FUNDAMENTAL-CONCEPTS OF VECTORED PROPULSION

Future fighter aircraft may maneuver, especially in the post-stall (PS) domain, by simultaneously directing their jets in the yaw, pitch, and roll coordinates. Consequently, thrust vectoring (TV) may gradually become a key element in helping fighters to survive and win in the close-combat arena. It also provides fighter aircraft with short-takeoff-and-landing (STOL) capabilities. This paper first defines the fundamental concepts associated with pure, or with partial TV powerplants. It then demonstrates that propulsion engineering should be expanded to include such unorthodox engine-design criteria as those of TV maneuverability and controllability. Second, the fundamental concepts of pure vectored propulsion are employed to design, construct, and laboratory test a new type of simultaneous roll-yaw-pitch TV system. Vectored remotely piloted vehicles (RPVs) were then constructed "around" these new propulsion systems. Flight tests of these RPVs since May 1987 have verified the STOL capability and enhanced maneuverability and controllability designable into vectored propulsion systems. They also became the first flight tests of pure vectored propulsion systems. The integrated methodology of laboratory/vectored-RPV-flight tests, as developed for this investigation, has been verified as cost effective and timesaving. Using this methodology a follow-up program was recently launched to help upgrade existing fighter aircraft, such as the F-15, F-16, and F-18, to become partially vectored PS aircraft. Finally, the basic conceptual changes associated with the very introduction of TV engines are summed up in terms of greater emphasis on highly integrated engine/flight-control testing methodologies and on reassessment of conventional concepts.