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Preliminary Investigation in the NACA Low-Turbulence Tunnel of Low-Drag Airfoil Sections Suitable for Admitting Air at the Leading Edge

Description: An investigation was carried out in the NACA low-turbulence tunnel to develop low-drag airfoil sections suitable for admitting air at the leading edge. A thickness distribution having the desired type of pressure distribution was found from tests of a flexible model. Other airfoil shapes were derived from this original shape by varying the thickness, the camper, the leading-edge radius, and the size of the leading-edge opening. Data are presented giving the characteristics of the airfoil shapes in the range of lift coefficients for high-speed and cruising flight. Shapes have been developed which show no substantial increases in drag over that of the same position along the chord. Many of these shapes appear to have higher critical compressibility speeds than plain airfoils of the same thickness. Low-drag airfoil sections have been developed with openings in the leading edge as large as 41.5 percent of the maximum thickness. The range of lift coefficients for low drag in several cases is nearly as large as that of the corresponding plain airfoil sections. Preliminary measurements of maximum lift characteristics indicate that nose-opening sections of the type herein considered may not produce any marked effects on the maximum lift coefficient.
Date: July 1, 1942
Creator: von Doenhoff, Albert E. & Horton, Elmer A.
Partner: UNT Libraries Government Documents Department

Effect of Mach and Reynolds numbers on the maximum lift coefficient obtainable in gradual and abrupt stalls of a pursuit airplane equipped with a low-drag wing

Description: Report discussing flight tests on a low-drag wing pursuit airplane to determine the effects of Mach and Reynolds numbers on the maximum lift coefficient obtainable in gradual and abrupt stalls. The obtainable maximum lift coefficient was found to be greatly affected by the Mach and Reynolds numbers in gradual stall. In abrupt stalls, the maximum lift coefficient was affected by the Mach number, but not the Reynolds number.
Date: July 6, 1945
Creator: Spreiter, John R.; Galster, George M. & Blair, William K.
Partner: UNT Libraries Government Documents Department

Lift tests of a 0.1536c thick Douglas airfoil section of NACA 7-series type equipped with a lateral-control device for use with a full-span double-slotted flap on the C-74 airplane

Description: Report discussing lift tests on a two-dimensional airfoil model similar to a Douglas C-74 with a double-slotted flap and lateral-control device. Information about the maximum lift coefficient, aileron and flip effectiveness, and flap stall is provided.
Date: March 1945
Creator: Nuber, Robert J. & Rice, Fred J., Jr.
Partner: UNT Libraries Government Documents Department

Critical Mach Numbers of Thin Airfoil Sections with Plain Flaps

Description: Critical Mach number as function of lift coefficient is determined for certain moderately thick NACA low-drag airfoils. Results, given graphically, included calculations on same airfoil sections with plain flaps for small flap deflections. Curves indicate optimum critical conditions for airfoils with flaps in such form that they can be compared with corresponding results for zero flap deflections. Plain flaps increase life-coefficient range for which critical Mach number is in region of high values characteristic of low-drag airfoils.
Date: April 1, 1946
Creator: Pardee, Otway O'm. & Heaslet, Max A.
Partner: UNT Libraries Government Documents Department

Theoretical investigation of methods for computing drag from wake surveys at high subsonic speeds

Description: Report discusses graphs of constants meant to be used with a knowledge of maximum total head loss, static-pressure decrement, and integral of total-head loss across the wake of an airfoil to determine the section profile-drag coefficient. Computations of free-stream Mach numbers for certain assumed types of total-pressure distribution in the wake are provided to compare theoretical drag coefficients as determined by other equations based on the momentum method. While some disagreements are found, the more rapid technique is usable for wide variations in wake shapes for a Mach number range of 0.5 to 1.0.
Date: June 1945
Creator: Heaslet, Max A.
Partner: UNT Libraries Government Documents Department

Additional design charts relating to the stalling of tapered wings

Description: From Introduction: "The present report, therefore, may be considered a supplement to reference 1. The combined scope of the stall charts of reference 1, designated A, and of the present work, designated B, is summarized in the following table: For the wing with root thickness ratio to 18 was also investigated.
Date: January 1943
Creator: Harmon, Sidney M
Partner: UNT Libraries Government Documents Department