Measurements of two-dimensional derivatives on a wing-aileron-tab system with a 1541 section aerofoil. Part 2 direct tab and cross aileron-tab derivatives

Abstract

Measurements have been made of the direct tab derivatives and cross aileron-tab derivatives for a 1541 section two-dimensional aerofoil (N.P.L. 282) with a 20 per cent aileron and 4 per cent (approx.) tab. In addition some measurements of the direct aileron derivatives have been made for comparison with earlier results together with a number of static derivatives for the wing and controls. The influence is shown of frequency parameter, Reynolds number, position of transition, mean tab angle and sealing of the control hinge gaps. Some tests have been made with the aileron set at minus 8 deg and the tab at plus 12 deg for which condition the hinge moment on the aileron was zero. Reasonable agreement with the values given by the 'equivalent profile' theory is shown for both direct damping derivatives and for the direct tab stiffness derivative. The direct aileron stiffness derivative shows some departure from the theoretical value when ω > 1.