SCRAMJET TESTING IN WINGS ENGINE MAY REVOLUTIONIZE FLIGHT.

Byline: Jim Skeen Staff Writer

EDWARDS AIR FORCE BASE - NASA is just a few weeks away from testing a very-high-speed engine that could revolutionize space flight in the same way the jet engine advanced airplane travel.

NASA is preparing the first of three Hyper-X aircraft that will test a scramjet - an abbreviation for supersonic combustion ramjet, a simple but extremely high-speed jet engine.

``We are making aviation and hypersonic history with this flight,'' said Joel Sitz, Hyper-X project manager at NASA's Dryden Flight Research Center. ``Getting to this point in history is very exciting.''

The ultimate goal of the $185 million program is to create a scramjet-powered aircraft, one that would use air from the atmosphere rather than carrying oxygen, like a rocket. The weight savings from not having to carry oxygen fuel tanks would allow an aircraft to carry more scientific or other equipment.

During the flight, scheduled for mid-May, the pilotless 12-foot-long Hyper-X, also known as the X-43A, will fire its scramjet engine for about 10 seconds before ending its mission with a crash in the Pacific Ocean.

Program officials envision an operational spacecraft, using the Hyper-X technologies, operating in 2025 to 2030. Such a spacecraft could operate more like an airplane than a rocket or space shuttle, which require more time, effort and money for a mission.

``If you can operate like an airplane, you get the safety factor up and the costs down,'' said Vincent Rausch, Hyper-X program manager at NASA's Langley Research Center in Virginia. ``What we have to look forward to is a paradigm shift similar to what the jet engine had over the piston engine.''

A scramjet is a high-altitude, very-high-speed version of a ramjet, an engine that lacks conventional jet engines' whirling fan blades for compressing air to oxidize fuel.

In a ramjet, the fuel is continuously compressed by being rammed into the inlet by the aircraft's high velocity. In a scramjet, the airflow through the whole engine remains supersonic.

The three Hyper-X aircraft will be used for three test flights - two at Mach 7, about 5,320 mph, and one at Mach 10, about 7,600 mph.

In comparison, the famous X-15 research plane of the 1950s and 1960s reached a top speed of Mach 6.7, powered by a rocket engine, not a jet engine. The jet-powered SR-71 Blackbirds flew at Mach 3.

During each mission, an X-43A attached to a Pegasus booster rocket will be taken aloft from Edwards Air Force Base by a modified B-52 bomber. The X-43A will be dropped from the B-52 off the coast near Vandenberg Air Force Base, north of Lompoc.

The Pegasus booster will hit Mach 7 and carry the X-43A to more than 100,000 feet in about 90 seconds. From there, the X-43A will separate from the booster, and the aircraft's scramjet will fire for about 10 seconds.

After the engine burn, the X-43A will perform a series of preplanned aerodynamic maneuvers before it slams into the Pacific Ocean.

``This is research; there are a lot of risks,'' Rausch said.

One of the risks is not knowing how well the X-43A will separate from the Pegasus booster. During the separation, four explosive bolts holding the X-43A to the Pegasus will fire and two pistons are designed to push the aircraft away.

Later this month, the National Aeronautics Space Administration will conduct a test in which the B-52 will carry the X-43A aloft to see how the two handle together. Provided there are no major technical glitches, the first actual flight of a X-43A would occur in mid-May. The flight tests are expected to be completed in a year.

CAPTION(S):

2 photos

Photo:

(1) Preparations are being made to test a scramjet - a supersonic combustion ramjet - with a very-high-speed jet engine.

(2) Vince Rausch, left, program manager for the Hyper-X, and Joel Sitz, project manager for the X-43 flights, talk about tests.