Adaptive Fuel Control for Helicopter Applications

A United States Army-sponsored computer- aided study of a twin engine helicopter is being conducted to develop new engine control strategies for microprocessor- based fuel control systems. Some of these concepts are classically adaptive in that the control modifies itself on-line to deal with engine deterioration, surge or failure. In addition, the permanent control concepts are inherently adaptive in that helicopter capability is enhanced over a wide range of operating situations. For example, engine power recovery is improved with rotor speed derivative control which allows increased transient load factors and improved handling qualities in maneuvering flight. Fuel consumption is minimized in cruise by seeking out the optimum rotor speed. Rotor drive train torsional damping is increased by utilizing the fast combustive power of the engine to counter output shaft resonances. Studies indicate that very few hardware modifications are required, therefore, a substantial payback may be achieved by implementing these new control features into the software of current generation microprocessor-based fuel control systems.