Fighter Jet Crashes in Test Flight : Edwards: The X-31 experimental plane goes down in Mojave desert. Pilot ejected and was apparently not harmed.

An advanced experimental fighter jet, one of only two in existence, crashed in the Mojave desert and was destroyed Thursday, but the pilot ejected and was apparently unharmed, NASA reported.

The plane was an X-31, under development jointly by the United States and Germany.

Karl Lang, a German government pilot who is one of only six X-31 test pilots, was returning from a research flight when the accident occurred, said Air Force Maj. Janet Reese.

Lang, who parachuted from the plane, “was up and walking, but he was sent to the (base) hospital as a precautionary measure,” Reese said.

The cause of the crash is under investigation, she said.

The plane crashed in an unpopulated desert area just north of the air base near California 58 and Clay Mine Road at about 2:30 p.m., said Kern County Fire Department spokesman Dennis Walker.

The single-seat, single-engine X-31, which is 43 feet long with a wingspan of 24 feet, was developed jointly by Rockwell International Corp. and a German partner, Deutsche Aerospace, formerly Messerschmitt-Bolkow-Blohm.

It is equipped with an advanced thrust vectoring system featuring three paddles, or vanes, that deflect the engine exhaust to allow the plane to make extremely fast turns, or to point sharply away from its direction of flight without stalling.

X-31 flight test operations began at Rockwell Aerospace facility in Palmdale in 1990. On its first test flight in October of that year, the X-31 reached speeds of 340 m.p.h. and an altitude of 10,000 feet, officials said.

In February of 1992, X-31 testing moved to the National Aeronautics and Space Administration’s Dryden Flight Research Center at Edwards. There was only about a month left of the testing program, said NASA spokesman Don Nolan.

Although the current status of the test program was not revealed, in April officials announced plans to gradually remove the X-31’s vertical tail fin, using the vanes to take over the functions normally controlled by conventional tail surfaces. Tailless military planes should be harder to detect on radar, engineers say.

The two X-31s were to have flown at supersonic speeds late last year. Although planes such as the B-2 stealth bomber already fly without tails, they do not reach supersonic speeds. All existing supersonic planes have tails, program officials said.