The US Air Force Research Laboratory (AFRL) has pushed back first flight for the Boeing X-51A WaveRider to February, a four-month delay caused by the unavailability of the B-52 launch platform.
The Mach 6, hypersonic vehicle completed a captive carry test under the B-52 wing on 9 December. The X-51A was stored on the inboard pylon of the left wing.
The AFRL also plans to conduct a full dress rehearsal, lacking only the planned 5min powered flight of the X-51A, in January.
Four test flights of the X-51A are scheduled within three months of the first flight event. The AFRL wants the flight-test data to justify a decision to launch a follow-on development programme, perhaps resulting in a near-term technology spin-off such as a hypersonic cruise missile.
The X-51A will achieve hypersonic velocity in three stages. First, the B-52 will jettison the X-51A at 50,000ft (15,240m) at subsonic speed. A solid rocket booster will accelerate the X-51A to Mach 4.5. Finally, a Pratt & Whitney Rocketdyne supersonic combustion ramjet will ignite for 5min, propelling the vehicle to near or over the Mach 6 mark.