DETERMINING THE NEEDS FOR SPEED OFFICIALS SEEK APPLICATIONS FOR SCRAMJET ENGINE.

Byline: Jim Skeen Staff Writer

EDWARDS AIR FORCE BASE - Pleased with the success of the final X-43A flight, program officials are looking at ways to advance hypersonic research toward future spacecraft, globe-traversing planes and ultra high-speed missiles.

The Nov. 16 flight showed the promise of the scramjet technology when such an engine powered, albeit briefly, an unmanned experimental plane at speeds of about 6,600 mph - a world record for air-breathing (nonrocket) engines.

``Breaking speed records with this new scramjet technology is very exciting for us,'' said George Orton, Phantom Works manager for hypersonic design and application. ``But the true importance of these pioneering flights is that we're learning some important lessons that we can apply to aerospace systems of the future.''

Boeing Co.'s Phantom Works, which designed the X-43, its thermal protection systems and flight control and navigation systems, is at work on Defense Department programs to advance scramjet technology.

The final X-43A flight provided actual flight data for an engine type that has been tested on the ground at ultrahigh speeds for just milliseconds at a time.

Unlike conventional jet turbine engines, a scramjet uses its interior shape, rather than moving parts, to compress the air passing through it before it is ignited.

By drawing oxygen for combustion from the atmosphere rather than carrying it as a rocket ship does, a scramjet-powered spacecraft or ultra-high-speed aircraft could save fuel weight and carry more equipment.

``This thing packed a whole lot of flight testing in a short period of time,'' said Harvey Schellenger, the Phantom Works X-43 program manager. ``It was a wind tunnel in the sky. We got data where we had no data before.''

In addition to actual hard data, the X-43 program is a model for other programs to examine in terms of how to form a seamless team with members from different contractors and different NASA research centers.

One program that can benefit from the X-43A research is the scramjet engine demonstrator waverider, which Boeing's Phantom Works and engine company Pratt and Whitney are working on for the Air Force Research Laboratory.

The flight tests would be conducted in a similar fashion to the X-43A - each waverider aircraft would be carried aloft by a B-52 and released. The aircraft would be powered by a rocket booster before the scramjet engine would be fired.

``The scramjet waverider is a step closer to something operational,'' Schellenger said. ``They would be starting the engine at a lower Mach number and then accelerate the airplane to Mach 6 or Mach 7.''

The program, valued at approximately $140 million, calls for a series of flight tests in 2007 or 2008 involving different scramjet engines.

The Air Force Research Laboratory envisions scramjet engines powering space-launch systems that can substantially reduce the cost of access to space and deliver aircraftlike operations.

Laboratory officials also see scramjets powering military and commercial aircraft that can span the globe in less than a few hours, and hypersonic missiles that can fly hundreds of miles in minutes.

Another program that could benefit is the hyfly hypersonic missile demonstrator, an effort by the U.S. Navy and Defense Advanced Research Projects Agency. The ultimate goal of the program is to demonstrate a vehicle range of 600 nautical miles with a maximum sustainable cruise speed in excess of Mach 6, about 4,200 mph.

A number of major hurdles remain before the technology could be used in an operational aircraft or missile, including finding ways for the engine to change its shape as it goes through different flight conditions.

Another hurdle is in making the transition from a turbine jet that takes the vehicle up to a certain point, from which the scramjet would operate and then slow back down again when it comes time to land.

None of the challenges is technically impossible, but progress will likely be done in baby steps rather than in large leaps.

``It's going to require a considerable investment,'' Schellenger said. ``It's not to the point to get industry to step up.''

If given his choice, Schellenger said he would like to see NASA revisit the X-43 follow-on efforts that were canceled in the wake of the agency's new initiative to go back to the moon. During a review of programs, NASA officials determined that hypersonics would not play a role in the new initiative and dropped efforts for an X-43B and an X-43C, which actually would have been developed first.

The proposed X-43B would have used a scramjet engine for up to five minutes. The B model would have had all of its propulsion components inside the airplane, rather than requiring a booster rocket. The aircraft would have been capable of reaching speeds of 5,000 mph and then landing on a runway.

The X-43C, conceived after the X-43B, was envisioned as a steppingstone between the A and B models. Plans for the C model called for a 16-foot-long airplane, four feet longer than the X-43A, and the use of a different scramjet engine, one that used a hydrocarbon fuel rather than gaseous hydrogen as in the X-43A.

Hydrocarbon fuels are much denser than hydrogen, allowing an engine test time measured in minutes rather than the seconds available with the X-43A.

``Let's go back and tune up and reactivate that approach,'' Schellenger said.

Although the effort was canceled, Schellenger said that the idea is not completely dead and that the success of the X-43A effort might re-energize its proponents.

In early 2005, NASA will unveil its proposed 2006 budget - a budget that advocates hope will include a follow-on hypersonics research project. X-43 program officials said there is a proposal ``in the selling stage'' within NASA to look at developing scramjet technology as the first stage of a two-stage space launch system.

While being noncommittal toward future hypersonics plans, senior NASA officials have praised the successes of the X-43 program.

``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,'' said NASA Administrator Sean O'Keefe.

Jim Skeen, [phone]

james.skeen(at)dailynews.com

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2 photos

Photo:

(1 -- 2 -- color) This X-43 scramjet, above, at Edwards Air Force Base, is made to be attached to a Pegasus rocket for launch, top, ultimately reaching speeds of Mach 10.

Gene Blevins/Special to the Daily News