Impact Of Control Provisions On Mission Performance Of Jet VTOL Aircraft Using Reaction Control Systems

Control power composition and usage are characterized. It is demonstrated that handling quality considerations dictate large control power margins over minimum levels for performing maneuvers, but control utilization distributions show that these large control demands are sporadic. A fully variable bleed reaction control system which capitalizes on this characteristic is compared with various constant bleed systems. The thrust losses associated with control provisions with each system are presented for a typical transonic jet VTOL design employing the composite propulsion system concept. The radius penalty associated with the increased lift engine size required to maintain a constant takeoff gross weight is presented for each system and the gross weight increase required to maintain a given close support mission radius is defined. In addition, the radius capability afforded by a given propulsion system size is defined for each system. It is shown that fully variable bleed system with the engine tailored to match control demands has substantial advantages over other systems, particularly as the mission performance requirements are increased.