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

Abstract

Considering a number of options for a space-launch vehicle-propulsion system, between advanced rocket motors and airbreathers, in particular, thermally integrated rocket-based combined-cycles, a new cycle that has been given the name KLIN (meaning wedge in Russian), is proposed as the "third way." It consists 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 trajectory up to Mach 3, the turbojet and rocket engine are assumed to operate together from takeoff with a gradual reduction in the deep-cooled turbojet output, 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 speci c impulse that yields twice the payload mass fraction, in addition to other advantages, compared with a rocket-engine-operated vehicle. NomenclatureC O = concentration of onboard oxygen, 100% by assumption C A O = concentration of oxygen in normal air, 23.15% C R O = concentration of oxygen in air/oxygen mixture, C A O (1 ¡ } ) + } C O F = local speci c thrust I = local speci c impulsē I A B E = average speci c impulse in the airbreathing phasē I L R E = average speci c impulse of the liquid rocket engine K A= air-to-hydrogen ratio or cooling ratio K 0 = oxygen-hydrogen stoichiometric ratio, 7.937 R T W = vehicle thrust-to-mass ratio R 0 = initial thrust-to-mass ratio of vehicle r = initial thrust-to-mass ratio of propulsion system V f = ight speed W g = exhaust gas velocity D V L R E = speed increment in rocket phase of ight d AF = airframe fraction in gross takeoff weight d EN = engine fraction in gross takeoff weight d V A B E = drag and gravity losses in airbreathing phase d V L R E = drag and gravity losses in liquid rocket phase e = equivalence ratio of combined propulsion } = mass fraction of onboard oxygen in the mixed oxidizer

Effects of Uncertainty in Gas-Surface Interaction on DSMC Simulations of Hypersonic Flows

“…Weaver et al [5] showed that a third-order gPC can accurately reproduce the first two moments of the stagnation point heat transfer for high Mach flows. Moving to a fourth-order gPC changed the mean heat flux by less than 0.1%.…”

“…The analysis by Weaver et al [5] shows that 3 rd order gPC can accurately reproduce (within 0.1%) the first two moments, i.e. the mean and the standard deviation, of the surface heating and stresses for typical hypersonic flows of nonreacting gas.…”