Finally a roadmap towards an operational hypersonic missile development program may be emerging in the form of a new U.S. Air Force project dubbed Riptide. The road starts with hypersonic propulsion technology about to be tested in the X-51A WaveRider program at Edwards AFB, California in a matter of weeks from now.
Led by the Air Force Research Laboratory, the rapid identification and prosecution of targets in denied environments (Riptide) project, would build on the X-51A which is set to demonstrate endothermic hydrocarbon-fueled scramjet engine technology. Unlike X-51A, which is aimed at a 300 sec flight at Mach 6 covering several hundred miles, the Riptide project is expected to call for longer range requirements. Steve Johnston, director of Boeing Advanced Space Exploration estimates it could be "over 1,000" miles, but adds that "at this point the requirements are not really firm." The entire Riptide concept is described as being in the "very early stages as a potential follow-on" he says.
Riptide would consist of “more of an operational representative configuration, and would be more of a systems-level test,” says Johnston who adds that payloads could also be incorporated. The eventual aim would be to flight test a number of vehicles to demonstrate long range strike, quick response capabilities.
Funding for both the longer-term Riptide and a proposed medium-term follow-on effort called X-51A Plus, could depend on the success or failure of the initial WaveRider tests – the first flight of which has been delayed since late last year by test range and supply chain issues, as well as availability of the Air Force B-52 ‘mothership.’ This aircraft will be used to carry the vehicle to launch altitude. Boeing says the first X-51A test may now take place in May, having twice seen scheduled attempts in March and April scrubbed because of re-prioritization of the B-52 to other tests.
Follow-on X-51A 'Plus' versions could follow X-51A and precede Riptide (Guy Norris)
Boeing hopes to pick up funding in Fiscal Year 2011 for a follow-on series of X-51A Plus test vehicles which will provide a stepping stone towards the Riptide configuration by incorporating minor modifications and an expanded performance envelope. Although the 'A Plus' is not yet a program of record, between two and six ‘Plus” vehicles could be covered under the project if it becomes a reality. Johnston confirms that the "A Plus" variants would not be recoverable even though Boeing has studied recoverable concepts, including retractable wings and landing gear.
xact timing for Riptide is not yet determined but is likely to be “a couple of years” after X-51A Plus, says Boeing.