Measurement of Direct Moment Derivatives in the Presence of Sting Plunging (Determination Experimentale des Derivees de Moments Aerodynamiques en Presence du Mouvement de Pillonnement du Dard Support)

摘要

This paper presents a review and extension of methods for determining the effects of sting oscillations on the measurement of dynamic moment derivatives, based on linear as well as nonlinear models. It is shown that two of the linearized methods will reduce to the same result, applicable to low-lift configurations and suitable for on-line data reduction. The location of the effective axis of rotation is determined for a model executing planar oscillations in two degrees of freedom. The equations for the effect of plunging on the derivatives due to angular oscillation can be simplified by relating the sting deflection parameters to the co-ordinate of this axis. Therefore, both the correction of the measured derivatives and their transformation to the reference centre can be accomplished after a single measurement is made, namely the location of the effective axis. The requirements for performing sting plunging corrections for aircraft configurations at high angles of attack are discussed. (Author)