Thread by @thehighfrontier

THREAD #OTD in 1953, Air Force test pilot Chuck Yeager set a new unofficial speed record in the Bell X-1A rocket research aircraft, reaching Mach 2.44 at an approximate altitude of 75,000 ft /1
#avgeek #aviation

…In doing so, Yeager beat the record that Scott Crossfield had set just 22 days earlier in the Navy sponsored D-558-II Skyrocket, when the NACA pilot had become the first person to exceed Mach 2. The intense rivalry between the still relatively young Air Force and the Navy.. /2

...to set a new speed record before the 50th anniversary of the Wright brothers historic flight at Kittyhawk on December 17th led to a flurry of activity out at Edwards AFB. The Air Force had hoped to reach Mach 2 much earlier than 1953, but after the first of the .../3

...advanced X-1 aircraft, the X-1D, was lost in an explosion in 1951, their efforts were delayed. Once the X-1A had been delivered, there were further delays following initial glide flights by Bell test pilot Jean ‘Skip’ Ziegler. Following Ziegler’s untimely death .../4

...in a midair explosion of the X-2 rocket plane, Yeager was assigned to fly the X-1A by ‘Pete’ Everest, then chief of flight test operations at Edwards. As the Air Force team prepared the X-1A for its assault on Mach 2, they had to watch on as Crossfield edged the lower .../5

...performing Skyrocket to twice the speed of sound. Determined not to be outdone by a Navy aircraft operated by a civilian agency, Yeager and Jack Ridley hatched a plan they referred to as “Operation NACA Weep” to significantly exceed Crossfield’s record. Based on data.../6

...from earlier X-1A flights and additional wind-tunnel testing of the design, both Bell Aircraft and the NACA warned that the aircraft was likely to become unstable beyond Mach 2.3 potentially leading to a dramatic departure from controlled flight. .../7

On December 12, Yeager dropped away from his B-29 launch aircraft and lit the X-1A’s XLR11 rocket engine. As he streaked towards his planned maximum altitude of 70,000 ft, Yeager had trouble reading his instruments due to glare within the cockpit, causing him to overshoot. .../8

At an altitude of approx 75,000 ft the X-1A easily exceeded Mach 2 and continued to accelerate. Pushing on past the recommended Mach 2.3, Yeager eventually reached Mach 2.44, but Bell’s warnings had been well founded and as the X-1A streaked onwards .../9

...through the lower stratosphere, its left wing began to dip. Yeager attempted to correct whilst also shuting down the XLR11, but the X-1A quickly departed from controlled flight and began to tumble wildly in all 3 axis. Cameras located over the wing and in the nose of the.../10

...X-1A caught the wild ride as Yeager fell approx 50,000 ft in just under a minute. In the thin air at the higher than planned maximum altitude, there had not been enough dynamic pressure on the X-1A’s control surfaces to maintain the aircraft’s directional stability. .../11

When the aircraft went out of control just as Bell had predicted, there was little Yeager could do but ride it out (the X-1A did not carry an ejection seat). Once the aircraft entered denser air at lower altitudes, it entered an inverted spin allowing the battered pilot .../12

...to recover to a regular spin, then level flight. Recordings of the incident reveal just how shaken up Yeager was as he fought to bring the aircraft back to Edwards.
(video via: W. N. Y. Launches the Space Age: The X-1A Story - Robert A. Rohrer) .../13

As the Air Force celebrated the success of Operation NACA Weep, the NACA’s female computers led by Roxanah Yancey, were hard at work crushing the numbers and determining what had actually happened above the High Desert that day. This flight represented one of the first .../14

...encounters with a phenomenon known as inertial coupling, which soon became a problem for other supersonic aircraft, including the X-2, X-3 and the NAA F-100. By straying too high and too fast, Yeager had been lucky to escape with his life, but the X-1A’s research.../15

...instrumentation had recorded the incident in detail, allowing the NACA to develop a better understanding of inertial coupling. In the aftermath of the December 12th flight, the Air Force quietly imposed a limit of Mach 2 on all future flights of the advanced X-1 series. .../16

This was only exceeded once, when Everest flew the X-1B to Mach 2.3 to gain high-speed experience ahead of his flights in the Bell X-2. The X-1A was later lost in a pre-launch explosion caused by Bell's use of ulmer leather gaskets in the LOX tank .../17
(img. The X-hunters)

You can read more about the X-1A and the many other rocket research aircraft that flew over Edwards AFB in my forthcoming book, Beyond Blue Skies /END
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