NOSEWHEEL STEERING TEST
A computerized nosewheel steering system will be tested during the flight of 61-A after Challenger lands and while it rolls to a stop at the Edwards Air Force Base lakebed.
The test is one of a series to develop nosewheel steering for all Shuttle orbiters. Currently, right and left wheel brakes are applied to steer an orbiter during landing rollout, sometimes causing excess brake and tire wear.
After Challenger’s nosewheel touches the ground, Commander Hartsfield can depress the right or left rudder pedal, signaling the computer to direct a hydraulic actuator to turn the nosewheel and steer the spacecraft onto the center line.
When Challenger slows to about 115 mph, Hartsfield will steer the vehicle off the center line about 20 or 30 feet. And then back onto the centerline before Challenger comes to a complete halt.
The activity to perfect nosewheel steering was initiated after the flight of 51-D last April when brakes locked and an inboard tire blew out on the right main landing gear during rollout.
The landing of mission 51-D on Kennedy Space Center’s runway during crosswinds and gusts of 8 to 12 knots required heavy braking to hold the centerline during rollout, contributing to the brake damage and blowout.
Edited by Richard W. Orloff, 01/2001/Page 24