Book Description

A boundary-layer-transition and profile-drag investigation was conducted in flight by the National Advisory Committee for Aeronautics on an experimental low-drag wing installed on a P-47 airplane designated the XP-47F and supplied by the Army Air Forces. The wing incorporates airfoil section that vary from an NACA 66(215)-1(16.5), a = 1.0 at the plane of symmetry to an NACA 67(115)-213, a = 0.7 at the tip. The surface of the wing as constructed was found to have such a degree of waviness that it had to be refinished in order to obtain the performance generally expected of low-drag airfoils. Measurements were made at a section outside the propeller slipstream with smooth and with standard camouflage surfaces and on the upper surface of a section in the propeller slipstream with the surface smoothed. Tests were made in normal flight - that is, in level flight and in shallow dives - at indicated airspeeds ranging from about 150 to 300 miles per hour and in steady turns at 300 miles per hour with normal acceleration from 2g to 4g. These speed and acceleration limits were imposed by structural considerations. The tests in normal flight covered a range of section lift coefficient from about 0.58 to 0.15, of Reynolds number from about 9 x 106 to 18 x 106, and of Mach number from about 0.27 to 0.53. In the tests in turns at 300 miles per hour, the range of section lift coefficient was extended to 0.63.