Details have emerged of the US Defense Advanced Research Projects Agency's (DARPA) plans to test fly its two expendable dart-shaped Hypersonic Technology Vehicle (HTV)-2 demonstrators.
To be launched by Orbital Sciences Minotaur solid-fuel rockets from Vandenberg Air Force Base, HTV-2a will fly in May 2009 and HTV-2b will follow in the October of that year.
While the two flights have separate trajectories they will both impact near the Kwajalein Atoll test site in the Pacific Ocean. HTV-1 was a ground test demonstrator.
The first flight will demonstrate performance characteristics, and the second cross-range manoeuvring as well as thermal protection system performance.
The two HTVs will use inertial navigational measurement units and global positioning system (GPS) for guidance, while testing satellite communications and GPS reception through the plasma that will surround the vehicles during their flight.
"The HTV-2 will have a plasma probe onboard [to examine the hot gases] and we are expecting it to have good lift-over-drag performance," said DARPA's tactical technology office deputy director Steve Walker, speaking at the 15th AIAA International space planes, hypersonic systems and technologies conference in Dayton, Ohio on 28 April.
The next flight demonstrator after HTV-2 will be Blackswift. Lockheed Martin and Pratt & Whitney Rocketdyne were working on a waverider type vehicle called the HTV-3 but there are no plans to build this and the concept has been designated HTV-3X.
Blackswift is a reusable hypersonic demonstrator and the prime contractor for its construction and flight test is yet to be selected. The closing date for tenders will be mid-May.
Walker adds that Blackswift will not have a waverider shape, citing the need for a slimmer configuration to improve performance in transonic flight.