17 July 1965: At Air Force Plant 42, Palmdale, California, the second North American Aviation B-70 Valkyrie prototype, XB-70A-2-NA 62-0207, took off on its maiden flight enroute Edwards Air Force Base where it would continue the flight test program with its sister ship.
The Valkyrie was designed as a Mach 3+ strategic bomber, capable of flight above 70,000 feet (21,336 meters), with intercontinental range. It’s altitude allowed it to avoid interceptors of the time, but improvements in radar-guided surface-to-air missiles increased its vulnerability. Ultimately, though, political decisions ended the B-70 program.
62-0207 was flown just 46 times, for a total of 92 hours, 22 minutes of flight. Changes to the aircraft corrected the deficiencies discovered in testing the Number 1 XB-70A, 62,-201. The most visible change was 5° dihedral added to the wings for improved stability. On 16 April 1966, 62-0207 reached its maximum design speed, Mach 3.08, which it sustained for 20 minutes.
Less than one year after its first flight, 8 June 1966, the Valkyrie was involved in a mid-air collision with a Lockheed F-104N and crashed just north of Barstow, California. North American’s B-70 test pilot, Al White, was seriously injured and co-pilot, Major Carl Cross, USAF, was killed. NASA test pilot Joe Walker, flying the F-104, was also killed.
8 June 1959: At Edwards Air Force Base, California, North American Aviation’s Chief Engineering Test Pilot, A. Scott Crossfield, made the first flight of the X-15A hypersonic research rocketplane.
56-6670 was the first of three X-15s built for the U.S. Air Force and NASA. It was airdropped from a Boeing NB-52A Stratofortress, 52-003, at 37,550 feet (11,445 meters) over Rosamond Dry Lake at 08:38:40 a.m, Pacific Daylight Time.
This was an unpowered glide flight to check the flying characteristics and aircraft systems, so there were no propellants or oxidizers aboard, other than hydrogen peroxide which powered the pumps and generators.
The aircraft reached 0.79 Mach (522 miles per hour, 840 kilometers per hour) during the 4 minute, 56.6 second flight.
In his autobiography, Scott Crossfield described the first flight:
“Three” . . . “Two” . . . “One” . . .
Inside the streamlined pylon, a hydraulic ram disengaged the three heavy shackles from the upper fuselage of the X-15. They were so arranged that all released simultaneously, and if one failed they all failed. The impact of the release was clearly audible in the X-15 cockpit. I heard a loud “kerchunk.”
The X-15 hung in its familiar place beneath the pylon for a split second. Then the nose dipped sharply down and to the right more rapidly than I had anticipated. The B-52, so long my constant companion, was gone. The X-15 and I were alone in the air and flying 500 miles an hour. In less than five minutes I would be on the ground. . . .
There was much to do in the first hundred seconds of flight. First I had to get the “feel” of the airplane, to make certain it was trimmed out for landing just as any pilot trims an airplane after take-off or . . . when dwindling fuel shifts the center of gravity. Then I had to pull the nose up, with and without flaps, to feel out the stall characteristics, so that I would know how she might behave at touchdown speeds . . . My altimeter unwound dizzily: from 24,000 to 13,000 feet in less than forty seconds. . . .
The desert was coming up fast. At 600 feet altitude I flared out. . . .
In the next second without warning the nose of the X-15 pitched up sharply. It was a maneuver that had not been predicted by the computers, an uncharted area which the X-15 was designed to explore. I was frankly caught off guard. Quickly I applied corrective elevator control.
The nose went down sharply. But instead of leveling out, it tucked down. I applied reverse control. The nose came up but much too far. Now the nose was rising and falling like a skiff in a heavy sea. Although I was putting in maximum control I could not subdue the motions. The X-15 was porpoising wildly, sinking toward the desert at 200 miles an hour. I would have to land at the bottom of an oscillation, timed perfectly; otherwise, I knew, I would break the bird. I lowered the flaps and the gear. . . .
. . . With the next dip I had one last chance and flared again to ease the descent. At that moment the rear skids caught on the desert floor and the nose slammed over, cushioned by the nose wheel. The X-15 skidded 5,000 feet across the lake, throwing up an enormous rooster tail of dust. . . .
—Always Another Dawn: The Story of a Rocket Test Pilot, by A. Scott Crossfield and Clay Blair, Jr., The World Publishing Company, Cleveland and New York, 1960, Chapter 37 at Pages 338–342.
Before the drop, it was discovered that the aircraft’s Stability Augmentation System was inoperative in pitch mode. During the flight it was found that the hydraulic-assisted flight control system was responding too slowly to Crossfield’s inputs. Engineers analyzed the problem and increased the hydraulic system pressure. The problem never recurred.
Scott Crossfield was the world’s most experienced rocketplane pilot with 82 rocketplane flights before the X-15 program. “. . . he was intimately involved in the design of the aircraft and contributed immensely to the success of the design.”
—At The Edge Of Space, by Milton O. Thompson, Smithsonian Institution Press, 1992, Introduction, at Page 3.
North American Aviation X-15A 56-6670 made the first glide flight and the first and last powered flights of the X-15 Program. It made a total of 82 of the 199 X-15 flights. 56-6670 is in the collection of National Air and Space Museum at Washington, D.C.
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.