Comparative Study on Options for High-Speed Intercontinental Passenger Transports: Air-Breathing- vs. Rocket-Propelled
- Paper number
IAC-05-D2.4.09
- Author
Dr. Martin Sippel, Deutsches Zentrum fur Luft und Raumfahrt e.V. (DLR), Germany
- Year
2005
- Abstract
Since the demise of Concorde operation, intercontinental travel is restricted to low-speed, subsonic, multi-hour flight. However, the scientific and political interest in hypersonic passenger airliners is still alive, as has been recently demonstrated by an ongoing European Union (EU) research project. Conventional wisdom assumes to operate these transport craft, depending on the flight Mach-number, by combined air-breathing turbo-jet-RAM-, or SCRAM-engines. Although these propulsion systems seem to be feasible in principle, their utilization is still quite far away in the future due to technical challenges, development-, and operational cost. The technical demonstration of SCRAM has reached the subscale level at best. An interesting alternative in the field of high-speed intercontinental passenger transport vehicles might be a rocket-propelled ballistic, suborbital craft. The functionality of rocket propulsion is a proven technology since decades. Such a rocket engine powered vehicle would rapidly climb out of atmosphere, accelerate to about 7 km/s, and be able to reach its destination 15000 to 18000 km downrange in less than 1 hour. The flight durations are three to four times lower than those of even the most advanced air-breathing systems. On the downside, rocket propulsion is up-to-date inherently less reliable than air-breathing engines and its life time is considerably lower. This paper investigates the technical options for high-speed intercontinental passenger transports on a preliminary basis. Horizontal take-off hypersonic air-breathing airliners are assessed as well as vertical take-off, ballistic rocket powered stages, capable of a safe atmospheric reentry. The study includes a preliminary sizing and performance assessment of all investigated types. The aerodynamic shape of the air-breathing hypersonic airliners is defined to fulfill the L/D and range requirements. The propulsion system including air-intake and nozzle is integrated into the preliminary design. The rockets are based on an advanced but technically conservative approach not relying on any exotic technologies. The two stage, fully reusable vehicle is designed as an “overly reliable” system to overcome the safety deficits of current state-of-the-art launchers. An engine-out capability is integrated for example. The analysis critically assesses the technical options, technology demands, and tries to evaluate the available options on a sound basis. Supported by the results of the technical study, some programmatic issues concerning space flight are finally discussed. Even in the case that only a very small portion of the upper business travel segment could be tapped by a rocket-propelled intercontinental passenger transport, the resulting launch rates per year would be far in excess of any other credible scenario. This form of space tourism, not only attracting the leisure market, would, as a byproduct, enable to considerably reduce the cost of space transportation to orbit.
- Abstract document
- Manuscript document
IAC-05-D2.4.09.pdf (🔒 authorized access only).
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