Augmented Vectored Thrust Engines and the Problem of Avoiding Hot Gas Recirculation

It can be argued that the vectored thrust engine is one of the best propulsion systems for V/STOL combat aircraft. The next step is to consider the problems to be overcome in integrating such a powerplant into the airframe. A critical installation issue, and one which is not unique to vectored thrust systems, is that of hot exhaust gas recirculation. In this paper some of Rolls-Royce’s hot gas recirculation experience is described, covering, in particular, the creation of a specialized recirculation test facility and some sample test results. The application of the results to a vectored thrust installation is discussed, together with some of the implications for the aircraft designer. Finally, some comments are made regarding the requirements of other V/STOL propulsion systems to avoid excessive hot gas recirculation.