Enhancement of endurance performance by periodic optimal camber control

A new method for endurance maximization is proposed. This method consists of the periodic optimal control of variable camber in a coordinated process with a corresponding control of throttle and elevator. It is shown that the proposed method can significantly increase the endurance when compared with the best steady-state flight. Using camber as a control provides an efficient means for improving the lift/drag ratio at each flight condition during the unsteady phases of periodic optimal endurance cruise. Engine considerations include fuel consumption during idling phases. They also address a reduction of the number of engine cycles in regard to alternate operating at a high and low thrust setting. The optimal control technique used is based on the minimum principle and the method of multiple shooting. Necessary conditions for optimality, including optimal control of variable camber setting, are analyzed.