Boeing North American has completed initial wind-tunnel work on a scramjet (supersonic combustion ramjet)- powered waverider lifting body.

Now the company is pressing the US Defense Advanced Research Projects Agency (DARPA) to support the effort as part of the development of future hypersonic weapons.

The call comes as work begins on the initial stages of NASA's Hyper-X (Hypersonic Experimental Research Vehicle) programme, which will demonstrate the first use of a non-rocket powered atmospheric vehicle at speeds above Mach 5.

The Hyper-X, like the proposed family of hypersonic weapons, will use air-breathing scramjet technology. It is being developed by a team including Boeing North American.

Thad Sandford, Boeing North American advanced programmes manager, says: "It is important to build hypersonic vehicles because they can go after time-critical targets. He adds: "We have done experiments on a waverider lifting body in the windtunnels here [California] and at NASA Langley."

The research is aimed at developing airframe and propulsion technology for "fast-reaction stand-off weapons", says Sandford. "We have completed initial work and are hoping that the US Navy and DARPA will support it."

Boeing believes interest will be high for several reasons. Air-breathing hypersonic missiles will not require on-board oxygen for fuel, so can be much smaller as a result, trading range for payload.

The use of structural carbon composites and low-density polymer ablatives for thermal protection is also being investigated. this could increase the propellant fraction without affecting range/payload. "It will also hit hardened targets much better," says Sandford, who adds that such high-speed missiles would provide ideal defence-suppression weapons in advance of air strikes by conventional aircraft.

Many of the planned technologies will be tested on the Hyper-X programme, which will undergo flight-testing with the first of four research vehicles around November 1998. Each will be around 3.5m long with a wingspan of 1.6m. The vehicles will be boosted by a modified Orbital Sciences rocket dropped from NASA Dryden's B-52 test aircraft.The first Hyper-X will fly to Mach 7, while the second will fly at speeds up to Mach 5.

The third and fourth vehicles will attempt to reach Mach 10 in late 2000 and 2001, respectively.

Source: Flight International