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Because of rising demands to improve aerodynamic performance owing to its impact on vehicle dynamics, efforts were previously made to reduce aerodynamic lift and yawing moment based on steady-state measurements of aerodynamic forces. In recent years, increased research on dynamic aerodynamics has partially explained the impact of aerodynamic forces on vehicle dynamics. However, it is difficult to measure aerodynamic forces while a vehicle is in motion, and also analyzing the effect on vehicle dynamics requires measurement of vehicle behavior, amount of steering and other quantities noiselessly, as well as an explanation of the mutual influence with aerodynamic forces. Consequently, the related phenomena occurring in the real world are still not fully understood.

This paper describes a new passive thermal control device-a Reversible Thermal Panel (RTP)-which changes its function reversibly from a radiator to a solar absorber by deploying/stowing the radiator/absorber reversible fin. The RTP consists of Highly Oriented Graphite Sheets (HOGSs), which have characteristics of high thermal conductivity, flexibility and light weight, as thermal transport units, which can transport the heat from equipment to reversible fin, and of a Shape - Memory Alloy (SMA) as a passively rotary actuator to deploy/stow the reversible fin. The RTP prototype model was designed and fabricated using HOGSs, a honeycomb base palate, and a prototype reversible rotary actuator. The heat rejection performance of the RTP as a radiator and the heat absorption performance as an absorber were evaluated by thermal vacuum tests and thermal analyses. The autonomous thermal controllability achieved using the prototype rotary actuator was also evaluated.