Space.com (May 27, 2010)
"An experimental aircraft has set a new record for the longest hypersonic flight after streaking across the sky Wednesday for more than three minutes while flying at Mach 5 – five times the speed of sound — the United States Air Force has announced.
"The vehicle, called the X-51A Waverider, dropped from a B-52 Stratofortress mother ship while flying over the Pacific Ocean just off the southern California coast. It successfully ignited an air-breathing scramjet engine than accelerated up to Mach 5, Air Force officials said in the announcement.
"The entire test flight lasted just over 200 seconds, more than 10 times longer than the previous hypersonic record (just 12 seconds) set by NASA's X-43 vehicle in 2004...."
200 seconds is three and a third minutes: Which doesn't sound like much, until you start thinking about the forces at work. Remember the Wright Brothers' first flight? That lasted 59 seconds. These days, taking a little less than a minute to go 852 feet in an airplane would be anticlimactic. In 1903, it made history.
Back to that Space.com article. They defined some terms - which doesn't always happen in news coverage:
"...Hypersonic flight, typically defined as beginning at Mach 5, is more challenging than supersonic flight at lower speeds because of the higher temperatures and pressures involved with the faster flight speed. The speed of sound, Mach 1, is about 760 mph (1,223 kph) at sea level.
"Conventional turbine jet engines can't handle such speeds, Air Force officials said.
"But scramjets, air-breathing jet engines driven by supersonic combustion, like the one on X-51A have their own challenges too. Air Force project officials compared it to 'lighting a match in a hurricane and keeping it burning.'..."
This time around, they kept that match burning for over three minutes. It won't get anybody from New York to Los Angeles - or low Earth orbit - but I think that's coming.
- "X-51 Scramjet Test: This Month?"
(May 18, 2010)
- "Hypersonic Transports: Not Yet, But They're Coming"
(March 30, 2010)
- A few modifications, and these could 'fly' to orbit and back
- "X-51 Waverider, Bullet Trains: Change Happens"
(March 11, 2010)
- "Hypersonic Vehicles: Waveriders to Space"
(November 2, 2009)