NASA's unmanned X-43A "scramjet" broke the aircraft speed record for the second time this year yesterday, streaking flawlessly across clear blue Pacific skies at nearly 10 times the speed of sound to reaffirm the dream of "hypersonic" flight.
"What I can say is it looked really, really good," Randall T. Voland, senior research leader for the mission, said in a television news conference after the flight.
Flight controllers, speaking from NASA's Dryden Flight Research Center in Edwards, Calif., said the rocket-assisted flight came off without a hitch. The X-43A's scramjet engine ignited and fired at an altitude of 111,000 feet for about 10 seconds to achieve speeds of Mach 9.8 which NASA said amounted to 7,000 mph, according to preliminary calculations.
The flight was the last in NASA's Hyper X program, a demonstration project to show that air-breathing crafts can reach "hypersonic" speeds in excess of Mach 5 (3,800 mph). In March, NASA claimed the air speed record when it flew a scramjet at 5,200 mph.
Researchers in the U.S. armed forces and several countries are working on scramjets as a low-cost alternative to rockets in weapons such as cruise missiles, and as an intermediate stage in spacecraft launches. Unlike rockets, scramjets do not need to carry their "combuster" with them, potentially a huge savings in weight and cost.
NASA has no plans for further scramjet missions, but project manager Joel Sitz noted that yesterday's flight produced data that "have given industry a lot of confidence to go forward."
The black 12-foot scramjet, perched atop a Pegasus rocket booster, was lifted into the sky yesterday slung below the wing of a B-52 bomber.
At 2:35 p.m. (5:35 p.m. EST), the B-52 dropped the Pegasus and its passenger from an altitude of about 40,000 feet. Five seconds later the booster ignited, and the rocket shot up like a meteor, trailing a wake that gleamed green and lavender in the afternoon sky.
As the aircraft disappeared from sight and camera, flight controllers monitoring the aircraft's radio signals reported both rocket and booster functioning perfectly through the 90-second burn, release of the booster and the opening of the X-43A's scooplike nose.
Ten seconds later it was over, and the scramjet began a 10-minute downward glide to plunge to a watery grave more than 800 miles out to sea. The booster fell into the ocean separately.
Scramjets, short for "supersonic combustion ramjets," work the same way as all jet engines by igniting fuel in compressed air and aiming the expanding gases to the rear. The difference in scramjets is that the air passing through it travels at supersonic speeds.