Integrated Propulsion System Requirements for Control of STOVL Aircraft

This paper describes an evaluation of propulsion system requirements and capability for a Short Take Off / Vertical Landing (STOVL) aircraft employing modulation of the propulsive lift distribution for pitch and roll control in hover. The effects of propulsive lift nozzle configuration and propulsion system dynamic response were evaluated using a combined system simulation consisting of a six degree of freedom aircraft model, engine model and integrated flight/propulsion control. The response and stability of propulsive lift control is compared with control by reaction jets supplied by engine bleed. Aircraft performance is demonstrated in simulated STOVL maneuvers using a dynamic pilot model. The conclusion of this study is that propulsive lift control of aircraft pitch and roll is feasible and can provide as much as a 10 percent increase in engine lift rating over systems which employ reaction control alone. The dynamic response of practical propulsive lift configurations, however, is less than that of reaction control configurations which must be offset through integration of the propulsion system and its control.