A preliminary comparison of the installed performance of three variable cycle jet engine concepts for future Supersonic Transports is outlined in this paper. These engines, are: the Turbofan-Turbojet, the Mid-Tandem Fan engine and the Double Bypass Engine.The comparison of the uninstalled performance, variable geometry, cycle changes, the effect of variable compressor stators on the running lines of the compressors and sizing assessments for each engine were carried out in Reference 4.An estimate is now made of the installed performance by calculating the air friction, the pre-entry and the afterbody drags, plus the wave drag. A sizing calculation was carried out for the nacelles of all the engines. The uninstalled and installed fuel bills, for two standard missions, are also estimated.These preliminary results indicate that the Turbofan-Turbojet and the Mid Tandem Fan 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. The Double Bypass engine was found to be the least attractive of the powerplants investigated. The differences, however appear to be small.Copyright © 1998 by ASME