NASA's X-43A Hypersonic Aircraft Ready For Flight
Washington - Mar 26, 2004
A pilotless X-43 plane-spacecraft hybrid is set to break jet air speed records over California this weekend, NASA said Friday.
The 3.6-meter-long (12-foot-long) craft will be dropped from the wing of a modified B-52 bomber over the Pacific Ocean to fly briefly under its own power at seven times the speed of sound, or Mach 7.
Saturday's flight is expected to be the first time a non-rocket engine has powered a vehicle at hypersonic speed.
But the trial must be run under ideal weather conditions to optimize chances for success, a flight official told AFP. A first trial in 2001 saw the loss of a prototype.
"The weather conditions look good, the weather front is clearing out, the conditions look excellent. The weather at the launch altitude is the concern and of course things could change, but we don't expect so," NASA Public Affairs Officer Alan Brown told AFP.
The trial is slated for 12:00 noon California time (2000 GMT).
NASA had announced earlier that it would push back the test to Sunday because of heavy winds.
The X-43 will be hitched beneath the wing of a B-52 bomber. Once released by the B-52, a rocket will power the prototype to an altitude of 30,000 meters (98,400 feet). Then the craft will separate from the rocket and fly on its own at seven times the speed of sound, around 7,700 kilometers (4,780 miles) per hour.
The solo flight of the X-43 was scheduled to start at 2100 GMT and last about six minutes during which it will do a series of maneuvers before plunging into the ocean.
NASA will film the trial.
"You'll see the takeoff of the B-52 from Edwards Air Force Base and its climb out and there will be a chase plane with a television camera on it," Brown said.
"When the launch actually occurs, we'll have a camera view from one of the chase planes that is flying alongside and slightly to the rear," he said.
"And they will get the dropping, the X-43 and the booster rocket that will drop away from the B-52. We should get the ignition of the rocket and its acceleration forward and its pitching up. At that point, we are probably going to lose it, because it will outrun the chase planes -- seriously."
Brown said NASA was "trying to arrange to utilize some other aircraft that are not NASA aircraft, that have some very specialized type of camera equipment, visual and infrared, to be able to track the vehicle as it is flying at very high altitude.
"We don't know if we'll be able to release that footage publicly. It's an army aircraft, it's not from a satellite."
The X-43 on paper has a top speed of 10,000 km/h but it will not be trying to reach that speed during the trial flight.
The "scramjet" technology seeks to launch air-breathing engines to ever higher altitudes without the weight oxygen canisters add, thus increasing payload capacity and eventually lowering the cost of orbital launches.
-- note: earlier today this article was issued at the time NASA had announced a flight test delay.earlier detailed report
NASA has set Saturday, March 27, for the flight of its experimental X-43A hypersonic research aircraft. The unpiloted 12-foot-long vehicle, part aircraft and part spacecraft, will be dropped from the wing of a modified B-52 aircraft, boosted to nearly 100,000 feet altitude by a booster rocket and released over the Pacific Ocean to briefly fly under its own power at seven times the speed of sound, almost 5,000 mph.
The flight is part of the Hyper-X program, a research effort designed to demonstrate alternate propulsion technologies for access to space and high-speed flight within the atmosphere. It will provide unique "first time" free flight data on hypersonic air-breathing engine technologies that have large potential pay-offs.
Hyper-X is inherently a high-risk program. No vehicle has ever flown at hypersonic speeds powered by an air-breathing scramjet engine. In addition, the rocket boost and subsequent separation from the rocket to get to the scramjet test condition have complex elements that must work properly for the mission to be successful.
The $250 million program began with conceptual design and scramjet engine wind tunnel work in 1996. In a scramjet (supersonic-combustion ramjet), the flow of air through the engine remains supersonic, or greater than the speed of sound, for optimum engine efficiency and vehicle speed.
A scramjet operates by supersonic combustion of fuel in a stream of air compressed by the high forward speed of the aircraft, as opposed to a normal jet engine, in which the compressor blades compress the air. Scramjets start operation at about Mach 6, or six times the speed of sound.
There are few or no moving parts in a scramjet engine, but achieving proper ignition and combustion in a matter of milliseconds proved to be an engineering challenge of the highest order. After a series of successful wind tunnel tests, however, NASA is ready to prove that air-breathing scramjets work in flight.
This will mark the first time a non-rocket, air-breathing scramjet engine has powered a vehicle in flight at hypersonic speeds, defined as speeds above Mach 5 or five times the speed of sound.
Researchers believe these technologies may someday offer more airplane-like operations and other benefits compared to traditional rocket systems. Rockets provide limited throttle control and must carry heavy tanks filled with liquid oxygen, necessary for combustion of fuel.
An air-breathing engine, like that on the X-43A, scoops oxygen from the air as it flies. The weight savings could be used to increase payload capacity, increase range or reduce vehicle size for the same payload.
The X-43A will fly in the Naval Air Warfare Center Weapons Division Sea Range over the Pacific Ocean off the coast of Southern California. After booster burnout, the 2,800-pound, wedge-shaped research craft will separate and fly on its own to perform a preprogrammed set of tasks.
After an approximate 10-second test firing of the engine, the X-43A will glide through the atmosphere conducting a series of aerodynamic maneuvers for up to six minutes on its way to splashdown.
This will be the second flight in the X-43A project. On June 2, 2001, the first X-43A vehicle was lost moments after release from the wing of the B-52. Following booster ignition, the combined booster and X-43A vehicle deviated from its flight path and was deliberately destroyed.
Investigation into the mishap showed that there was no single contributing factor, but the root cause of the problem was identified as the control system of the booster.
For this flight, the B-52 will carry the booster with the attached X-43A to at least 40,000 feet before its release, versus the 24,000 feet of the first attempt. This will help reduce atmospheric loads on the booster's control surfaces. The booster will carry the X-43A research vehicle to approximately the same test conditions -- altitude and speed -- as planned for the first flight.
NASA's Langley Research Center, Hampton, Va., and Dryden Flight Research Center, Edwards, Calif., jointly conduct the Hyper-X program. ATK-GASL (formerly Microcraft, Inc.) of Tullahoma, Tenn., built both the X-43A aircraft and the scramjet engine, and Boeing Phantom Works, Huntington Beach, Calif., designed the thermal protection and onboard systems. The booster is a modified first stage of a Pegasus rocket built by Orbital Sciences Corp, Chandler, Ariz.
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Washngton - Mar 22, 2004
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