National Advisory Committee for Aeronautics (NACA) - 735 Matching Results

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Wind-Tunnel Tests of the 1/25-Scale Powered Model of the Martin JRM-1 Airplane. IV - Tests with Ground Board and with Modified Wing and Hull - TED No. NACA 232, Part 4, Tests with Ground Board and with Modified Wing and Hull, TED No. NACA 232

Description: Wind-tunnel tests were made of a 1/25 scale model of the Martin JRM-1 airplane to determine: (1) The longitudinal stability and control characteristics of the JRM-1 model near the water and lateral and directional stability characteristics with power while moving on the surface of the water, the latter being useful for the design of tip floats; (2) The stability and stalling characteristics of the wing with a modified airfoil contour; (3) Stability characteristics of a hull of larger design gross weight; The test results indicated that the elevator was powerful enough to trim the original model in a landing configuration at any lift coefficient within the specified range of centers of gravity. The ground-board tests for evaluating the aerodynamic forces and moments on an airplane in a simulated cross wind indicate a high dihedral effect in the presence of the ground board and, consequently, during low-speed taxying and take-off, large overturning moments would result which would have to be overcome by the tip floats.
Date: September 4, 1947
Creator: Lockwood, Vernard E. & Smith, Bernard J.
Partner: UNT Libraries Government Documents Department

Wing plan forms for high-speed flight

Description: It is pointed out that, in the case of an airfoil of infinite aspect ratio moving at an angle of sideslip, the pressure distribution is determined solely by that component of the motion in a direction normal to the leading edge. It follows that the attachment of plane waves to the airfoil at near-sonic or supersonic speeds (Ackeret theory) may be avoided and the pressure drag may be reduced by the use of plan forms in which the angle of sweepback is greater than the Mach angle. The analysis indicates that for aerodynamic efficiency, wings designed for flight at supersonic speeds should be swept back at an angle greater than the Mach angle, and the angle of sweepback should be such that the component of velocity normal to the leading edge is less than the critical speed of the airfoil sections. This principle may also be applied to wings designed for subsonic speeds near the speed of sound, for which the induced velocities resulting from the thickness might otherwise be sufficiently great to cause shock waves.
Date: January 1, 1947
Creator: Jones, Robert J
Partner: UNT Libraries Government Documents Department