Unmanned combat aircraft operations moved a step closer on 22 May with the first flight of Boeing's X-45A unmanned combat air vehicle (UCAV) demonstrator from NASA Dryden Flight Research Center's dry lakebed at Edwards AFB, California.

The 8m (26.3ft)-long vehicle took off at 07.26 and reached 7,500ft altitude during its 14min flight, most of which was conducted at 195kt (360km/h). The undercarriage was not retracted and the vehicle "stayed in the heart of the envelope", says US Defense Advanced Research Projects Agency (DARPA) programme manager Col Mike Leahy.

A second flight of the Honeywell F124-powered X-45A is planned before the end of June, with a "major [flight control system] software upgrade between the third and fourth flights", adds Leahy. The undercarriage will be retracted for the first time on the fourth flight and envelope expansion will begin on the fifth. A second X-45A will fly later this year.

The flight follows a four-year effort by the joint Boeing, DARPA, NASA and US Air Force team. Further test flights are planned through to mid-2004. The UCAV programme will later be transferred to the USAF.

The programme includes the continuing development of the larger 11m-long X-45B which is due to fly in late 2004. Three X-45Bs are due to enter the test programme by the end of 2005.

Fabrication of the first of up to 14 production standard Block 10 versions is due to start in 2006. These will be the first initial operational versions, although Leahy says that there has been "no decision on the ultimate force size of UCAVs".

The proposed operational UCAV design, provisionally named the A-45, is being refined for a 1,200km (650nm) mission radius with a 1,635kg (3,600lb) weapons load. Planned payloads will include two external 1,140 litre (300USgal) fuel tanks, two miniature air-launched decoys, two Joint Direct Attack Munitions, an internal auxiliary fuel tank and up to 12 small diameter bombs (SDBs).

The 910kg payload X-45B will be tested with up to eight SDBs and two 450kg JDAMs.

Critical focus areas for the X-45B/A-45 "technology base" now include the development of a precision synthetic aperture radar with a conformal, low observable antenna, affordable stealthy avionics apertures and an in-flight refuelling system.

Source: Flight International