Did an XP-86 beat Yeager to the punch?
- By Al Blackburn
- Air & Space magazine, January 1999
USAF. NASM photo no. A-38492-C
(Page 3 of 6)
On Monday evening, September 29, after some XP-86 taxi tests, Welch was at Pancho’s having dinner with Palmer. He was quietly pleased at how well the first outing had gone. He noted that the X-1 crowd looked pretty glum. The little rocketship hadn’t flown in more than two weeks. Palmer reported the rumor that Ridley was working on giving Yeager more pitch control through the trim mechanism. “It looks as though Wednesday is my big chance,” Welch told Palmer. “A supersonic dive is for sure not on the flight card for the first flight, so I’ll have to do it without recording data. It’s agreed that I’ll pull up the landing gear, just to get a feel for how it flies in the clean condition. Without making a record in the usual way, you’ll have to be my data bank. If on Wednesday morning you hear a sharp boom like a clap of thunder, be sure and write it down—what it sounded like, what time, reaction from others, stuff like that.”
The first flight of the XP-86 did indeed take place on Wednesday, October 1. Welch climbed with full power to 10,000 feet above sea level, which was 7,700 feet above the Mojave Desert floor. On his wing was North American engineering test pilot Bob Chilton in a P-82 Twin Mustang. The right cockpit of the dual-fuselage fighter was occupied by a cameraman.
In a little more than 10 minutes, Welch had reach 35,000 feet. Leveling out, he watch the indicated airspeed climb to 320 knots. He estimated that should be Mach 0.90. He had been heading east and was just passing over the El Mirage dry lake. Rolling into a 40-degree dive, he turned to the west. His aircraft was pointing at Pancho’s hacienda, several miles south of Rogers Dry Lake. The airspeed indicator seemed to be stuck at about 350 knots, but the Sabre was behaving just fine. At 29,000 feet there was a little wing roll. Correcting the roll, Welch pushed into a steeper dive. The airspeed indicator suddenly jumped to 410 knots and continued to rise. At 25,000 feet he brought the Sabre back to level flight and reduced power. The wing rocked again and the airspeed jumped from nearly 450 back to 390. Welch pulled up into a barrel roll to the left followed by one to the right, not unlike the victory rolls used in the recent war by returned fighter pilots to let their crews know they had bagged an enemy aircraft.
Before he left for Los Angeles to brief the Sabre project people, Welch called Palmer, who reported that a big ba-boom had nearly bounced her out of bed. She added that Pancho, a big Yeager supporter, had heard it too but attributed it to some mining operation up in the hills.
(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.