Third Way of Development of Single-Stage-to-Orbit Propulsion

Considering a numberofoptionsfora space-launch vehicle-propulsion system,between advancedrocketmotors and airbreathers,inparticular,thermallyintegrated rocket-basedcombined-cycles,anewcyclethathasbeengiven thenameKLIN (meaning wedgein Russian ), is proposed asthe“ third way.” Itconsists of a combination of a liquid rocket engine and a deep-cooled turbojet (with oxygen addition to atmospheric air ). Currently, the KLIN concept is considered for application with a vertical takeoff horizontal landing vehicle, with the turbojet and the rocket engine optimized individually, with a possibility for incorporating an aerospike-type nozzle. Retaining a rocket trajectoryup toMach 3,theturbojetandrocketengineareassumed tooperatetogetherfromtakeoffwitha gradual reduction in the deep-cooled turbojet output, e nally terminating the turbojet at Mach 6. It can be shown that the KLIN can be manufactured with available or foreseeable technology, and provides a combination of engine weight and specie c impulse that yields twice the payload mass fraction, in addition to other advantages, compared with a rocket-engine-operated vehicle.