Mach Match

Did an XP-86 beat Yeager to the punch?

The North American XP-86 Sabre, in flight over the Mojave Desert. Was it the first to break the so-called sound barrier? (USAF. NASM photo no. A-38492-C)
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(Bell program manager Dick Frost recalled the first boom laid down on the dry lake in February 1947 as Bell pilot Slick Goodlin did his crack-the-whip maneuver in the X-1 model with the thicker wing, pulling 8.7 Gs at Mach 0.80 and snapping back abruptly, to negative Gs. It was a sharp crack, not the ba-boom that would later become so familiar over the Mojave.

After the first flight of the XP-86, Welch dropped into Horkey’s office at the Inglewood plant in Los Angeles to talk about some “funny” readings on the airspeed indicator. He explained the “stuck” phenomenon he encountered at 350 knots while accelerating downhill, then the sudden jump to 410 knots, then the drop back to 350 knots as he leveled out at 25,000 feet. Horkey asked if the flight recorder showed anything odd. Welch confessed that the dive wasn’t on the flight card. “I was just feeling it out, so I wasn’t running the camera,” he told Horkey. “You know how brassed off the instrumentation guys get when I run out of film for the landing. Anyway, they said there wasn’t anything wrong with the airspeed system. They checked it out after I landed.”

Horkey thought Welch may have run into some Mach effects and told him to take another look next time he was up at altitude. (Down the road, before Mach indicators became standard equipment, the only signal to the pilot that the aircraft was going supersonic was the hangup on the airspeed indicator as the shock wave passed over the indicator’s static source, followed by the hump in the indicated airspeed. This occurred at various airspeeds, depending on the altitude and temperature at which Mach 1 was exceeded.)
“Meanwhile, I’ll see about getting NACA to help us out,” Horkey said. “They have that fancy new radar theodolite at Muroc that can tell us how fast, how high, and where you are within a gnat’s ass. But we have to get on their schedule.”

Welch knew that the new NACA equipment was being used to track Yeager’s lights in the X-1. He also knew that North American didn’t have a prayer of getting on the theodolite until Yeager had done his thing. Welch was on his own.

On October 9, Welch’s wife delivered a baby boy. When she called her mother to announce the birth, she also dropped the news of another blessed event. The new dad had days earlier made aviation history by becoming the first pilot to fly faster than the speed of sound. She made her mother promise not to tell anyone, explaining that it wasn’t just a family confidence, but a military secret.

One week after Welch had pushed the XP-86 over into what he believed was a Mach 1 dive, the X-1 flew at Mach 0.925, faster than the Mach 0.92 achieved on October 10. Yeager was sure he had done it. Ridley had worked his magic on the horizontal stabilizer trim mechanism and Yeager was certain he had popped through. The entire X-1 flight test team was at Pancho’s that Friday evening waiting for the data reduction people to show up with the official figures. Yeager and Pancho were huddled in a corner. The X-1 pilot had a furrowed brow. He was trying to explain to Pancho that he might not have been pointing toward the Fly Inn when he finally pushed through the big barrier. That might explain the absence of a boom earlier in the day, when he was virtually certain he had finally made the first supersonic flight. When Pancho pointed out that Welch had sure made one hell of a boom more than a week ago, Yeager insisted that it was just a fluke. Pancho arched her eyebrows and noted that it had heated up a stable full of fillies at her hacienda.

Then the data sifters showed up, half elated, half despondent. Yeager had gone a lot faster than ever before. He had come as close as you can get and still had not made the ultimate penetration. The most careful analysis showed that on the morning flight, the X-1 had attained Mach 0.997. Another pint of rocket fuel and it would have slid through.

On October 13, Welch called Ferren to check on the status of the Sabre, which Ferren reported would be ready first thing next morning. “By the way, L.A. is insisting that like the last two flights, the next one be made with the gear down, ” he added.

“We can focus on gear-down tests on the next two flights, but I want the option to retract the gear if I need to,” Welch replied, his mind working at warp speed. Why were they doing this? Was the Air Force making sure there would be no more surprise, albeit unofficial, booms?

Early Tuesday morning, October 14, Welch taxied the company Navion onto the ramp of North American’s hangar at Muroc’s North Base. The XP-86 had already been rolled out. Also on the ramp was the P-82 chase plane. Fellow test pilot Bob Chilton would be flying chase again.

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