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Two categories of ejector design have been investigated at de Havilland Aircraft of Canada: (1) Trailing edge ejector flap for augmentation of wing lift by supercirculation: primarily for STOL transport type aircraft of high aspect ratio. (2) Chordwise rectangular ejector located adjacent to the fuselage sides for vertical lift: primarily for STOVL combat type aircraft of low aspect ratio. The paper reviews the underlying physical principles of the ejector type of thrust augmentor and suggests a logical procedure for development and optimization by experimental means. Methods of data analysis are shown which provide the foundation for empirical design and some examples of performance are given for each of the two ejector categories defined above. In addition, a new form of primary nozzle is described which serves to distribute the jet and promote fast mixing in the ejector throat.

Some of the fundamentals of powered lift for STOL and STOVL are considered and factors are listed which add substantially to the difficulty of the design task vis-á-vis CTOL. It is shown that the design of a powered lift aircraft represents a complex synthesis and some broad reasons are suggested for limited progress in the field since the Second World War. This introduction serves as a context in which to consider the synthesis of Ejector Lift/Vectored Thrust (EL/VT) as it relates to a multi-role supersonic fighter aircraft. The foundations of the chordwise ejector concept are traced from early tests and reasons given for specific choices. Evolution of the EL/VT hybrid is described and synthesis of the concept is considered element by element with particular reference to factors discussed in the opening section of the paper.