Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “WING”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,153 records · Page 64
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

The spanwise lift distribution on a wing from flow-field velocity surveys

The application of the incompressible three-dimensional momentum integral equation to a finite wing is reviewed. The objective is to interpret the resulting equations in a way that suggests an alternate experimental method for determining the span-wise distribution of lift. Consideration is given to constraints that must be placed on the character of the vortex wake of the wing to provide the familiar relationship between lift and bound vorticity. A novel technique is then presented for obtaining, from behind the wing, the spanwise lift distribution from velocity surveys that are made over only a short distance above and below the wing trailing edge. The necessary formalism is developed to use these measured values to obtain the actual span loading by using an equivalent single horseshoe vortex model to account for the unmeasured portion of the downward (or upward) momentum. The results of a numerical simulation are presented for a typical loading distribution. The technique is then verified experimentally using laser velocimeter data for the flow field around a model wing.

Orloff, K. L.↗
NASA NTRS1978

Theoretical and experimental aerodynamics of strake-wing interactions up to high angles-of-attack

This paper reports on an experimental investigation where the longitudinal aerodynamic characteristics were determined up to high angles-of-attack for configurations employing parametric variations in strake span and wing sweep and includes correlations with theory. The investigation included both component and complete configuration studies to provide information for the analysis of interaction effects. Comparisons between strake-wing and high canard-wing configurations demonstrate the strake-wing to develop higher lift coefficients than did the canard-wing due to enhanced interference effects. Correlations with theory demonstrate the suction analogy to be a useful method for estimating the effects of vortex flow aerodynamics on both component and total forces and moments.

Luckring, J. M.↗
NASA NTRS1978

Some observations on the mechanism of aircraft wing rock

A pressure scale model of Northrop F-5A was tested in NASA Ames Research Center Eleven-Foot Transonic Tunnel to simulate the wing rock oscillations in a transonic maneuver. For this purpose, a flexible model support device was designed and fabricated which allowed the model to oscillate in roll at the scaled wing rock frequency. Two tunnel entries were performed to acquire the pressure (steady state and fluctuating) and response data when the model was held fixed and when it was excited by flow to oscillate in roll. Based on these data, a limit cycle mechanism was identified which supplied energy to the aircraft model and caused the Dutch roll type oscillations, commonly called wing rock. The major origin of the fluctuating pressures which contributed to the limit cycle was traced to the wing surface leading edge stall and the subsequent lift recovery. For typical wing rock oscillations, the energy balance between the pressure work input and the energy consumed by the model aerodynamic and mechanical damping was formulated and numerical data presented.

Hwang, C.↗
NASA NTRS1978

A study on the utilization of advanced composites in commercial aircraft wing structure: Executive summary

The overall wing study objectives are to study and plan the effort by commercial transport aircraft manufacturers to accomplish the transition from current conventional materials and practices to extensive use of advanced composites in wings of aircraft that will enter service in the 1985-1990 time period. Specific wing study objectives are to define the technology and data needed to support an aircraft manufacturer's commitment to utilize composites primary wing structure in future production aircraft and to develop plans for a composite wing technology program which will provide the needed technology and data.

Watts, D. J.↗
NASA NTRS1979

Low-speed wind-tunnel investigation of wing fins as trailing-vortex-alleviation devices on a transport airplane model

The trailing-vortex-alleviation effectiveness of both a one- and a two-fin configuration (semicircular with a radius of 0.043 semispan) on a jumbo-jet transport airplane model in its landing configuration was investigated in the Langley V/STOL tunnel, by the trailing-wing sensor technique. The fins were located on the upper surface of the transport model wing along the 30-percent-chord line. The fin configurations were effective in reducing the vortex-induced rolling moment, by amounts varying from 28 to 60 percent, on the trailing wing model located at a distance of 7.8 transport model wing spans downstream of the transport model. The flow over the fins and over the transport airplane model wing downstream of the fins was observed to be separated and turbulent. All fin configurations caused a reduction in maximum lift coefficient, a positive increment in drag coefficient, and an increment in nose-up pitching-moment coefficient on the transport airplane model.

Croom, D. R.↗
NASA NTRS1979

The effect of canard relative size and vertical location on the subsonic longitudinal and lateral-directional static aerodynamic characteristics for a model with a swept forward wing

A general research fighter model was tested in the Langley 7- by 10-foot high speed tunnel at a Mach number of 0.3. The model was tested with a 32 deg swept forward wing mounted in mid-, low-, and high-wing positions. For the mid-wing configuration, the model was tested with a 51.7 deg swept back canard mounted in mid-, low-, and high-canard positions. For the mid-wing mid-canard and the mid-wing high-canard configurations, canards of similar planform having two different areas were tested. The angle-of-attack range was from approximately -4 deg to 48 deg at sideslip angles of 0 deg, -5 deg, and 5 deg.

Huffman, J. K.↗
NASA NTRS1979

Flow visualization studies of a general research fighter model employing a strake-wing concept at subsonic speeds

A systematic wind tunnel study was conducted in the Langley high-speed 7 by 10 foot tunnel to document, by oil-flow photographs, the surface flow patterns for configurations incorporating strake-wing geometries indicative of current and proposed maneuvering aircraft. The configurations employed combinations of strakes with reflexed planforms having exposed spans of 10 percent, 20 percent, and 30 percent of the reference wing span and wings with trapezoidal planforms having leading-edge sweep angles of approximately 30 deg, 44 deg, and 60 deg. Tests were conducted at Mach numbers of 0.3 and 0.5 and at angles of attack ranging from approximately 5 deg to 30 deg in 5 deg increments at 0 deg sideslip. The configurations incorporating the strake-wing geometries exhibited more organized flow patterns with smaller asymmetries to higher angles of attack than the corresponding configurations incorporating the wing-alone geometries did.

Luckring, J. M.↗
NASA NTRS1979

Powered low-aspect-ratio Wing In Ground effect (WIG) aerodynamic characteristics

A wing-in-ground effect configuration was investigated. The configuration used large diameter, low pressure ratio fans mounted about 0.76 wing chord ahead of the wing leading edge to achieve a power augmented ram wing during operation in ground effect. Tests of both in and out of ground effect aerodynamic transition characteristics from very low speeds to cruise speeds are described. The investigation provided a number of conclusions concerning the aerodynamic/propulsive performance interaction. While power augmented lift is required for low speed flight, there is a thrust loss when the efflux is trapped under the wing which reduced the effective thrust to weight available for acceleration by about a third of the installed thrust to weight ratio.

Thomas, J. L.↗
NASA NTRS1979

Some observations on the mechanism of aircraft wing rock

A scale model of the Northrop F-5A was tested in NASA Ames Research Center Eleven-Foot Transonic Tunnel to simulate the wing rock oscillations in a transonic maneuver. For this purpose, a flexible model support device was designed and fabricated, which allowed the model to oscillate in roll at the scaled wing rock frequency. Two tunnel entries were performed to acquire the pressure (steady state and fluctuating) and response data when the model was held fixed and when it was excited by flow to oscillate in roll. Based on these data, a limit cycle mechanism was identified, which supplied energy to the aircraft model and caused the Dutch roll type oscillations, commonly called wing rock. The major origin of the fluctuating pressures that contributed to the limit cycle was traced to the wing surface leading edge stall and the subsequent lift recovery. For typical wing rock oscillations, the energy balance between the pressure work input and the energy consumed by the model's aerodynamic and mechanical damping was formulated and numerical data presented.

Hwang, C.↗
NASA NTRS1979

Transonic aerodynamic characteristics of a supersonic cruise aircraft research model with the engines suspended above the wing

The influence of upper-surface nacelle exhaust flow on the aerodynamic characteristics of a supersonic cruise aircraft research configuration was investigated in a 16 foot transonic tunnel over a range of Mach numbers from 0.60 to 1.20. The arrow-wing transport configuration with engines suspended over the wing was tested at angles of attack from -4 deg to 6 deg and jet total pressure ratios from 1 to approximately 13. Wing-tip leading edge flap deflections of -10 deg to 10 deg were tested with the wing-body configuration. Various nacelle locations (chordwise, spanwise, and vertical) were tested over the ranges of Mach numbers, angles of attack, and jet total-pressure ratios. The results show that reflecting the wing-tip leading edge flap from 0 deg to -10 deg increased the maximum lift-drag ratio by 1.0 at subsonic speeds. Jet exhaust interference effects were negligible.

Mercer, C. E.↗
NASA NTRS1979

Theoretical study of aerodynamic characteristics of wings having vortex flow

The aerodynamic characteristics of slender wings having separation induced vortex flows are investigated by employing three different computer codes--free vortex sheet, quasi vortex lattice, and suction analogy methods. Their capabilities and limitations are examined, and modifications are discussed. Flat wings of different configurations: arrow, delta, and diamond shapes, as well as cambered delta wings, are studied. The effect of notch ratio on the load distributions and the longitudinal characteristics of a family of arrow and diamond wings is explored. The sectional lift coefficients and the accumulated span loadings are determined for an arrow wing and are seen to be unusual in comparison with the attached flow results. The theoretically predicted results are compared with the existing experimental values.

Reddy, C. S.↗
NASA NTRS1980

Effect of a flexibly mounted store on the flutter speed of a wing

A passive system proposed for increasing the flutter speed of a wing with heavy concentrated weights involves the concept of mounting the store on a pitch pivot having a very low pitch stiffness relative to the wing stiffness. This concept was investigated utilizing a two dimensional approach involving 4 degrees of freedom, namely, wing bending, wing torsion, store pitch and store vertical translation. This preliminary analysis was very encouraging and the results demonstrate that, if the uncoupled store pitch frequency was below the wing bending frequency, the flutter speed was greatly increased. A second more complete analysis was developed utilizing a three dimensional structure, but retaining the two dimensional, incompressible unsteady airforces of Theodorsen. The details of the analysis are included.

Runyan, H. L.↗
NASA NTRS1980

Development of the Learjet 28/29 Wing Using NASTRAN Analysis

The structural development work performed on the Learjet 28/29 wing using NASTRAN analysis is discussed. The work included the basic sizing of primary structural members such as wing skins, wing skin splices, and spar caps, as well as the calculation of preliminary weight estimates utilizing the weight computation routine in NASTRAN. The eight spar redundancy of the Learjet wing made this task somewhat more complex than for more determinate type wing structures. Some of the problems that were encountered and the solutions and methods that were used are described.

Boroughs, R. R.↗
NASA NTRS1980

Works on theory of flapping wing

It is shown mathematically that taking account of the boundary layer is the only way to develop a theory of flapping wings without violating the basic observations and mathematics of hydromechanics. A theory of thrust generation by flapping wings can be developed if the conventional downstream velocity discontinuity surface is replaced with the observed Karman type vortex streets behind a flapping wing. Experiments show that the direction of such vortices is the reverse of that of conventional Karman streets. The streets form by breakdown of the boundary layer. Detailed analysis of the movements of certain birds and insects during flight 'in place' is fully consistent with this theory of the lift, thrust and drag of flapping wings. Further directions for research into flight with flapping wings are indicated.

Golubev, V. V.↗
NASA NTRS1980

The effects of leading edge modifications on the post-stall characteristics of wings

An investigation of the effects of leading edge modifications on the post-stall characteristics of two rectangular planform wings in a series of low speed wind tunnel tests is presented. Abrupt discontinuities in the leading edge shape of the wings were produced by placing a nose glove over a portion of the span or by deflecting sections of a segmented leading edge flap. Six component balance data, oil flow visualization photographs, and pressure distribution measurements were obtained, and tests made to study the development of flow separation at stall on small scale planform wing models. Results of oil flow visualization tests at and beyond stall showed the formation of counter-rotating swirl patterns on the upper surface of the '2-D' and '3-D' wings, and results of a numerical lifting line technique applied to wings with leading edge modifications are included.

Winkelmann, A. E.↗
NASA NTRS1980

Performance improvement of delta wings at subsonic speeds due to vortex flaps

Subsonic wind tunnel tests were conducted to determine performance improvements possible from the use of leading edge vortex flaps (LEVF) on delta wings. Various flap sizes and deflection angles were examined and lift-to-drag ratio improvements of up to 40% were found at moderate angles of attack on 60 deg and 75 deg swept wings. The LEVF is concluded to be effective in moving the wing's leading edge vortex onto the flaps, tilting the vortex-induced force vector forward to produce a thrust or reduce the wing's drag while maintaining attached flow and lift on the wing's upper surface.

Marchman, J. F., III↗
NASA NTRS1980

Controlled supercritical crossflow on supersonic wings - An experimental validation

Leading edges of wings with high lift at supersonic speeds are discussed. Under these conditions, the leading edge must generate a controlled supercritical crossflow such that high lift is obtained without boundary layer separation. The leading edge concept that accomplishes this is the supersonic counterpart of the leading edge of the 2-D supercritical airfoil at transonic speeds. Wind tunnel test results on a cambered wing with a controlled supercritical crossflow leading edge successfully validated the concept. The main results are presented at the M = 1.62 design point, with off-design results given for the range of Mach numbers from 1.60 to 2.00. Surface pressure, oil flow photographs, and force data are presented and analyzed. A flat wing with the same thickness distribution was also tested and the results were used both for comparison with the designed wing and to illustrate the development of the supercritical crossflow region which, for the flat wing, is terminated by a distinct crossflow shock wave.

Mason, W. H.↗
NASA NTRS1980

Higher order farfield drag minimization for a subcritical wing design code

A higher order Trefftz plane model of the undistorted interacting wing wakes of two symmetric subsonic planforms has been developed and integrated with an existing vortex lattice wing design code. The Trefftz plane calculation provides continuous, piecewise quadratically varying bound circulations, which are then interpolated in the nearfield vortex lattice representation of the wing. Integration of the surface slopes for a specified chord loading function provides the design wing camber surfaces. This paper outlines the theoretical development and presents comparisons between results obtained using the present theory and (1) previous exact solutions for minimum induced drag and (2) previous wing designs obtained using a discrete vortex wake moded.

Kuhlman, J. M.↗