It is often desirable, in the design of aerodynamic control surfaces, to predict the center of pressure, and hence the hinge moment, in order to optimize the actuator requirement. If the center of pressure can then be controlled, coupled with an innovative structural concept for the design of supersonic missile control fins subject to specified design objectives and constraints. The structural concept involves use of directional material properties to control the axial location of the center of pressure by taking advantage of aeroelastic fin deformation. The present technology is applicable to the design of control surfaces which generate a desired normal force with minimum hinge moment resulting in reduced actuator requirements.

An enhanced panel method-based aerodynamic code, a structural finite element code, and an optimization code were combined into an aeroelastic design procedure designated TAILOR. The design procedure was successfully applied to an aluminum lifting surface with spanwise grooves. NEAR is interested in extending the technology to subsonic speeds, other design objectives, and the analyses and design of flexible, active control fin surfaces with embedded actuators which change the camber shape.

An example involving a grooved aluminum trapezoidal fin is shown in the sketches. The axial center of pressure location of the flexible fin is shown relative to that of the steel rigid fin as a function of angle of attack for three supersonic Mach numbers. The design objective was to shift the center of pressure location forward to the maximum possible extent by varying the direction of the grooves of the flexible fin. The design calculations indicated that the center of pressure could be shifted forward, without appreciable change in fin normal force, with the grooves in a near spanwise direction. The experimental data confirm this result. Calculations also show that increasing the dynamic pressure at constant Mach number causes a forward shift in center of pressure. Therefore, it appears possible to maintain the axial location of center of pressure at its low dynamic pressure value by employing a chordwise flexible fin concept thereby minimizing variations in hinge moment.

Commercial Applications: Rapid analysis and design of advanced, aeroelastic wind tunnel model components, lifting surfaces of high performance aircraft, and body and fins of advanced missile concepts including active fin structure control.

Dillenius, M. F. E. et al, "Aeroelastic Tailoring Procedure to Optimize Missile Fin Center of Pressure Location." AIAA Paper 92-0080.