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Fast Times at 12 O'Clock High: 5,000 MPH

March 28, 2004|Peter Pae | Times Staff Writer

EDWARDS AIR FORCE BASE — A 12-foot-long unmanned experimental aircraft equipped with a special jet engine streaked across the Pacific Ocean at more than seven times the speed of sound Saturday, shattering a technology barrier and brightening prospects for super-fast airline flights.

Flying faster than any other aircraft ever built, NASA's X-43A "Hyper X" plane reached a top speed of about 5,000 mph, or about a mile and a half per second, before being intentionally ditched in the ocean.

The previous record for a jet aircraft was held by the SR-71 spy plane, which reached speeds of 2,100 mph.

The X-43A also surpassed the Mach 6.7 speed record set by the X-15 rocket-powered plane in 1967. An aircraft traveling at Mach 1 is flying at the speed of sound, which is about 720 mph, depending on atmospheric variables.

The world's fastest flight came after five decades of research fraught with frustrations and setbacks.

For a while, aerospace analysts asserted that developing a jet plane that could reach hypersonic speeds -- exceeding five times the speed of sound -- would be harder to accomplish than sending a man to the moon.

A successful flight, they said, would be akin to the breaking of the sound barrier more than 55 years ago.

"It worked wonderfully," said Joel Sitz, project manager for NASA's X-43A program at Edwards' Dryden Flight Research Center. "Today was a grand slam in the 12th inning."

"Everything went as planned," Sitz said.

The hypersonic flight lasted only about 11 seconds, but it demonstrated a technology that could one day produce an airliner that would fly from Los Angeles to Tokyo in two hours.

"It's a big step forward for aerospace technology," said Charles Vick, a senior fellow at GlobalSecurity.org, an aerospace research firm.

The successful flight, two years after the failure of the first attempt, is also likely to bolster efforts to expand development of jet technology. Since President Bush announced an initiative this year to go to the moon and to send astronauts to Mars, many of NASA's aeronautical research efforts have been in jeopardy.

"A lot was riding on this flight," said Vincent Rausch, program manager for NASA's hypersonic research.

In June 2001, NASA officials destroyed a nearly identical plane after its booster rocket fell apart shortly after launch.

NASA officials felt they could not afford another failure.

The Pentagon scuttled a more ambitious effort launched during the Reagan era to develop a hypersonic aircraft for more than $2.5 billion.

In 1997, NASA decided to launch a more modest development project, an initiative propelled by the military's interest in super-fast aircraft and by calls for more affordable ways to lift vehicles into space.

Under a $230-million program, NASA engineers built three X-43A aircraft. The 2001 test resulted in the destruction of one.

The hypersonic plane, resembling a boogie board with twin tail fins, was propelled by a supersonic combustion ramjet engine, or "scramjet," essentially a rectangular copper box mounted on its belly.

The simplicity of the design belies the difficulty of the technological barrier it has overcome.

The common turbojet found on most commercial and military aircraft uses turbines inside the engine to compress air, which ignites with kerosene to create combustion and then thrust. But air flows too slowly and the engine overheats at high speeds. Engineers figured out a way to resolve the heat problem by developing the ramjet -- basically a hollow tube with no moving parts.

Air flows into the front of the ramjet, is compressed and then is mixed with fuel. The resulting combustion creates thrust. But the ramjet cannot power an aircraft past Mach 5. That required the development of the scramjet, in which gases flow into the chamber at supersonic speeds.

Although the engine seems mechanically simple, it is vastly more complex aerodynamically than other jet engines. The aircraft had to be designed so that the front end of the X-43A -- its flat nose -- helps to compress the oxygen before it enters the copper alloy chamber, where it mixes with hydrogen and burns, creating pressure from the expanding gas to propel the plane forward.

To get up to the hypersonic speed, it needs to suck in enough oxygen to create combustion and then thrust. It needed help from an Orbital Science Corp. Pegasus rocket to kick-start its engine.

In a beginning reminiscent of the notable X plane experiments during the heyday of aerospace test flights here, a modified B-52 bomber took off with the rocket attached to its wings, flying to 40,000 feet about 50 miles southwest of Los Angeles.

Two F-18B chase planes followed the B-52 and transmitted live video images to nervous NASA officials watching from a flight operations room at Dryden Flight Research Center based at Edwards.

As the B-52 neared San Nicolas Island, the booster detached from the wing and began a five-second free-fall before the rocket engines ignited.

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