Abstract:
Summary.--The lift, pitching moment and hinge moment are derived for a delta wing with a trailing-edge flap of constant chord when tile wing is at zero incidence in a supersonic air stream and tile flap oscillates harmonically with small amplitude and low frequency. It is assumed that the wing is sufficiently thin and the amplitude of oscillation sufficiently small to permit the use of linearised theory. Expressions for the various control derivative coefficients are obtained for a particular delta wing of aspect ratio 1.8 and taper ratio 1/7. The investigation covers partial-span flaps; in each case there is a lower limit to the Mach numbers for which the theory applies, though from practical considerations this restriction is not serious. The derivatives are evaluated and tabulated for Mach numbers 1.1, 1.2, 1.4, 1-6, 2.0. The theory is shown to apply without appreciable error, provided that the frequency parameter based on mean chord does not exceed 0.4. The calculated values of hinge-moment damping are compared with preliminary experimental values obtained at the National Physical Laboratory.
