Optimal Location and Size of Canards for Aeroelastic Actuation in Aerospace Vehicles

Abstract

The present study investigates the problem of locating and resizing canard control surfaces in order to achieve a desired trim flight control force. The problem of a generic flexible aerospace vehicle having canard as the main flight control surface is formulated and a simplified analytical model is developed which demonstrates the feasibility of determining the geometric configuration and location of the canard that recovers the desired control force by relocating and resizing the existing canard. Next, the above concept is extended to a practical aerospace vehicle configuration using an in-house software tool for performing the static aeroelastic load analysis and these results are obtained for the supersonic flight regime, by also considering variation in the structural stiffness of the body of the aerospace vehicle. The results are obtained for a trim analysis, with inertia force corrections taken into account, and plots are generated for the required canard location as a function of the vehicle body stiffness factor, for two different values of the canard size and for a typical supersonic Mach number. Lastly, the effect of canard structural flexibility on the overall control derivative is investigated, through an equivalent lumped torsional stiffness approach. These results clearly show that it is possible to locate and resize the canard such that the desired control force is recovered, using the favourable aeroelastic effects of the body of the aerospace vehicle. These results are considered to be applicable both for the multidisciplinary design of aerospace vehicle as well as for on-board implementation as a part of the flight control algorithm.