McDonnell Douglas (MDC) has modified its X-36 tailless-fighter technology demonstrator after overheating cut short the 17 May first flight.

The remotely piloted research aircraft was landed after just 6min when sensors indicated high temperatures in a rear-fuselage compartment. MDC has added air scoops to improve cooling, according to X-36 programme manager Gary Jennings.

The 28%-scale X-36 was flown to 4,900ft (1,500m) and 147kt (270km/h) on its first flight from NASA's Dryden Flight Research Center, Edwards AFB, California. Although shorter than planned, the flight demonstrated the aircraft's good stability and easy handling, Jennings says. The X-36 will be flown to 160kt and 35í angle of attack in a further 24 flights, to be completed by mid-November.

The programme aim is to demonstrate the controllability of a highly agile tailless fighter. The aircraft's "significant" longitudinal and directional instability is overcome by a powerful MDC-developed flight-control computer.

The X-36 has thrust vectoring, as well as all-moving foreplanes and split ailerons and flaperons on the aft-set wing. The nozzle provides yaw control, while the ailerons function in roll and yaw.

Jennings is "absolutely thrilled" with the aircraft's handling. Compared with other fly-by-wire aircraft, control-surface activity on the first flight was minimal. "You'd be hard-pressed to see the surfaces moving, which mean we have a lot of control power available," he says.

Two X-36s have been built, with the second scheduled to be flown in June. The 575kg aircraft is powered by a 3.1kN (700lb)-thrust Williams F112, with 80kg of fuel providing a flight time of 30-45min. The remotely piloted vehicle is flown from a ground station, using a camera providing a view forward from the "cockpit" and a display showing aircraft position.

Source: Flight International