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Directing the exhaust of a turbojet engine through an ejector pump can significantly increase the jet thrust. This paper is a review of recent advances in the development of thrust augmenting ejectors for VSTOL aircraft. Progress in developing a theory of ejector operation, and related efforts in analysis and prediction will be summarized. Studies of turbulent mixing and duct design which have led to improvements in ejector performance will also be described. Finally, research problems of current interest and the likely direction of future airplane programs will be discussed.

Analysis and testing are used to show the feasibility of an innovative shaft driven lift fan propulsion system for supersonic STOVL aircraft. Dual cycle operation of the cruise engine makes it possible to convert some of the jet thrust to shaft horsepower for driving the lift fan. Operation of the propulsion system is described and it is analytically shown that the designs of the engine, drive shaft, and clutch are within the state of the art. A demonstrator engine and lift fan were assembled from available components and operated for almost 200 hours in a full size airframe model. Testing proved the feasibility of changing the engine cycle to drive the lift fan, and of rapidly transferring thrust back and forth between the engine and lift fan to provide pitch control. The durability of the mechanical drive system and flight weight gearbox were also demonstrated.