Researchers seek new studies on Mach 5-plus air-breathing propulsion concept as X-43A testing reaches climax

NASA hypersonic researchers are proposing a new initiative to take forward studies of the Mach 5-plus air-breathing propulsion concept as part of the agency's wider space exploration mandate.

The effort is also aimed at building on the knowledge gained with the Hyper-X programme that is due effectively to finish with the third and final flight of the X-43A vehicle, planned on or around 15 November. NASA hopes the last flight will demonstrate sustained supersonic-combustion ramjet (scramjet) operations at M10, having reached M6.83 on the second X-43A flight on 27 March.

NASA admits, however, the test is a risk, but says that a second successful flight will aid chances of funding for its new plan, which is now 95% complete, says Hyper-X programme manager Vincent Rausch. "We're trying to flesh it out, and get some analysis behind the process," he adds, saying data from the last two X-43A tests will form an important platform on which to build the new programme.

The plan, proposed to NASA's Aeronautics Mission Research Directorate by an inter-centre NASA team from Ames, Dryden, Glenn and Langley, is broadly aimed at research to support air-breathing hypersonic concepts for service entry over the next 20-25 years. The proposal also includes work on concepts that could form the subject of mid-term "'spiral" developments, such as an M7 air-breathing hypersonic first-stage space launch vehicle incorporating a turbine-based combined cycle (TBCC) engine.

"With such a vehicle we could move right into development, although there are still big issues, such as the integration of the TBCC and the development of reusable cryogenic tanks," says Rausch. The study TBCC configuration will be a turbojet based on a current military turbofan, such as the Pratt & Whitney F135, burning hydrocarbon for the jet phase and liquid hydrogen for the ramjet/scramjet phase of the flight. Such a vehicle could therefore be feasible for near term use around 2015, he adds.

Although NASA's plan includes work with the US Department of Defense, industry and academia, Rausch says it does not affect on-going hypersonic work the agency is conducting with the US Air Force, Navy and Defense Advanced Research Projects Agency on efforts such as Falcon, Single Engine Scramjet Demonstrator and HiFly.



Source: Flight International