The aim of the work outlined in this paper is to compare three different variable cycle jet engine concepts for future SSTs. These engines are: the Turbofan-Turbojet, the Mid-Tandem Fan engine and the Double Bypass Engine. The comparison is carried out on a basis of performance, handling and sizing issues.
This preliminary analysis compares S.F.C., size, variable geometry and cycle changes, and the effect of variable stator on the running lines of each compressor for each engine. The fuel bill, for two standard missions, is estimated as well.
These preliminary results indicate that the three engines are quite similar in terms of general suitability. The Mid Tandem Fan appears to be an attractive proposition from the point of view of sizing, however this comes with a small penalty in fuel consumption.