4 May 1927: Charles A. Lindbergh completes his last series of flight tests of the Ryan NYP, N-X-211, Spirit of St. Louis. Flying at 50 feet (15.2 meters) over San Diego Bay, he times the Spirit‘s flight from marker to marker with a stop watch. The airspeed indicator jumps past 130 miles per hour (209.2 kilometers per hour). He records indicated air speed and engine r.p.m. at various power settings. At 1,500 r.p.m. the Spirit can fly at 96 miles per hour (154.5 kilometers per hour). He makes three runs in each direction to come up with averages.
After the speed runs, Lindbergh flies back to Camp Kearney for load tests. Take-off distances are measured while increasing the fuel load in 50 gallon (189.3 liter) increments.
“Twilight is thickening. We stake the Spirit of St. Louis down and leave it under guard. . . When I get back to the city, I telegraph my partners that the tests are satisfactorily completed. . . .“
—The Spirit of St. Louis, by Charles A. Lindbergh, Charles Scribner’s Sons, 1953, Chapter 37 at Page 128.
Following its first flight from Dutch Flats on 28 April 1927, Charles A. Lindbergh continued flight testing of the new Ryan NYP, N-X-211, Spirit of St. Louis, over the following week from the Camp Kearney parade grounds (now known as Kearney Mesa) near San Diego, California.
Data was gathered for takeoff and landing distances, obstacle clearance, power settings, fuel consumption, rates of climb, air speeds, speeds over a measured distance, instrument calibrations. . . All the things that need to be known so that reliable planning for a transcontinental and transoceanic flight could be carried out.
In his book, The Spirit of St. Louis, (Charles Scribner’s and Sons, 1953) Lindbergh wrote about having a gust of wind blow his clipboard containing the carefully collected data out the Spirit‘s window, and his efforts to recover it, which he did.
This photograph of the legendary airplane flying at Camp Kearney was taken by Donald A. Hall, the engineer who designed it.
26 April 1948: At Muroc Field (now known as Edwards Air Force Base), in the high desert of southern California, North American Aviation test pilot George Welch put the prototype XP-86 Sabre, 45-59597, into a 40° dive and broke the Sound Barrier. It is only the second U.S. aircraft to fly supersonic. The first was the Bell X-1, piloted by Chuck Yeager, only a few months earlier.
Or, maybe not.
In his book, Aces Wild: The Race For Mach 1, fellow North American Aviation test pilot Albert W. Blackburn makes the case that George Welch had taken the prototype XP-86 Sabre supersonic on its first flight, 1 October 1947, and that he had done so three times before Chuck Yeager first broke the Sound Barrier with the Bell X-1 rocketplane, 14 October 1947. Blackburn described two runs through the NACA radar theodolite with speeds of Mach 1.02 and 1.04 on 13 November 1947.
Mr. Blackburn speculates—convincingly, in my opinion—that Secretary of the Air Force W. Stuart Symington, Jr., ordered that Welch’s excursions beyond Mach 1 were to remain secret. However, during a radio interview, British test pilot Wing Commander Roland Prosper (“Bee”) Beamont, C.B.E, D.S.O. and Bar, D.F.C. and Bar, stated that he had flown through the Sound Barrier in the number two XP-86 Sabre prototype (45-59598). Once that news became public, the U.S. Air Force released a statement that George Welch had flown beyond Mach 1 earlier, but gave the date as 26 April 1948.
It wasn’t long after the first flight of the XP-86 on October 1, 1947, that Welch dropped into Horkey’s [Edward J. Horkey, an aerodynamicist at North American Aviation] office at the Inglewood plant. He wanted to talk about his recent flight and some “funny” readings in the airspeed indicator. He had made a straight-out climb to more than 35,000 feet. Then, turning back toward Muroc Dry Lake, he began a full-power, fairly steep descent.
“I started at about 290 knots,” Welch was explaining to Horkey. “In no time I’m at 350. I’m still going down, and I’m still accelerating but the airspeed indicator seems stuck like there’s some kind of obstruction in the pitot tube. I push over a little steeper and by this time I’m through 30,000 feet. All of a sudden, the airspeed indicator flips to 410 knots. The aircraft feels fine, no funny noises, no vibration. Wanted to roll off to the left, but no big deal. Still, I leveled out at about 25,000 and came back on the power. The airspeed flicked back to 390. What do you think?”
“. . . You may be running into some Mach effects. . . .”
— Aces Wild: The Race For Mach 1, by Al Blackburn, Scholarly Resources Inc., Wilmington, Delaware, 1999, at Pages 147–148.
The “funny” reading of the airspeed indicator became known as the “Mach jump.” George Welch was the first to describe it.
The Sabre became a legendary jet fighter during the Korean War. 9,860 were built by North American, as well as by licensees in Canada, Australia and Japan.
George Welch had been recommended for the Medal of Honor for his actions as a P-40 Warhawk fighter pilot in Hawaii, December 7, 1941. He was killed while testing a North American Aviation F-100A Super Sabre, 12 October 1954.
21 March 1962: A black bear named “Yogi” was ejected from a supersonic Convair B-58A Hustler to test the B-58’s escape capsule. Ejected at 35,000 feet (10,668 meters) from a B-58 flying at Mach 1.3 (approximately 870 miles per hour/1,400 kilometers per hour), the bear landed unharmed 7 minutes, 49 seconds later.
Previous testing with human subjects had resulted in fatalities so it was decided to continue with animal subjects while problems were resolved. Black bears (Ursus americanus) were used for these tests because their internal organs are arranged similar to humans.
The rocket booster carried the capsule 225 feet (69 meters meters) above the B-58 before beginning its descent.
Regrettably, although the bears survived the ejection tests, they were killed so that their organs could be examined. This would not be acceptable today.
7 March 1961: Launched over Silver Lake, a dry lake bed near the California/Nevada border, at 10:28:33.0 a.m., Pacific Standard Time, test pilot Major Robert M. White, U.S. Air Force, flew the number two North American Aviation X-15 hypersonic research rocketplane, 56-6671, to Mach 4.43 (2,905 miles per hour/4,675 kilometers per hour) and 77,450 feet (23,607 meters), becoming the first pilot to exceed Mach 4.
This was the first flight for the number two X-15 with the Reaction Motors XLR99-RM-1 engine, which was rated at 57,000 pounds of thrust (253.55 kilonewtons).
The flight plan called for a burn time of 116 seconds, an altitude of 84,000 feet (25,603 meters) and a predicted maximum speed of Mach 4.00. The actual duration of the engine burn was 127.0 seconds. Peak altitude was lower than planned, at 77,450 feet (23,607 meters). The longer burn and lower altitude translated into the higher speed.
The total duration of the flight, from the air drop from the Boeing NB-52B Stratofortress carrier, 52-008, to touchdown at Edwards Air Force Base, was 8 minutes, 34.1 seconds.