Wednesday, November 09, 2011

Drag Chute Reduced Shuttles' Brake and Tire Wear

The landing of space shuttle Endeavour on the 15,000-foot concrete runway at Edwards Air Force Base, Calif., to conclude shuttle mission STS-49 in 1992 demonstrated a new capability for the shuttle fleet. A 39-foot-diameter braking parachute was used to slow the vehicle, relieving stress on the brakes and tires and reducing the landing rollout by as much as 2,000 feet.

Engineers had initially considered such a feature for the shuttle, but eliminated it from preliminary designs in 1974 after deciding it wouldn’t be needed for planned lakebed landings at Edwards. Endeavour was the first orbiter to be built with the drag chute that would soon become a standard feature on the shuttle fleet.

In 1990, researchers at NASA's Dryden Flight Research Center at Edwards used the center's modified NB-52B to test the drag parachute system that would be used on the shuttle orbiters. In a series of eight chute deployment tests, the B-52 landed at speeds ranging from 160 to 230 miles per hour on one of the lakebed runways, as well as on the 15,000-foot concrete strip.

Instrumentation on the B-52 obtained data during chute deployments to validate predicted loads that an operational shuttle orbiter would sustain with a drag chute deployed during landing and rollout. Successful test results led to incorporation of the drag chute system on Endeavour as it was being built. The other three orbiters – Columbia, Discovery and Atlantis – were retrofitted with the system as they underwent normal periodic maintenance.

Endeavour’s first landing on May 16, 1992 was the first operational demonstration of the system. The drag chute was deployed as the nose gear touched down, and the orbiter came to a stop following a landing roll of 9,490 feet. Though this fairly typical rollout was the result of conservative mission planning, subsequent landings of Endeavour demonstrated that the drag chute could reduce landing rollouts by 700 to 1,500 feet.

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