. Drag flicks were also performed with significantly greater lateral flexion (P < 0.002) and rotation of the lumbar spine (P < 0.006) compared to a hit. Differences in kinematics lead to greater shear, compression and tensile forces in multiple left lower limb and lumbar joints in the drag flick compared to the hit (P < 0.05). The biomechanical differences in drag flicks compared to a hit may have ramifications with respect to injury in field hockey drag flickers.

Air Force Smart Bases

DTIC Science & Technology

2017-10-19

the future. Then to design an information and data architecture to enable many use cases for further mission experimentation and acquisition strategy...development. A key feature of the future of smart cities (or, in our case , smart bases) is that citizen engagement with one another and with their...cybersecurity on Air Force installations. Participants The design sprint brought in over 30 participants from across the military and industry

Oversight of the Air Force - What is the Audit Component and How Can Air Force Managers Deal with It Effectively?

DTIC Science & Technology

1988-05-01

This report discusses authority, mission, and responsibilities of the audit organizations that perform oversight of Air Force operations. A...the discussion of the major audit organizations. The audit oversight function is here to stay. Auditors and audit organizations can be beneficial to Air

Air Force Roles and Missions: A History

DTIC Science & Technology

1998-01-01

armies fighting on the Western Front. In July, Foch gave Pershing tactical control of a sector in the Chateau- Thierry region, with only one division...In the battle at Chateau- Thierry in July, air squadrons flying support for the American division learned a costly lesson. Air units were deci- mated... Thierry , he saw Trenchard’s views on the need to concentrate air forces to achieve aerial superiority confirmed. The losses helped Mitchell convince

Summary of the Fourth AIAA CFD Drag Prediction Workshop