The US Air Force (USAF) plans to fly the Boeing Phantom Works X-51A Waverider hypersonic engine research vehicle at up to Mach 6 later this year.
Joseph Vogel, Boeing X-51A programme manager, Advanced Network and Space Systems, and Charles Brink, X-51A programme manager, USAF Research Laboratory, spoke to reporters at Boeing's Huntington Beach facility in southern California on 14 May. They said that the consortium running the programme – USAF, Boeing, DARPA and Pratt & Whitney Rocketdyne – had recently completed testing a "flight-like" ATACMS engine (SJX-61-1) at Mach 4.6 to 5 and that the first of four flight trials of the unmanned vehicle would take place in October or November.
The first flight test X-51A (FTV-1) – which comprises (from front to back) a cruiser vehicle and scramjet engine with a separate stage solid rocket booster with control surfaces – will be dropped from the wing of a B-52 bomber at about 50,000 ft at Mach 0.8 over Naval Air Weapons Station Point Mugu in California. The booster rocket will then fire the vehicle to about Mach 4.7 and 60,000 to 65,000 ft before the scramjet engages. Once the scramjet is engaged, the rocket booster will fall away and the cruiser section will climb to between 80,000 and 85,000 ft before accelerating to Mach 6.