LOS ANGELES – An unmanned NASA jet screamed into the record books high over the Pacific Ocean by reaching speeds of almost 7,000 mph, brightening hopes that humans might one day be able to fly across a continent in minutes instead of hours.
The 12-foot-long X-43A (search) supersonic combustion ramjet — or scramjet (search) — flew on its own power for just 10 seconds after separating from a booster rocket, but it was enough to excite researchers.
"We've given industry and government a lot of confidence to go forward with hypersonic flight," said Joel Sitz, the X-43A project manager at Dryden Flight Research Center (search) on Edwards Air Force Base. "I think that technology definitely has a future."
Initial data indicated the aircraft flew at about Mach 9.6 — or nearly 10 times the speed of sound — said Randy Voland, the scramjet propulsion team leader from NASA's Langley Research Center (search) in Virginia.
"We can really do this stuff," he said.
The X-43A was mounted on a Pegasus rocket and carried aloft by NASA's B-52 carrier aircraft to a range off the Southern California coast. At 40,000 feet, the Pegasus was released and ignited, soaring to high altitude and a speed of Mach 9.8 before the X-43A separated and flew on its own at an altitude of 111,000 feet.
"It's 90 seconds of terror, but once it's over with you realize that you've really accomplished some great things," Sitz said.
After 10 seconds of scramjet-powered flight, the X-43A became a glider and made a controlled glide to a splashdown in the ocean about 800 miles offshore. It will not be recovered.
Although brief, the flight produced an enormous amount of data compared to the milliseconds of data that all Mach 10 ground tests have produced, Voland said.
"They only add up to a second or so, maybe," he said.
The flight was the last in a $230 million-plus program to test a technology most likely to be initially used to power missiles or in military aircraft, such as bombers that could reach any target on Earth within two hours of takeoff.
Scramjets may also provide an alternative to rockets for space launches. Sitz said he believes the technology eventually can also be used for commercial passenger flights.
"We're just going to have to wait a while," he said.
Unlike conventional jet engines which use rotating fan blades to compress air for combustion, the X-43A has no such rotating engine parts. Instead it uses the underside of the aircraft's forebody to compress air for mixing with hydrogen fuel. The airflow through the engine remains supersonic.
The X-43A launched Tuesday was the last of three built for NASA's Hyper-X program.
The first X-43A flight failed in 2001 when the booster rocket veered off course and was destroyed. The second X-43A successfully flew in March, reaching Mach 6.83 — nearly 5,000 mph — and setting a new world speed record for a plane powered by an air-breathing engine.
That was more than double the top speed of the jet-powered SR-71 Blackbird (search) spyplane, which at slightly more than Mach 3 is the fastest air-breathing, manned aircraft.
Not having to carry oxygen is one of the advantages scramjets hold over rockets. Rockets achieve the same kind of high speeds but the weight of oxygen tanks or other oxidizers reduces the amount of payload they can carry.