The National Aeronautics and Space Administration conducted a third and final test flight of the unmanned X-43A aircraft, which uses an experimental scramjet engine designed to push the craft to nearly 10 times the speed of sound.
A scramjet differs from conventional jet technology by not using rotor blades to compress the air inside the engine. Instead, the scramjet, sometimes called an “air-breathing” engine, burns hydrogen fuel in a stream of fast-moving, compressed air created by the forward motion of the aircraft.
Hot exhaust shooting out of the back of the jet propels it forward at high speed.
At a post-flight news conference Tuesday, mission managers said they had only begun to look at the data, but they believed the aircraft reached a speed of about 6,600 miles (10,621 kilometers) per hour, or about Mach 10.
The flight took place over the Pacific Ocean off the coast of Southern California, in restricted U.S. Naval airspace.
The black X-43A, fastened to a larger, white booster rocket, was carried to 40,000 feet (13,157 meters) strapped to the right wing of a B-52, which took off from NASA’s Dryden Flight Research Center in Edwards, California.
The B-52 released the booster rocket, which dropped for several seconds with the X-43A attached to its nose, then ignited and ascended to 110,000 feet (36,184 meters). At that point, the scramjet engine fired and the booster rocket dropped away.
As planned, the test flight lasted only a couple of minutes and ended when the aircraft ran out of fuel. It eventually crashed harmlessly into the ocean.
The test flight was originally scheduled for Monday, but technical glitches forced NASA to postpone it for 24 hours.
Tuesday’s flight was the last of three test flights in NASA’s eight-year, $230 million Hyper-X program, designed to help develop a new generation of spacecraft that could fly into low Earth orbit at a fraction of the current cost.
Some engineers have even speculated that scramjets could one day power a fleet of hypersonic airplanes, capable of crossing a continent in less than an hour. The technology also has military applications, with the potential for new innovations in ballistic missiles.
Scramjet technology could eliminate the need to use heavy liquid oxygen to launch spacecraft and rockets into orbit. A speed of Mach 25, or 17,000 miles (27,200 kilometers) per hour, is needed to lift a craft into orbit.
In 2001, the X-43A’s maiden flight ended unsuccessfully after an onboard booster rocket misfired and flight controllers had to destroy the aircraft. But last March, its second flight was successful, reaching almost Mach 7.
However, with NASA now dedicating the bulk of its resources to returning the space shuttle fleet to flight, completing construction of the international space station and developing technology for manned missions to the Moon and Mars, no additional scramjet flights are on the drawing board.