... F/A-18C TO E WING MORPHING STUDY ... 4. TITLE AND SUBTITLE F/A-18C to E Wing Morphing Study for the Abrupt Wing Stall Program 5a. ...
DTIC Science & Technology
Aug 9, 2011 ... To provide a cheap capability for flow visualization over complex ... 2001 and April 2002 as part of the Abrupt Wing Stall Program. ...
NASA Website
... Title : Tapered Wings, Tip Stalling, and Preliminary Results from ... STALLING, AERODYNAMIC CHARACTERISTICS, WING TIPS, TAPER, WINGS ...
As part of the NASA/Navy Abrupt Wing Stall Program, a relatively low-cost, rapid-access wind-tunnel free-to-roll rig was developed. This rig combines the use of conventional models and test apparatuses to evaluate both transonic performance and wing-drop/...
National Technical Information Service (NTIS)
Wind tunnel tests to determine the flow characteristics of a stalled wing are described. The advantages of the plane wing over the ring wing for wind tunnel investigations are presented. The general flow pattern for stalled ring airfoils is developed. Pho...
... Accession Number : ADA203077. Title : Stall Flutter of Graphite/Epoxy Wings with Bending-Torsion Coupling. Descriptive ...
... have shown the variety of the forms of a vortex flow with the stall on straight wings. ... large-scale pair vortexes rotating in planes of a wing and the ...
Cruise Linear Reynolds Number. 577095 per ft. Cruise Wing Reynolds Number. 1264800. Stall Linear Reynolds Number. 322386 per ft. Stall Wing Reynolds Number ...
The abrupt wing stall (AWS) program was a 5-year program that addressed the problem of uncommanded, transonic lateral motions, such as wing drop, with experimental, computational, and simulation tools. A brief background is presented as are the motivations and objectives for the AWS program. Since the ...
NASA Astrophysics Data System (ADS)
... The wing stall path has been analyzed through flow visualization with tufts on wing upper surface. ... 29 flow visualization on wing upper surface at ...
... Title : Investigation of High-Lift and Stall-Control Devices on an NACA 64-Series 42 deg Sweptback Wing with and Without Fuselage. ...
Page 1. NONLINEAR STALL FLUTTER OF WINGS WITH BENDING-TORSION COUPLING MU~IR--iv 9Z~ Wi!.1Report tar Per,.od: 2 F'ebruary 1991 ...
A laser velocimeter operating in the backscatter mode was used to survey the flow about a stalled wing installed in the Langley V/STOL tunnel. Mean velocities and magnitudes of velocity fluctuations were calculated from measurements of two orthogonal comp...
... STEADY STATE, AIRCRAFT, THESES, STALLING, VERTICAL ORIENTATION, COEFFICIENTS, WINGS, AILERONS, MOMENT OF INERTIA. ...
... warning mechanism. ... experiencing leading edge stall cause a negative damping in ... so that effective feedback mechanisms can be developed to ...
... transients to fully stalled wings, providing substantial ... position of the wing such that ... Flow visualization using marking techniques such as timelines ...
... trolled rolling dive, that results from a sudden loss of lift on the right or left wing and u simultaneous loss of lateral control. ...
... ON AN NACA 64-SERIES 42° SWEPTBACK WING WITH AND'WITHOUT FUSELAGE By ... F#uw £.- Geometry of 42° swept-bock wing and fuseloge. ...
... both straight and swept planform flow visualization tests were ... model of the modified wing flow field ... downstream over the wing surface and influence ...
... flow were visible on the wing upper surface until a ... stall starts at 2/3 of the wing span exactly as ... shows an example of the oil flow visualization in the ...
... drag and pitching moment coefficients Bffact of aealing gaps between main wing and tip«. Variable incidence tips set at 0 . Flaps 60° , Elevons -10° ...
A computational study was conducted to explain the aerodynamic effect of leading edge tubercles on maximum lift coefficient, stall angle of attack (AoA), drag, and post stall characteristics for airfoils as well as finite wings. Past experiments demonstrated airfoils with leading edge tubercles do not improve Clmax, drag, or ...
...abruptly pushes the nose down at a selected angle of attack (e.g., a stick pusher...at the stall speed; (2) Propeller pitch controls (if applicable) in the takeoff...abruptly pushes the nose down at a selected angle of attack (e.g., a stick...
Code of Federal Regulations, 2010
A low speed wind tunnel experimental investigation was conducted to determine the effectiveness of the leading edge pulsed blowing and the trailing edge jet blowing/ Gurney flap on the improvement of aerodynamic performance of an unmanned aerial vehicle at low Reynolds numbers. The wind tunnel tests for the leading edge pulsed jet blowing were conducted at 10%, 30% and 50% location of the chord ...
E-print Network
characteristics. Loss of aircraft control, where structural ice accretion has been identified as a probable cause effectiveness and aircraft roll and controllability during stall. Recall for a finite wing with an elliptic alter the wing's stall pattern and the pilots ability to control the aircraft during ...
The purpose was to develop a bank of aerodynamic data including high angle-of-attack aerodynamic characteristics of 2-D airfoils and characteristics of 3-D wings and of complete airplanes beyond the stall. To fill gaps in available literature, flow visual...
The purpose of this project was to develop a bank of aerodynamic data including high angle-of-attack aerodynamic characteristics of 2-d airfoils and characteristics of 3-D wings and of complete airplanes beyond the stall. To fill gaps in available literat...
The nonlinear, stalled, aeroelastic behavior of rectangular. graphite/epoxy, cantilevered plates with varying amounts of bending-torsion stiffness coupling and with NACA 0012 Styrofoam airfoil shapes is investigated for low Reynolds number flow (
Minimum flying speed for straight and level night occurs when the wing is operating at CL,max, that is, near the stall angle. The maximum flying speed for ...
... different. The center of lift is shifted toward the wingtip. The ... Ref. 4) created by the vortex suction lift of the wing tip vortex. Figure ...
... Freymuth3 provides excellent flow visualization pictures ... others have measured 1 the surface pressure ... related to fixed wing aircraft supermaneuvera ...
... position sensor detector (PSD) is used in conjunction acquisition process. ... Photonics 2LI 0-2 Duo-Lateral two-dimensional PSD is ...
Mar 30, 2010 ... This analysis is performed for ideal flow conditions and can not predict the wing stall which may occur for higher angles of attack. ...
... at high Reynolds numbers and low Mach numbers to determine the maximum-lift and stalling characteristics of an aspect-ratio-4 trapezoidal wing ...
... fuselage on the aero- dynamic characteristics of ... edge back 10.- Aerodynamic- center location ... EFEKENCEt Wings - Aerodynamics (99150); Control ...
... Descriptors : *SWEPTBACK WINGS, AERODYNAMIC CONTROL SURFACES, AERODYNAMIC FORCES, FLAPS(CONTROL SURFACES). ...
... inaiijht into the stalling characteristics of a wing can be obtain' d by considering the growth of the boundary layer at hi{.;li incidences (Hef.7). A ...
Information on the stalling characteristics, static longitudinal stability .... Abstract: Loads imposed upon the Bell X-5 and Douglas D-558-II swept-wing ...
ators themselves contribute to blade overall stiffness ...... Datta, A., and Chopra, I., Prediction of UH-. 60A Dynamic Stall Loads in High Altitude Level ...
... alternating LE and TE stall vortices, which did ... 18. Strawn, R. C.. "Wing Tip Vortex Calculations with an ... Chow, J., "A Computational Study of Wingtip ...
... emphasis on the lift curve slope and stall behavior. ... The most notable being the Ryan XV-5a which employed a jet powered wing lifting fan (see ...
... At low horizontal velocities, this lip stall would probably limit the rate of descent of a vehicle with a wing-tip-mounted ducted fan. ...
TM 1347, 1953. Furlong, G. Chester and Fitzpatrick, James E.: Effects of. Mach Number and Reynolds Number on the Maximum Lift ...
The occurrence of vortex breakdown on a swept wing at high angle-of- attack is a well-known phenomenon. It has important consequences for the unsteady loading of the wing surface, as well as the surface of an aerodynamic appendage, the most prevalent form...
Jan 1, 1979 ... A laser velocimeter (LV) surveyed the flow above two stalled wings. ... Each wing was tested in a different wind tunnel at different Mach numbers. ... FLOW MEASUREMENT; FLOW VELOCITY; FLOW VISUALIZATION; ...
The present paper reports a study on the dynamic behaviour of a compression system based on a multi-stage centrifugal blower and provided with a device for the active suppression of surge instability. The control device includes a sensor of total pressure...
Force measurement and surface oil flow visualization experiments were conducted in a wind tunnel to investigate the effects of flexibility on aerodynamic performance of delta wings with different sweep angles. The experimental results indicate that the maximum lift coefficient is increased and the stall angle is delayed as the sweep angle increases for ...
wing beyond stall, again focusing on the surface streaklines in oil flow visualization. Weihs and Katz three-dimensional flow patterns on airfoils. They based their observations on surface visualization-dimensional separation over a yawed or straight rotating wing with high radial acceleration at the surface. High aspect
Index TermsVector field visualization, vector field topology, flow visualizaiton, .... delta wing aircraft where the airflow abruptly leaves and then returns to ...
angle of attack at the wing tip than at the root, known as washout. This leads to smaller induced drag and also prevents the wing-tip from stalling first, which can be undesirable from stability point of view in figure (2): segment AB starting from root section and ending at the wing tip, and the other segment BC
for the depth of the wing structural box in the weight model, and including constraints on stall speed with winglets. C-wings are found to be a reasonable design alternative for tailless aircraft with requirements for planar wings, highlighting some of the modifications to the structural weight model. Next, we ...
Wing-leading-edge modifications included leading-edge droop and slat configurations having full-span, partial-span, or segmented arrangements. Other devices included wing-chord extensions, fences, and leading-edge stall strips. Good correlation was appare...
decreases as you move to the wing tip Incidence: Angle between the longitudinal axis and the wing chord lateral axis (helps prevent tip stall by changing angle of attack) Anhedral: Downward bend in wing (helps by altering the Angle of Attack Ailerons: horizontal surfaces located on wing tips ...
One of the most critical technical issues with regard to supersonic commercial transportation is the sonic boom that occurs during supersonic cruising flight, which causes impulsive noise on the ground. The �supersonic biplane theory� has been proposed to reduce the sonic boom. Shock wave interaction and cancellation between the wings of a supersonic biplane can be ...
Dynamic stall is a complex unsteady flow phenomenon that produced detrimental effects in many aeronautical applications. The most common one in which dynamic stall occurs is found on the retreating blade of a helicopter rotor in forward flight. The dynamic stall prediction and the associated pre and post aerodynamic loads is critical ...
Near-surface flow patterns along a basic delta wing of moderate sweep angle, representative of key features of Unmanned Combat Air Vehicles (UCAVs) and Micro Air Vehicles (MAVs), are visualized by a technique of high-image-density digital particle image velocimetry (DPIV), which provides quantitative representations of the whole-field flow patterns. Due to the highly ...
The lift and thrust associated with insect flight strongly depend on the complex wake patterns produced by wing-wing and wing-wake interactions. We propose to investigate the aerodynamics of dragonfly using a simplified wing-wing model from the perspective of many-body force decomposition (JFM 600, p95) and the associated force ...
The wings of birds and insects often create an unsteady flow by their flapping and dynamic stall is used actively for landing or in low-speed flight. The flapping motion of the wings of insects consists of a combination of heaving (vertical movement in a ...
Results are presented of an investigation in the Langley 19-foot pressure tunnel of the longitudinal
NASA Technical Reports Server (NTRS)
This user's manual provides details on the Darrieus wind turbine aerodynamic performance/loads prediction computer code, VDART2. The code is the latest generation of vortex-based models and includes the effects of dynamic stall, pitching circulation, and ...
... 6. Newsom, Jr., William A., Satran, Dale R., and Johnson, Jr., Joesph L., Effects 2r Wing-Leading-Edge Modifications on a Full-Sa~l. Lo-ing Geea ...
... o to 60 o ) and just before the stall, large self-induced rolls ... drove the rolling motion. At the mean roll angle, because of the time lag in the strength of ...
Experimental studies were conducted to assess Reynolds and Mach number effects on a supercritical multielement airfoil. The airfoil is representative of the stall-critical station of an advanced transport wing design. The experimental work was conducted a...
... flow control mechanisms, such as stall strips, vortex generators, and ... 8,9, and 10; centerline pylons; wingtip launchers; nacelle ... wing tip environment ...
Aug 14, 2009 ... In some wind tunnel tests, flow visualization techniques are used to ... Tufts and surface oil flow are used to provide information about the state of the ... Boundary layer separation is a souce of drag and the cause of wing stalls. ...
...factor normal to the flight path at VCL MAX W = Airplane gross weight; S = Aerodynamic reference wing area; and q = Dynamic pressure. (b) VCL MAX is determined with: (1) Engines idling, or, if that resultant thrust causes an...
Code of Federal Regulations, 2011
14 Aeronautics and Space 1 2011-01-01 2011-01-01...23.201 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION...above the stall speed, the elevator control must be pulled back...stop. (c) Normal use of elevator control for recovery...
Conceptual wing design analysis methods are combined with numerical optimization to find minimum-drag wings subject to constraints on lift, weight, pitching moment, and stall speed. Tip extensions and winglets designed for minimum drag achieve similar performance, with the optimal solution depending on the ratio of the maneuver lift ...
In this report we calculated the effects of flow nonuniformities (wing shear, tower wake, yaw, and large-scale turbulence) on the performance of a horizontal axis wind turbine, accounting for dynamic stall. We modified the PROP program to incorporate and compare these effects with the uniform flow case. The MIT model, which predicts dynamic lift ...
Energy Citations Database
Dynamic stability and stall during steady level turns were examined for VA-1, a joined-wing flight demonstrator aircraft. Configurations with a lower vertical tail and fairings over the main landing gear were compared with a recommendation on the combinat...
-72. 34 Liiva, J. "Unsteady Aerodynamic and Stall Effects on Helicopter Rotor Blade Airfoil Sections". J aspect ratio wings and flap at a Strouhal number in the range from 0.2 to 0.46 , which suggests and Shyy and Liu9 for three-dimensional cases, the fluid physics associated with the flapping wing
The properties of actin network growth against a flat obstacle are studied using several different sets of molecular-level assumptions regarding filament growth and nucleation. These assumptions are incorporated into a multifilament methodology which treats both the distribution of filament orientations and bending of filaments. Three single-filament force-generation mechanisms in the literature ...
PubMed
The properties of actin network growth against a flat obstacle are studied using several different sets of molecular-level assumptions regarding filament growth and nucleation. These assumptions are incorporated into a multi-filament methodology which treats both the distribution of filament orientations and bending of filaments. Three single-filament force-generation mechanisms in the literature ...
PubMed Central
The development and shedding of leading edge vortices (LEVs) over wings is crucial to lift generation in the flapping flight of birds and insects. Many studies have investigated the flow field empirically by means of wing models that approximate or reproduce the wing kinematics. Wing models are often made of stiff ...
Over the past decade, the importance of unsteady aerodynamic mechanisms for flapping insect flight has become widely recognised. Even at the fastest flight speeds, the old quasi-steady aerodynamic interpretation seems inadequate to explain the extra lift produced by the wings. Recent experiments on rigid model wings have confirmed the effectiveness of ...
NREL has completed the initial twisted blade field tests of the ``Unsteady Aerodynamics Experiment.`` This test series continues systematic measurements of unsteady aerodynamic phenomena prevalent in stall-controlled horizontal axis wind turbines (HAWTs). The blade twist distribution optimizes power production at a single angle of attack along the span. ...
DOE Information Bridge
Here we analyse aeroelastic devices in the wings of a steppe eagle Aquila nipalensis during manoeuvres. Chaotic deflections of the upperwing coverts observed using video cameras carried by the bird (50 frames s(-1)) indicate trailing-edge separation but attached flow near the leading edge during flapping and gust response, and completely stalled flows upon ...
Here, we present a detailed analysis of the deforming wing kinematics of free-flying hoverflies (Eristalis tenax, Linnaeus) during hovering flight. We used four high-speed digital video cameras to reconstruct the motion of approximately 22 points on each wing using photogrammetric techniques. While the root-flapping motion of the wing ...
The aerodynamic forces acting on a revolving dried pigeon wing and a flat card replica were measured with a propeller rig, effectively simulating a wing in continual downstroke. Two methods were adopted: direct measurement of the reaction vertical force and torque via a forceplate, and a map of the pressures along and across the wing ...
The 1303 Unmanned Combat Air Vehicle is representative of a variety of UCAVs with blended wing-body configurations. Flow structure along a scale model of this configuration was investigated using dye visualization and particle image velocimetry for variations of Reynolds number and angle-of-attack. Both of these parameters substantially influence onset and structure of the ...
We report on experiments concerning unsteady effects in flapping flight, conducted in the low-speed wind tunnel of the TU Darmstadt using a mechanical flapping-wing model. Particle Image Velocimetry (PIV) was used for qualitative and quantitative analysis parallel and perpendicular to the flow field. A sensitivity analysis of the main flight parameters has been performed, with ...
Wind turbines are subjected to dynamic loading from a variety of different sources. Wind shear and turbulence cause time-varying inflow that results in unsteady airloads. Tower shadow, upwind turbine wakes, and yaw angles also introduce unsteady inflow to wind turbine rotors. Wind turbine designers must predict these loads accurately in order to adequately design blades, hubs, and the remaining ...
This report presents aerodynamic data on an NACA 0018 airfoil oscillating in pitch in the NAE 2m X 3m Low Speed Tunnel. The purpose of the test was to simulate the dynamic aerodynamic behavior of a Vertical Axis Wind Turbine blade section at the equatoria...
This user's manual provides details on the Darrieus wind turbine aerodynamic performance/loads prediction computer code, VDART2. The code is the latest generation of vortex-based models and includes the effects of dynamic stall, pitching circulation, and added mass.
...The stalling speeds VSO and VS1 with the landing gear and wing flaps retracted, determined at maximum weight under § 23...airplanes of more than 6,000 pounds maximum weight and multiengine turbine powered airplanes, the one-engine-inoperative takeoff...
Few mechanisms exist in nature that effect colour reflectivity, simultaneously high in spectral purity and in intensity, over a strictly limited portion of solid angle above a surface. Fewer still bring about such colour reflectivity with an angle dependence that is distinct from the colour transition associated with conventional multilayer interference. We have discovered that the ventral ...
This work presents a treatment of the helicopter vibration reduction problem at high advance ratios, taking into account the effects of dynamic stall. Dynamic stall is associated with separation of the airflow in the leading cadge region of the blade, which results in a lift coefficient overshoot, large pitching moments, and a drag penalty. Under separated ...
