Caltech Has a Space Plane ‘Skunk Works’ : Science: Students, professors and Rockwell staff join in a low-budget effort to test parts of the proposed craft.
In a remote attic laboratory at Caltech, America’s once lavishly funded space program is coping with a difficult new austerity.
A crew of professors, graduate students and scientists from Rockwell International last week began operating a 40-ton scientific instrument called a hypersonic shock tunnel in order to test parts of the National Aero Space Plane.
They needn’t rush. There’s no money to build the craft anyway.
Intended to fly like an airplane into orbit at 17,000 miles per hour, the space plane is supposed to be a centerpiece of the U.S. space program. But congressional budget cuts scuttled hopes earlier this year that Rockwell and a team of four other aerospace firms could build a flying test craft by the mid-1990s.
The intent now is to study the technology and reduce technical risks, said Barry Waldman, Rockwell’s national program director. As a result of the cutbacks, Rockwell stopped construction of a massive shock tunnel and instead helped fund the smaller tunnel in the Caltech attic.
“We have actually been on a ramp downward in terms of funding for the last couple of years,” Waldman said. “Recognizing the budget realities at the present time, we are not even asking for permission to build a flight vehicle.”
The congressional funding slowdown has also partially throttled research into hypersonic flight in the United States, which faces competition from Europe and Japan in the field.
“We are losing momentum, there is no doubt,” Waldman said. “But our competitors have too. The programs all around the world are going through the same slowdown.”
All of the nations underestimated the technical difficulty of building a space plane, said Jim Arrington, the program’s principal deputy at the National Aeronautics and Space Administration. The U.S. craft will be much larger, heavier and more costly than originally anticipated, he said.
Originally conceived as a $5-billion program, it now looks like it will cost roughly double that amount, Arrington said. So far, NASA and the Pentagon have jointly spent $1.5 billion on the effort.
At $10 billion, the space plane would be the most costly experimental vehicle ever built, but proponents assert that it is necessary if the U.S. intends to be a leader in space exploration. Unlike a rocket, which must battle gravity as it shoots straight up into orbit, a space plane would efficiently fly on wings up to the edge of the atmosphere, then make the transition into Earth orbit.
The goal, eventually, is for such planes to ferry cargo and astronauts into space.
Although the Bush Administration made no formal decision to restructure the program, the budget cuts imposed a de facto delay in building space planes. The program had anticipated $305 million in funding this year, but that was cut by a third, Arrington said. Even at the lower rate of spending, he said, the program is making important progress in developing hypersonic technology.
But in many cases the work is proceeding on a more modest track. Rockwell was building a much more ambitious shock tunnel at its test facility in the Santa Susanna Mountains, but it put that project on hold. Originally conceived as an $18-million effort, the cost grew so much that Rockwell couldn’t afford it alone, Waldman said.
The Caltech shock tunnel cost $4.35 million, of which Rockwell paid $1.5 million.
Despite the modest cost, it is the most capable shock tunnel in the United States, said Hans Hornung, director of Caltech’s graduate aeronautical laboratories. Under Hornung’s thrifty supervision, the tunnel uses a 25-horsepower scuba-gear compressor to pressurize tanks that feed the tunnel air.
When all the conditions are set, the compressed air sends a 250-pound aluminum piston down a steel tube at the speed of sound. Gases in front of the piston are squeezed until the piston breaks a steel diaphragm and accelerates up to 25 times faster.
The shock tunnel will be used to test key parts of the space plane’s supersonic ramjet engine, which has no moving parts. The engine will scoop up oxygen from the atmosphere for its ride into space, unlike existing rockets, which must carry liquid oxygen.
Germany has begun operating a shock tunnel that operates at twice the pressure of Caltech’s, but it has encountered significant technical problems, Hornung said.
