Drag Minimization Through the use of Mission Adaptive Trailing Edge Flaps and Fuel State Control

Abstract

The paper presents a methodology for minimizing total drag of a high-altitude, long endurance reconnaisance vehicle across its mission by optimal scheduling of flaps and fuel pumping. The methodology accounts for profile and induced drag and includes the effects to drag of trimming the vehicle. The use of conventional, rigidarticulating flaps are considered, in addition to conformal flaps which provide a smooth, continuous camber change and allow for flap twisting. Numerical results are demonstrated on a Lockheed Martin SensorCraft concept that is characterized by a 30 degree wing sweep, a fuel fraction of nearly 60 %, and a constant altitude cruise in which CL varies roughly from 0.5 to 1.2. The results have shown that significant reductions in drag can be achieved with optimal scheduling of flaps and fuel pumping. Drag predictions have been translated to mission range through integration of the Breguet range equation. Results show that between a 5 and 15 % increase in range can be achieved.