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Cooling tests of a single-row radial engine with several NACA cowlings

Description: The cooling of a single-row radial air-cooled engine using several cowling arrangements has been studied in the NACA 20-foot wind tunnel. The results show the effect of the propeller and several cowling arrangements on cooling for various values of the indicated horsepower in the climb condition. A table giving comparative performance of the various cowling arrangements is presented. The dependence of temperature on indicated horsepower and pressure drop across the baffles is shown by charts. Other charts show the limiting indicated horsepower against the pressure drop across the engine and the heat dissipated at various values of the indicated horsepower.
Date: August 20, 1936
Creator: Brevoort, M. J.; Stickle, George W. & Ellerbrock, Herman H., Jr.

Wind-tunnel investigation of effect of interference on lateral-stability characteristics of four NACA 23012 wings, an elliptical and a circular fuselage and vertical fins

Description: Report presents the results of a wind-tunnel investigation of the effect of wing-fuselage interference on lateral-stability characteristics made in the NACA 7 by 10-foot wind tunnel on four fuselages and two fins, representing high-wing, low-wing, and midwing monoplanes. The fuselages are of circular and elliptical cross section. The wings have rounded tips and, in plan form, one is rectangular and the three are tapered 3:1 with various amounts of sweep. The rate of change in the coefficients of rolling moment, yawing moment, and lateral force with angle of yaw is given in a form to show the increment caused by wing-fuselage interference for the model with no fin and the effect of wing-fuselage interference on fin effectiveness. Results for the fuselage-fin combination and the wing tested alone are also given.
Date: August 8, 1940
Creator: House, Rufus O. & Wallace, Arthur R.

An apparatus for varying effective dihedral in flight with application to a study of tolerable dihedral on a conventional fighter airplane

Description: From Summary: "An apparatus for varying effective dihedral in flight by means of servo actuation of the ailerons in response to sideslip angle is described. The results of brief flight tests of the apparatus on a conventional fighter airplane are presented and discussed. The results of an investigation employing the apparatus to determine the tolerable (safe for normal fighter operation) range of effective dihedral on the test airplane are presented."
Date: August 24, 1949
Creator: Kauffman, William M.; Liddell, Charles J., Jr.; Smith, Allan & Van Dyke, Rudolph D., Jr.

Comparison of wind-tunnel and flight measurements of stability and control characteristics of a Douglas A-26 airplane

Description: Stability and control characteristics determined from tests in the Langley 19-foot pressure tunnel of a 0.2375-scale model of the Douglas XA-26 airplane are compared with those measured in flight tests of a Douglas A-26 airplane. Agreement regarding static longitudinal stability as indicated by the elevator-fixed neutral points and by the variation of elevator deflection in both straight and turning flight was found to be good except at speeds approaching the stall. At these low speeds the airplane possessed noticeably improved stability, which was attributed to pronounced stalling at the root of the production wing. The pronounced root stalling did not occur on the smooth, well-faired model wing. Elevator tab effectiveness determined from model tests agreed well with flight-test tab effectiveness, but control-force variations with speed and acceleration were not in good agreement. The use of model hinge-moment data obtained at zero sideslip appeared to be satisfactory for the determination of aileron forces in sideslip. Fairly good correlation in aileron effectiveness and control forces was obtained; fabric distortion may have been responsible to some extent for higher flight values of aileron force at high speeds. Estimation of sideslip developed in an abrupt aileron roll was fair, but determination of the rudder deflection required to maintain zero sideslip in a rapid aileron roll was not entirely satisfactory.
Date: August 11, 1945
Creator: Kayten, Gerald G & Koven, William

Comparative drag measurements at transonic speeds of rectangular sweptback NACA 65-009 airfoils mounted on a freely falling body

Description: From Summary: "Directly comparable drag measurements have been made of an airfoil with a conventional rectangular plan form and an airfoil with a sweptback plan form mounted on freely falling bodies. Both airfoils had NACA 65-009 sections and were identical in span, frontal area, and chord perpendicular to the leading edge. The sweptback plan form incorporated a sweepback angle of 45 degrees. The data obtained have been used to establish the relation between the airfoil drag coefficients and the free-stream Mach number over a range of Mach numbers from 0.90 to 1.27. The results of the measurements indicate that the drag of the sweptback plan form is less than 0.3 that of the rectangular plan form at a Mach number of 1.00 and is less than 0.4 that at a Mach number of 1.20."
Date: August 9, 1945
Creator: Mathews, Charles W. & Thompson, Jim Rogers

Analysis and modification of theory for impact of seaplanes on water

Description: From Summary: "An analysis of available theory on seaplane impact and a proposed modification thereto are presented. In previous methods the overall momentum of the float and virtual mass has been assumed to remain constant during the impact but the present analysis shows that this assumption is rigorously correct only when the resultant velocity of the float is normal to the keel."
Date: August 20, 1945
Creator: Mayo, Wilbur L.

Air flow in the boundary layer of an elliptic cylinder

Description: From Introduction: "The present investigation was carried out for the purpose of supplementing the earlier work with information on the boundary layer under such conditions of air speed and turbulence that transition occurs and the layer is partly laminar and partly turbulent. In the work reported in reference 1, the air speed was about 12 feet per second, and it was assumed that the boundary layer remained in the laminar condition until after separation because the separation point remained fixed and the pressure distribution about the cylinder was unaffected until an air speed of 15 feet per second was reached."
Date: August 6, 1938
Creator: Schubauer, G B

A low-speed experimental investigation of the effect of a sandpaper type of roughness on boundary-layer transition

Description: From Summary: "An investigation was made in the Langley low-turbulence pressure tunnel to determine the effect of size and location of a sandpaper type of roughness on the Reynolds number for transition. Transition was observed by means of a hot-wire anemometer located at various chordwise stations for each position of the roughness. These observations indicated that when the roughness is sufficiently submerged in the boundary layer to provide a substantially linear variation of boundary-layer velocity with distance from the surface up to the top of the roughness, turbulent "spots" begin to appear immediately behind the roughness when the Reynolds number based on the velocity at the top of the roughness height exceeds a value of approximately 600. At Reynolds numbers even slightly below the critical value (value for transition), the sandpaper type of roughness introduced no measurable disturbances into the laminar layer downstream of the roughness. The extent of the roughness area does not appear to have an important effect on the critical value of the roughness Reynolds number."
Date: August 15, 1956
Creator: von Doenhoff, Albert E. & Horton, Elmer A.