NASA - National Aeronautics and Space Administration

According to the comic books, Superman could fly "faster than a speeding bullet." That's nothing. The SR-71 Blackbird reconnaissance plane set a jet speed record of Mach 3.2, more than three times faster than the speed of sound. The X-15 rocket plane set a record for winged vehicles with a speed of Mach 6.7. They're both slowpokes.

Image to left: The X-43 is also referred to as the Hyper-X. Credit: NASA

NASA surpassed both of those records earlier this year with a new airplane called the X 43A, also known as the Hyper-X. In March 2004, the Hyper-X set a new record for air-breathing aircraft of about 5,000 miles per hour (mph), or nearly seven times the speed of sound. But, now, even that record has been left in the dust. In fact, the new record holder reached a speed almost as great as the records of the Blackbird and the X-15 put together. Now, that's fast.

In November 2004, the X-43A flew for the final time, and set a new speed record almost 10 times faster than the speed of sound. Initial data showed the 12-foot-long unmanned plane reached about 7,000 mph, or nearly Mach 9.8, at an altitude of about 110,000 feet.

Image to right: The X-43 is an air-breathing jet. Credit: NASA

The world's first hypersonic (faster than Mach 5) jet airplane, the X-43A uses a new technology called the scramjet engine. The term scramjet is short for supersonic-combustion ramjet, and means that the plane uses supersonic air from the atmosphere mixed with fuel to propel itself. Until now, the fastest planes have reached those advanced speeds with the help of rockets. Hyper-X planes, though, are air-breathing jets. In normal turbojet engines, the compressor section (the fan blades) compresses the air to accelerate it through the engine at great speeds. That's what creates the forward movement. In rockets, fuel and oxygen are combined and burned to create the blast of energy. In air-breathing vehicles, though, vent inlets on the outside of the plane scoop the air from outside. Because the X-43A is going so fast, the air is forcefully "rammed" into the engine, which is how this type of propulsion was named ramjet.

Ramjet engines use a subsonic stream of air through the engine to create forward motion of the aircraft at supersonic (above the speed of sound) speeds. When the air flowing through the engine stays at supersonic speeds, it's called a scramjet. Scramjets and ramjets need no moving parts in their engines because the thrust is created by rapidly forcing airflow through the engine. Because air-breathing vehicles don't need to carry oxygen for fuel (as with rockets), they weigh less. Another advantage is scramjets can be throttled back and flown more like an airplane, unlike rockets, which tend to produce full thrust all the time. "This flight is a key milestone and a major step toward the future possibilities for producing boosters for sending large and critical payloads into space in a reliable, safe, inexpensive manner," NASA Administrator Sean O'Keefe said of the final Hyper-X flight.

Image to left: The X-43 is carried aloft by a launch aircraft. Credit: NASA

During the recent test flight, the X-43A was carried aloft by a B-52B launch aircraft, which was flown by pilot Gordon Fullerton and co-pilot Frank Batteas. Fullerton was already familiar with hypersonic flight, having himself reached Mach 25 as a Space Shuttle commander. The X-43A was mounted to a Pegasus booster rocket that was attached to the underside of one of the B-52B's wings. Once the B-52B had reached the proper height, it released the Pegasus rocket, which boosted the Hyper-X near to its test speed over the Pacific Ocean. The X-43A then separated from the Pegasus, and used its scramjet engine for about 10 seconds of powered flight. When the engine shut down, the "disposable" aircraft glided into the Pacific Ocean, according to plan.

The November 16 flight was the third test of the X-43A. A June 2001 test ended in failure when the aircraft had to be destroyed when it deviated from its flight path. The root cause of the problem was identified to be the control system of the booster rocket.

Image to right: The X-43 soars in the sky. Credit: NASA

The technology successfully demonstrated by the Hyper-X could someday have huge implications for both air flight and spaceflight. At the speed at which the X-43A flew, it could go from New York to Tokyo in under an hour. By avoiding a rocket's need to carry an onboard supply of an oxidizer, a scramjet engine could help carry large payloads into space more efficiently. By turning theory into reality, NASA has opened a door into the future of transportation on this world and beyond.
 
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Published by NASAexplores