New Space Shuttle Brake Design Now Ready For Use: NASA Engineer
SPACE CENTER, Houston (AP) _ One improvement recommended by the Rogers commission already has been accomplished, a NASA engineer says - the shuttle will have new and more powerful brakes whenever it next returns from space.
A beryllium-based brake system used previously on the space shuttle has been reinforced and tested and is ready to fly if shuttle missions resume in July 1987, as planned, Robert Bobola, an engineer who supervised testing of the shuttle brakes and tires, said Wednesday.
By April 1988, Bobola said, an even better system of brakes, made of carbon, will be installed on the space shuttles.
In testimony Wednesday before Congress, Richard H. Truly, the NASA associate administrator for space flight, said he and Arnold Aldrich, the shuttle program director, have approved the new brake system.
In its report on the investigation of the Challenger accident, the Rogers commission said the shuttle ″tire, brake and nosewheel steering systems must be improved. These systems do not have sufficient safety margin, particularly at abort landing sites.″
Bobola said the new brake systems will safely stop the shuttle even in the sternest possible landing situation.
Failed brakes caused tires to blow out during a shuttle landing at Kennedy Space Center, Fla., in April 1985, forcing the National Aeronautics and Space Administration to abandon routine landings at Kennedy until brake and nosewheel steering systems could be improved. After one test of the nosewheel steering, Challenger was scheduled to land at Kennedy in January. The spacecraft exploded before it reached orbit.
The proposed landing of Challenger at Kennedy had been opposed by chief astronaut John Young who wrote a memo claiming the brakes, tires and nosewheel steering were inadequate for the tricky Kennedy landing and that Florida weather was unpredictable.
The Rogers commission cited Young’s position in its report.
Bobola said that beryllium stators in the shuttle brakes have been reinforced with an additional quarter-inch of metal.
Using the new brakes, he said, ″we have demonstrated one 65 million foot- pound stop.″ A braking force of about 25 million foot pounds is required for a typical shuttle landing. The April 1985 Kennedy landing, in which the brakes were destroyed, required about 40 million foot pounds because of a cross wind.
Bobola said the beryllium brakes would be used only until the new carbon brakes being manufactured by B.F. Goodrich are available in April, 1988. At that point, all the beryllium brakes in the shuttles would be replaced.
Tests of the carbon brakes, said Bobola, showed that they can endure a force of up to 82 million foot pounds.
He said more testing of tires and the Kennedy runway surface would be needed before shuttles can land routinely at the Florida center.
He said the tires usually are worn through to the third layer of cords during Kennedy landings. Part of the reason, he said, is the rough surface of the runway, which tends to chew up the tire tread at the moment of touchdown when the wheel is suddenly forced to start turning.
Engineers are studying the possibility of smoothing the runway surface at the touchdown points and leaving it rough in the center for efficient braking.
Bobola said engineers also are investigating ways to pre-spin the tires before they touch the runway. He said this could be done with wind vanes or gas jets or even a lanyard that would start the wheels rotating as the landing gear is lowered. By pre-spinning, said Bobola, there would be less friction on the tires at contact with the runway and the damage would be reduced.