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At least 109 records · Page 6

Theoretical lift due to wing incidence of slender wing-body-tail combinations at zero angle of attack

The theoretical lift of a cylindrical afterbody at zero angle of attack due to incidence of the wing is calculated by means of slender-body theory. It is assumed that the vortex sheet becomes fully rolled up ahead of the tail, and the vortex paths in the presence of the body are determined analytically. The total lift of a variety of slender wing-body-tail combinations due to wing incidence is also calculated.

LOADS - FUSELAGE, NACELLES, AND CANOPIES↗

Relaxation methods for transonic flow about wing-cylinder combinations and lifting swept wings

The mixed elliptic-hyperbolic relaxation method for obtaining steady-state solutions to two-dimensional transonic potential equations is extended to the transonic small disturbance equation in three dimensions. In particular, transonic flow is considered both about nonlifting wing-cylinder combinations and over thin lifting wings with sweep and taper. The treatment is restricted to freestream Mach numbers less than one and to wings with subsonic trailing edges.

Bailey, F. R.↗

Transonic pressure measurements and comparison of theory to experiment for an arrow-wing configuration. Volume 1: Experimental data report, base configuration and effects of wing twist and leading-edge configuration

A wind tunnel test of an arrow-wing-body configuration consisting of flat and twisted wings, as well as a variety of leading- and trailing-edge control surface deflections, was conducted at Mach numbers from 0.4 to 1.1 to provide an experimental pressure data base for comparison with theoretical methods. Theory-to-experiment comparisons of detailed pressure distributions were made using current state-of-the-art attached and separated flow methods. The purpose of these comparisons was to delineate conditions under which these theories are valid for both flat and twisted wings and to explore the use of empirical methods to correct the theoretical methods where theory is deficient.

Manro, M. E.↗

Low-speed wind-tunnel investigation of a large-scale advanced arrow wing supersonic transport configuration with engines mounted above the wing for upper-surface blowing

The Langley full scale tunnel was used to investigate the low speed stability and control of an advanced arrow wing supersonic transport with engines mounted above the wing for upper-surface blowing. Tests were made over an angle of attack range of -10 to 32 deg, slideslip angles of + or -5 deg and a Reynolds number ranging from 3.53 million to 7.33 million (referenced to mean aerodynamic chord of the wing). Configuration variables included trailing-edge flap deflection, engine jet nozzle angle, engine thrust coefficient, engine out operation, and asymmetrical trailing-edge BLC for providing roll trim. Downwash measurements at the tail were obtained for different thrust coefficients, tail heights, and at two fuselage stations.

Shivers, J. P.↗

Over-the-Wing Propeller Reduces Wing Drag

Airflow favorably altered if propeller placed above and behind wing. Relocating propeller induces flow over wing airfoil leading edge, which produces leading-edge suction forces not usually attainable by wing in free-stream flow. Concept reduced drag significantly on aircraft model in 12-foot (3.7-meter) wind tunnel. Relocation also helps to reduce cabin noise.

Johnson, J. L., Jr.↗

In-flight measurements of wing ice shapes and wing section drag increases caused by natural icing conditions

Aircraft icing flight research was performed in natural icing conditions with a twin engine computer type STOL aircraft. In-flight measurements were made of the icing cloud environment, the shape of the ice accretion on the wing, and the corresponding increase in the wing section drag. Results are presented for three icing encounters. On one flight, the wing section drag coefficient increased 35 percent over the uniced baseline for cruise conditions while a 43 percent increase was observed at an aircraft angle of attack of 6.2 degrees.

Mikkelsen, K.↗

Conical Euler simulation of wing rock for a delta wing planform

Unsteady, vortex-dominated flowfields are presently studied by using the conical Euler equations as an efficient first step toward investigation of the full three-dimensional problem, under the assumption that the supersonic flow about a delta wing is conical and therefore allows the three-dimensional problem to be reduced to a two-dimensional one. Attention is given to the case of a delta wing undergoing wing-rock motion. The code developed has also been modified to allow treatment of the 'free-to-roll' case.

Lee, Elizabeth M.↗

A discrete vortex model for predicting wing rock of slender wings

The fluid mechanism responsible for generating wing rock of slender sharp-edged delta wings was investigated using an unsteady discrete vortex model developed for that purpose, which is based on results of experimental investigations. Combined experimental and computational results indicate that wing rock is sustained by a lag in the position of the leading edge vortices normal to the surface. Results of comutations also indicate that certain complex aerodynamic problems may be governed primarily by unsteady inviscid phenomena.

Arena, Andrew S., Jr.↗

Active control of wing rock of a delta wing at post-stall using tangential leading edge blowing

Post-stall roll control utilizing tangential leading edge blowing is demonstrated in a wind tunnel on a delta wing model that exhibited wing rock. The dampening effect of symmetric blowing alone on wing rock is found to be effective up to a certain maximum amount of blowing. A moderate amount of symmetric blowing was shown to be effective in linearizing the asymmetric blowing static rolling moment responses.

Wong, G. S.↗

Investigation of Minimum Drag and Maximum Lift-drag Ratios of Several Wing-body Combinations Including a Cambered Triangular Wing at Low Reynolds Numbers and at Supersonic Speeds

Theoretical and experimental data for wing-body combinations with wings of triangular, arrow, and diamond plan form are presented for Mach numbers of 1.62, 1.93, and 2.41 and a Reynolds number range of 1.4 x 10 to the 6th power to 0.7 x 10 to the 6th power. Included are two each of triangular and arrow plan-form wings cambered for approximately uniform load at m = 1.62 and lift coefficients of 0.08 and 0.20. Liquid-film studies of the flow over the various configurations are also presented.

Brown, Clinton E↗

Pressure Distribution on Joukowski Wings and Graphic Construction of Joukowski Wings

In the first article, in connection with a lecture on the hydrodynamic basis of flight and the potential flow about a Joukowski wing, the pressure distribution on several wings is computed and plotted. The diagrams of the pressure distributions are presented accompanied with a qualitative discussion of the pressure distribution. In the second article, the the cross-sectional outline (or profile) a Joukowski wing are plotted.

PRESSURE DISTRIBUTION - AIRFOILS - JOUKOWSKI↗

Tests of Nacelle-Propeller Combinations in Various Positions with Reference to Wings II : Thick Wing - Various Radial-Engine Cowlings - Tractor Propeller

This report is the second of a series giving the results obtained in the 20-foot wind tunnel of the National Advisory Committee for Aeronautics on the interference drag and propulsive efficiency of nacelle-propeller-wing combinations. The first report gave the results of the test of a N.A.C.A. cowled air-cooled engine nacelle located in 21 positions with reference to a thick wing. The present report gives results of tests of a normal engine nacelle with several types of cowling and fairings in four of the positions with reference to the same wing. (author)

Wood, Donald H↗

Supersonic wing and wing-body shape optimization using an adjoint formulation

This paper describes the implementation of optimization techniques based on control theory for wing and wing-body design of supersonic configurations. The work represents an extension of our earlier research in which control theory is used to devise a design procedure that significantly reduces the computational cost by employing an adjoint equation. In previous studies it was shown that control theory could be used to~eviseransonic design methods for airfoils and wings in which the shape and the surrounding body-fitted mesh are both generated analytically, and the control is the mapping function. The method has also been implemented for both transonic potential flows and transonic flows governed by the Euler equations using an alternative formulation which employs numerically generated grids, so that it can treat more general configurations. Here results are presented for three-dimensional design cases subject to supersonic flows governed by the Euler equation.

Reuther, James↗

Loads Induced on a Flat-Plate Wing by an Air Jet Exhausting Perpendicularly through the Wing and Normal to a Free-Stream Flow of Mach Number 2.0

Measurements were made of loads induced on a flat-plate wing by an air jet exhausting perpendicularly through the wing and normal to the free-stream flow.The investigation was conducted at a free-stream Mach number of 2.0 and a Reynolds number per foot of 14.4 x 10(exp 6). An axially symmetric sonic nozzle and two supersonic nozzles were employed for the jets. The supersonic nozzles consisted of an axially symmetric nozzle with exit Mach number of 3.44 and a two-dimensional nozzle with exit Mach number of 1.76. The ratio of nozzle total pressure to free-stream static pressure was varied from 20 to 110. Negative loads were induced on the flat-plate wing by all the jets. As the nozzle pressure ratio was increased the magnitude of interference loads due to jet thrust decreased. The chordwise center-of-pressure location generally moved toward the nozzle center line as the pressure ratio was increased.

Janos, Joseph J.↗

Test Report on Three-and Six-Component Measurements on a Series of Tapered Wings of Small Aspect Ratio (Partial Report: Elliptic Wing)

The report UM No. 1023/1 which presented the results of measurements for a series of trapezoidal wings was the beginning of a series on wings with aspect ratio 1 to 3 and various contours. In report No. 1023/1 the aspect ratio (Lambda = 4/3) remained the same; the tapering was modified. The present report gives the results of the series of elliptic wings. Here the aspect ratio varies from 1 to 2 with the sweepback. The contour is formed by elliptic arcs. The influence of sweepback and contour upon the neutral point is shown.

Lange↗

The Effect of Lateral Inclination of the Thrust Axis and of Sweepback of the Leading Edge of the Wing on Propulsive and Net Efficiencies of a Wing-Nacelle-Propeller Combination

This report describes and gives the results of tests made to determine the effect of lateral inclination of the propeller thrust axis to the direction of flight. A wing-nacelle-propeller combination with the nacelle axis located successively parallel to and at 15 degrees to the perpendicular to the leading edge of a wing was tested with the combination at several angles of yaw. Tests of the wing alone at the same angles of yaw were also made. The data are presented in the usual graphic form. An increase in propulsive efficiency with increase in angle of the thrust axis was found. The change in net efficiency, found by charging the whole nacelle drag to the power unit, was negligible, however, within the range of the tests.

Wood, Donald H.↗