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Reduction of wave drag of wing-body combinations at supersonic speeds through body distortions

Description: Report presenting some methods providing sizable reductions in drag for aspect ratios of current interest. The drag savings are maintained over a wide Mach number range, particularly for low-aspect-ratio wings. A significant part of the drag reduction is found to be due to the nonaxisymmetric distortion.
Date: April 13, 1956
Creator: Pitts, William C.
Partner: UNT Libraries Government Documents Department

Determination of Shapes of Boattail Bodies of Revolution for Minimum Wave Drag

Description: By use of an approximate equation for the wave drag of slender bodies of revolution in a supersonic flow field, the optimum shapes of certain boattail bodies are determined for minimum wave drag. The properties of three specific families of bodies are determined, the first family consisting of bodies having a given length and base area and a contour passing through a prescribed point between the nose and base, the second family having fixed length, base area, and maximum area, and the third family having given length, volume, and base area. The method presented is easily generalized to determine minimum-wave-drag profile shapes which have contours that must pass through any prescribed number of points. According to linearized theory, the optimum profiles are found to have infinite slope at the nose but zero radius of curvature so that the bodies appear to have pointed noses, a zero slope at the body base, and no variation of wave drag with Mach number. For those bodies having a specified intermediate.diameter (that is, location and magnitude given), the maximum body diameter is shown to be larger, in general, than the specified diameter. It is also shown that, for bodies having a specified maximum diameter, the location of the maximum diameter is not arbitrary but is determined from the ratio of base diameter to maximum diameter.
Date: August 21, 1951
Creator: Adams, Mac C.
Partner: UNT Libraries Government Documents Department

The use of pure twist for drag reduction on arrow wings with subsonic leading edges

Description: Report presenting linearized-theory calculations of the drag reduction achieved by applying the first three terms of a power series for twist to flat delta wings. For the family of wings investigated, the maximum drag reduction is 2 percent in the medium sweepback range with a steady diminution in both directions. Results for the delta and arrow wings and the optimum settings are provided.
Date: August 1957
Creator: Grant, Frederick C.
Partner: UNT Libraries Government Documents Department

Combustion in the Wake as a Means of Body-Drag Reduction as Determined from Free-Flight Tests of 40-Millimeter Shells

Description: The results of free-flight drag tests of 40-millimeter shells conducted by the National Advisory Committee for Aeronautics for the Ballistic Research Laboratories, Ordnance Department, U. S. Army, are presented. A drag reduction at supersonic speeds of approximately 20 percent of the projectile's drag was obtained by combustion in the wake of the projectile in flight.
Date: 1953
Creator: Welsh, Clement J.
Partner: UNT Libraries Government Documents Department

Preliminary Tests of Blowers of Three Designs Operating in Conjunction with a Wing-Duct Cooling System for Radial Engines, Special Report

Description: This paper is one of several dealing with methods intended to reduce the drag of present-day radial engine installations and improve the cooling at zero and low air speeds, The present paper describes model wind-tunnel tests of blowers of three designs tested in conjunction with a wing-nacelle combination. The principle of operation involved consists of drawing cooling air into ducts located in the wing root at the point of maximum slipstream velocity, passing the air through the engine baffles from rear to front, and exhausting the air through an annular slot located between the propeller and the engine with the aid of a blower mounted on the spinner. The test apparatus consisted essentially of a stub wing having a 5-foot chord and a 15-foot span, an engine nacelle of 20 inches diameter enclosing a 25-horsepower electric motor, and three blowers mounted on propeller spinners. Two of the blowers utilize centrifugal force while the other uses the lift from airfoils to force the air out radially through the exit slot. Maximum efficiencies of over 70 percent were obtained for the system as a whole. Pressures were measured over the entire flight range which were in excess of those necessary to cool present-day engines, The results indicated that blowers mounted on propeller spinners could be built sufficiently powerful and efficient to warrant their use as the only, or chief, means of forcing air through the cooling system, so that cooling would be independent of the speed of the airplane.
Date: June 1939
Creator: Biermann, David & Valentine, E. Floyd
Partner: UNT Libraries Government Documents Department

Comparison of the minimum drag of two versions of a modified delta-wing fighter as obtained from flight tests of rocket-boosted models and equivalent bodies between Mach numbers of 0.80 and 1.64

Description: Report presenting an investigation to determine the reduction in minimum drag that could be obtained at supersonic speeds by redesigning the fuselage and reducing the wing and tail thickness of a modified delta-wing fighter-type airplane. Results regarding the mass-flow ratio, total-pressure recovery, and drag are provided.
Date: September 24, 1956
Creator: Hasting, Earl C., Jr. & Mitcham, Grady L.
Partner: UNT Libraries Government Documents Department

The Reduction in Drag of a Forward-Sloping Windshield

Description: "This paper gives results of a short investigation of the drag of a forward-sloping closed-cabin windshield. The drag of the windshield in both the original and a final modified form was determined from tests in the variable-density wind tunnel. The final form of the windshield was arrived at by modifying the original as the result of flow observations in the N.A.C.A. smoke tunnel. The investigation studied the utility of the N.A.C.A. smoke tunnel as applied to reducing the drag of objects for which the full dynamic scale could not be approached in the smoke tunnel, but designers should find the results of the flow observations and drag measurements of value" (p. 1).
Date: December 1933
Creator: Jacobs, Eastman N.
Partner: UNT Libraries Government Documents Department

Experimental Investigation of a Method of Wave-Drag Reduction for Combinations Employing Quasicylindrical Bodies and Swept Wings at Supersonic Speeds

Description: "Axisymmetric and nonaxisymmetric body distortions designed by the method of NACA TN 3722 were tested to determine the amount of wave-drag reduction obtainable when applied to swept-wing-body combinations over a Mach number range of 1.39 to 1.97. Two wings of aspect ratios 1.33 and 2.67 were tested on different bodies. Both the axisymmetric and nonaxisymmetric distortions produced drag reductions" (p. 1).
Date: February 19, 1957
Creator: Hickey, Daniel P.
Partner: UNT Libraries Government Documents Department

Drag Reduction by Suction of the Boundary Layer Separated Behind Shock Wave Formation at High Mach Numbers

Description: "With an approach of the velocity of flight of a ship to the velocity of sound, there occurs a considerable increase of the drag. The reason for this must be found in the boundary layer separation caused by formation of shock waves. It will be endeavored to reduce the drag increase by suction of the boundary layer. Experimental results showed that drag increase may be considerably reduced by this method" (p. 1).
Date: July 1947
Creator: Regenscheit, B.
Partner: UNT Libraries Government Documents Department

General theory of wave-drag reduction for combinations employing quasi-cylindrical bodies with an application to swept-wing and body combinations

Description: Report presenting an investigation of the wing-body interference of NACA TN 2677 applied to symmetric wings in combination with quasi-cylindrical bodies, which permits the direct calculation of pressure-distribution changes produced by body shape changes. The theory is used to determine the relative magnitude of wave-drag reduction produced by changes in cylinder cross-sectional area and shape.
Date: September 1956
Creator: Nielsen, Jack N. & Pitts, William C.
Partner: UNT Libraries Government Documents Department

Application of wing-body theory to drag reduction at low supersonic speeds

Description: Report presenting a method for extending to higher Mach numbers the region of low drag attainable for wing-body combinations by the use of the transonic area rule. To a good approximation, the drag depends only on the longitudinal distributions of area and moments of area about the vertical plane of symmetry parallel to the free-stream direction. The experimental results confirm the theory in that the zero-lift wave drag of a wing-body configuration over a range of low supersonic Mach numbers.
Date: January 28, 1955
Creator: Baldwin, Barrett S., Jr. & Dickey, Robert R.
Partner: UNT Libraries Government Documents Department

Pressure drag of bodies at Mach numbers up to 2.0

Description: From Memorandum: "The drag of bodies has now assumed greater importance because, as shown in NACA RM L53I15a, 1953 and NACA RM A53H18a, 1953, the transonic drag rise of an airplane can be the same as its equivalent body. Obviously, the airplane designer would like his airplane to have a low-drag equivalent body. This paper shows some of the factors which minimize the drag of bodies at transonic and supersonic speeds and shows some of the penalties caused by deviating from low-drag body shapes. Drag reductions can be obtained in two ways, first, through increasing the body fineness ratio, and second, through better shaping of the body profile at a given fineness ratio. The effects of fineness ratio are discussed first and then, more completely, detail-shape effects."
Date: November 18, 1953
Creator: Nelson, Robert L. & Stoney, William E., Jr.
Partner: UNT Libraries Government Documents Department

Wing-flow study of pressure-drag reduction at transonic speed by projecting a jet of air from the nose of a prolate spheroid of fineness ratio 6

Description: Report presenting a study of the pressure-drag reduction obtained by projecting a high-energy jet of air from the nose of a prolate spheroid at transonic speeds. Results regarding the pressure distribution on the body, pressure drag, shadowgraphs, and some notes regarding the slope of the body and level of shear at the jet exit are provided.
Date: October 26, 1951
Creator: Lopatoff, Mitchell
Partner: UNT Libraries Government Documents Department

Theoretical Investigation of Drag Reduction in Maintaining the Laminar Boundary Layer by Suction

Description: "Maintenance of a laminar boundary layer by suction was suggested recently to decrease the friction drag of an immersed body, in particular an airfoil section. The present treatise makes a theoretical contribution to this question in which, for several cases of suction and blowing, the stability of the laminar velocity profile is investigated. Estimates of the minimum suction quantities for maintaining the laminar boundary layer and estimates of drag reduction are thereby obtained" (p. 1).
Date: June 1947
Creator: Ulrich, A.
Partner: UNT Libraries Government Documents Department