10 October 1947 On Yeager’s seventh powered flight, Chuck had the X-1 at .94 Mach when his controls suddenly ceased to function. Shock waves on the plane’s control surfaces made operation impossible.
Always cool-headed in such situations, Chuck turned off the plane’s rockets to slow down and jettisoned the remaining fuel. He glided back into the lakebed and explained to Jack Ridley what had happened.
Engineers had predicted that as the plane reached the speed of sound, its nose would pitch up or down. At .94 Mach, however, Chuck had lost the ability to operate the plane’s elevator. Without it, he could not correct for whatever pitch change might occur at Mach 1. It was Jack Ridley who came up with the solution.
On his seventh powered flight, Chuck had the X-1 at .94 Mach when his controls suddenly ceased to function. Shock waves on the plane’s control surfaces made operation impossible. Always cool-headed in such situations, Chuck turned off the plane’s rockets to slow down and jettisoned the remaining fuel. He glided back in to the lakebed and explained to Ridley what had happened.
Engineers had predicted that as the plane reached the speed of sound, its nose would pitch up or down. At .94 Mach, however, Chuck had lost the ability to operate the plane’s elevator. Without it, he could not correct for whatever pitch change might occur at Mach 1. It was Jack Ridley who came up with the solution.
Ridley believed it was possible for Chuck to control the aircraft using the horizontal stabilizer. Bell had built the capability into the X-1 of controlling the stabilizer’s angle of attack. Chuck and Jack Ridley gave it a thorough testing on the ground, then told Colonel Boyd they felt confident trying the method in flight.
The eighth powered flight followed the same plan as the one before. Chuck tested the horizontal stabilizer control at .96 Mach and Ridley was right. The system worked and Chuck was able to regain control of the X-1. The next flight would come after the weekend, and plans called for taking the X-1 out to .98 Mach. (2)
(1) Wikipedia
(2) Chuck Yeager “Mach Buster”