Programme set back by late decision to redesign vehicle with dual-redundant systems

Northrop Grumman is building up to the delayed first flight of its X-47A Pegasus unmanned combat air vehicle (UCAV) demonstrator, a precursor to the US Navy and Defense Advanced Research Projects Agency (DARPA) UCAV-N programme. It is under pressure to fly the X-47A, and this has increased following the 22 May first flight of Boeing's X-45 UCAV demonstrator for the parallel US Air Force programme.

"We will not fly before we are ready," says Northrop Grumman X-47A programme manager Dave Mazur. "We are finishing test and integration work, and software coding is complete." The X-47 was due to fly in December last year, but was delayed after a late decision to redesign the UCAV with dual-redundant systems. A triplex system could also be used, says Mazur.

Following an initial flight readiness review with DARPA and the navy in mid-May, Northrop Grumman is preparing for taxi tests this month at the Naval Air Weapons Center, China Lake, California. Starting at 3kt (5.5km/h) these will be increased to 80kt before a first flight decision is taken.

The first flight plan includes rotation at 110kt, climb to 3,300ft (1,000m) and return for landing with an initial 2.4° glide slope. During testing, which is expected to cover up to 40 landings and around 15 flight hours, the approach angle will be gradually increased to 4°.

Increasing approach angle is key to Northrop Grumman's risk-reduction exercise for the forthcoming UCAV-N Phase II, a request for proposals for which is "due any day now", says Mazur.

"Our primary objective is to demonstrate carrier operability to mitigate risk for the next phase," Mazur adds. Northrop Grumman will bid for Phase II against Boeing, with DARPA scheduled to select the winner in 2004.

The navy plans to place the UCAV-N into full-scale development in 2007, with operational deployment for surveillance and reconnaissance aimed at 2015.

Further risk-reduction work is being performed using a company-owned Beech Baron. This "surrogate" aircraft hosts the X-47A's datalink and avionics systems. Two of three series have been completed, says Mazur. Before X-47 flies, the last software version will be flown in the Baron "with the full taxi and full take-off profiles in it".

Source: Flight International