Abstract:

Considerations in Designing the Air-Breathing Engines for a Spaceplane Acceleration Mission

Performance requirements of turbo-jets for combined air-breathing-rocket spaceplanes are different from those for most supersonic fighter engines. These requirements will be parametrically investigated in this paper, based on the booster stage of the DSL TSTO-concept, and the preliminary design of a high performance turbofan will be described. Although the analysis is calculated for the DSL supersonic carrier aircraft (Mach-number range 2.7 to 3.5), the presented trend is transferable to systems with similar propulsion.

To select the characteristic engine parameters, such as the compression ratio (OPR), bypass-ratio, and turbine entry temperature (TET), a multi-dimensional trend-analysis will be performed. For this purpose, a combined numerical engine performance calculation and a simulation of the DSL-trajectory will deliver the propellant mass ratio for each combination of engine parameters. Using these results, the engine type and target data will be chosen.

The preliminary design of the complete air-breathing engine, including the air-intake and the nozzle, is executed in a next step. Using a newly developed fast analytical design-tool, and also finite-element calculations, a low bypass, moderate OPR turbofan engine will be designed. This includes a mass breakdown of the main engine parts and an engine weight estimation. In conclusion the complete propulsion system thrust to weight ratios are given for different potential configurations.