Aero Space Plane to Be Scaled Back : Funding: To save the experimental craft, the Air Force will trim its budget by two-thirds.

The Air Force will unveil next week a plan to scale back Rockwell International’s National Aero Space Plane program, abandoning the goal of reaching Earth orbit with the hypersonic craft and trimming the budget by two-thirds.

The revised plan is intended to rescue the program, long considered one of the nation’s showpieces of advanced space technology, from potential oblivion amid an erosion in congressional support that has reduced funding.

Under the new plan, the craft will fly much slower than originally intended, only between Mach 12 to Mach 15, rather than the Mach 25 necessary to fly into orbit, according to Robert R. Barthelemy, the Air Force’s program manager for the space plane.

In addition, the craft may no longer take off from a runway like an airplane, but rather be launched into flight from the back of another aircraft--much as previous generations of experimental high-speed craft have done.

The cutbacks are intended to regain control of the program’s budget, which has spiraled upward from early estimates of $5 billion. Now, the cost is put at $10 billion with little assurance that it could be completed for that amount.

The new craft will be one-third the size of the original design and cost a third or a fourth as much, putting the program cost at $2.5 billion to $3.5 billion, Barthelemy said in an interview Friday.

Rep. George E. Brown Jr. (D-Colton), chairman of the House Committee on Space, Science and Technology, said he supports the restructuring--though he characterized the new space plane as a “Model T version” and said he would rather see a somewhat more ambitious “Chevrolet version.”

“It is better to pull back and be safe,” he said. “The congressional support has been wavering. The budget is not very favorable these days for a large, uncontrolled program.”

Barthelemy said the reduced effort remains critical to U.S. leadership in advanced aerospace, because European nations are forming a consortium with Russia to pursue the technology. It was disclosed at an aerospace conference this week that France is collaborating with Russia in testing a revolutionary supersonic ramjet engine.

“I think U.S. aerospace leadership is on the line here,” he said. “If we are not the leaders in hypersonics, then we are in trouble. I don’t think that is recognized outside of the aerospace industry.”

But Heinz Pfeffer, the chief of the European Space Agency’s development programs, disputed the notion that American leadership is at stake, saying that Europe lags behind the United States and is not seeking to catch up.

Funding in fiscal 1993 for the U.S. space plane was cut from a requested level of $255 million to $150 million, undermining any hope the original goals for the space plane could be met. At its peak, the program had 3,000 workers at Rockwell and its partners Pratt & Whitney, Boeing and McDonnell Douglas. Today, the program has 1,500 workers, of which 250 are at Rockwell.

“I am disappointed but a realist,” Rockwell Executive Vice President Sam Iacobellis said. “A program that was going to require $1 billion a year in this current financial environment was going to be a hard sell.”

Still, Iacobellis said the reduced program will achieve breakthroughs in materials and propulsion technology. Ultimately, the nation will return to a goal of building a space plane that can fly from a runway directly into orbit, he predicted.

The new Air Force plan also raises new questions about longstanding reports that it is already flying a craft at speeds of Mach 8. An upcoming article in Janes Defence Weekly suggests that such a craft, built by Lockheed and Rockwell, was spotted over an oil production platform in the North Sea.

But Barthelemy said he knows of no such craft. Other experts noted that a Mach 8 craft could not operate on a ramjet engine. Rather, it would require an advanced supersonic ramjet, which has never been tested or flown, they said.

It is unclear why the Pentagon would be proceeding with the scaled-back National Aero Space Plane if an existing craft already was using a supersonic ramjet, the experts noted. Still, some type of secret craft clearly has been developed by the Air Force, experts say, based on numerous sightings around the world.