Tuesday, the Air Force will test the X-51A Waverider, an unmanned plane capable of reaching speeds fast enough to cross the Atlantic Ocean in an hour, nearly three times faster than the supersonic Concorde jet.
Called Waverider because of the way it "rides" on the supersonic sound waves it creates, the vehicle achieves dazzling speeds with what's known as a scramjet engine, which has no moving parts and sucks oxygen out of the atmosphere in order to ignite its hydrogen fuel. The result is an efficient and extremely powerful engine.
Mark Lewis, former Chief Scientist of the U.S. Air Force, says the technology is in its early stages, but the successful May 2010 test flight of nearly three minutes proved that the concept is sound. During that test, the Waverider reached speeds of Mach 5 (five times the speed of sound), about 3,400 MPH. Tuesday, it's expected to go faster than Mach 6, more than 4,500 MPH.
"It has applications all across the board: New types of weapons, aircraft and space vehicles. We could design spacecraft that could fly to space more like an airplane," Lewis says. The Waverider program was initiated under his watch. "Tuesday's is more of a technology test. If it works, its first application will almost certainly be military. Civilian high-speed aircraft is a long way away."
A second test last June was less successful and was aborted soon after it started. But even if Tuesday's test fails, Lewis says the technology should continue to be developed.
"The first test proved beyond a reasonable doubt that this propulsion technology was real and achievable and practical," he says. "If we knew it was going to work, we wouldn't have to do the flight test. We have to be allowed to fail … we know we can do it, but we have to make it more operational, more practical. It's not something we can quit."
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Tuesday's five-minute flight, Lewis says, is long enough to determine if the engine can handle the intense amount of heat generated by the hydrogen-oxygen reaction. "We're confident if we can go 300 seconds, we can go forever," Lewis says.
The project, according to Globalsecurity.org, a military analysis website, has cost about $140 million to this point. But Lewis is confident that, after jumping over a few more hurdles, the technology won't be any more expensive than standard jet engines.
"Some people think because it goes so fast, that it's going to be prohibitively expensive," he says. "In terms of military technology, it shouldn't be much more expensive than current jet engines … in principle, it's the simplest kind of engine you can imagine. It's a duct. It mixes fuel, burns it, and exhausts it out the back."
"We know we can do it, we've already done it," Lewis says. "Someone asked me if this is science fiction—well no, it's science fact."
Jason Koebler is a science and technology reporter for U.S. News & World Report. You can follow him on Twitter or reach him at firstname.lastname@example.org
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