Tag Archives: Flight Test

8 June 1959, 16:38:40 GMT

Albert Scott Crossfield (1921–2006) (AP)

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 B-52 Stratofortress, NB-52A-1-BO 52-003, at 37,550 feet (11,445 meters) over Rosamond Dry Lake at 08:38:40 a.m, Pacific 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.

North American Aviation Chief Engineering Test Pilot Albert Scott Crossfield in the cockpit of X-15A 56-670 before a flight. (NASA)
North American Aviation Chief Engineering Test Pilot Albert Scott Crossfield in the cockpit of an X-15 before a flight. (LIFE Magazine via Jet Pilot Overseas)

In his autobiography, Scott Crossfield described the first flight:

“Three” . . . “Two” . . . “One” . . .

“DROP”

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.”

X-15A 56-6670 under the wing of NB-52A 52-003 at high altitude. Scott Crossfield is in the cockpit of the rocketplane. Air Force Flight Test Center History Office, U.S. Air Force)
X-15A 56-6670 under the wing of NB-52A 52-003 at high altitude. Scott Crossfield is in the cockpit of the rocketplane. (Air Force Flight Test Center History Office, U.S. Air Force)

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. . . .

X-15A 56-6670 drops from the wing of the B-52 mothership. This is a glide flight as there is no frost from cryogenic propellants showing of the fuselage. The vapor trail is from hydrogen peroxide that powers the aircraft power systems. Note the roll to the right as the X-15 drops from the pylon. (NASA)
X-15A 56-6670 drops from the wing of the B-52 mothership, 8 June 1959. The vapor trail is from venting hydrogen peroxide used to power the aircraft pumps and generators. Note the roll to the right as the X-15 drops away from the Stratofortress. (NASA)

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.

This photograph shows the second North American Aviation X-15A, 56-6671, flaring to land on Rogers Dry Lake, Edwards Air Force Base, California The rear skids are just touching down. The white patches on the aircraft's belly is frost from residual cryogenic propellants remaining in its tanks. (U.S. Air Force)
This photograph shows the second North American Aviation X-15A, 56-6671, flaring to land on Rogers Dry Lake, Edwards Air Force Base, California. The rear skids are just touching down. The white patches on the aircraft’s belly are frost from residual cryogenic propellants remaining in its tanks after a powered flight. (U.S. Air Force)

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 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. It is in the collection of National Air and Space Museum at Washington, D.C.

Scott Crossfield in a David Clark Co. XMC-2 full-pressure suit with an MA-3 conformal helmet, and the first North American Aviation X-15A, 56-6670. (Scott Crossfield Foundation)

© 2015, Bryan R. Swopes

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4 May 1927

Spirit of St. Louis over San Diego, May 1927. (San Diego Air and Space Museum)

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.

© 2016, Bryan R. Swopes

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1 May 1927

Spirit of St. Louis at Kearney Mesa, San Diego, California. (Donald A. Hall)

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.

© 2015, Bryan R. Swopes

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26 April 1948

est Pilot George Welch flying the prototype North American Aviation XP-86 Sabre, 45-59597. (U.S. Air Force)
Test Pilot George Welch flying the prototype North American Aviation XP-86 Sabre, 45-59597. (U.S. Air Force)

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 CBE, DSO and Bar, DFC 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 Air Force released a statement that George Welch had flown beyond Mach 1 earlier, but gave the date as 26 April 1948.

Test pilot George S. Welch, wearing his distinctive orange helmet, in the cockpit of the prototype XP-86. This photograph was taken 14 October 1947. (U.S. Air Force)
Test pilot George S. Welch, wearing his distinctive orange helmet, in the cockpit of the prototype XP-86. This photograph was taken 14 October 1947. (U.S. Air Force)

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 an F-100A Super Sabre, 12 October 1954.

Test pilot George S. Welch with a North American Aviation F-86 Sabre. (San Diego Air and Space Museum Archives)
Test pilot George S. Welch with a North American Aviation F-86 Sabre. (San Diego Air and Space Museum Archives)

© 2016, Bryan R. Swopes

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21 March 1962

Yogi, an American black bear used as a test subject.
Yogi, an American black bear used as a test subject.

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.

An escape capsule is launched from teh Defensive Systems Officer position of a Convair B-58 Hustler. (U.S. air Force)
An escape capsule is launched from the Defensive Systems Officer position of a Convair B-58 Hustler. (U.S. Air Force)

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.

© 2016, Bryan R. Swopes

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