Tag Archives: 56-6670

4 November 1960

At the left, Boeing NB-52A 52-003 carries X-15 56-6670 while on the right, NB-52B 52-008 carries X-15 56-6671.(NASA)
At the left, Boeing NB-52A 52-003 carries X-15 56-6670 while on the right, NB-52B 52-008 carries X-15 56-6671. (NASA)

4 November 1960: This photo shows one of the four attempts NASA made at launching two X-15 aircraft in one day. This attempt occurred November 4, 1960.

None of the four attempts was successful, although one of the two aircraft involved in each attempt usually made a research flight.

In this case, Air Force test pilot Major Robert A. Rushworth flew X-15 , 56-6670, on its sixteenth flight to a speed of Mach 1.95 and an altitude of 48,900 feet (14,905 meters).

© 2016, Bryan R. Swopes

24 October 1968

William Harvey Dana, NASA Research Pilot. (National Aeronautics and Space Administration E-5327)

24 October 1968: William Harvey Dana takes the first North America Aviation X-15 hypersonic research rocketplane, 56-6670, for the 199th and final flight of the X-15 program.

Carried aloft by NASA’s Boeing NB-52A Stratofortress mothership, 52-003, the first X-15A was launched over Smith Ranch Dry Lake, about half-way between the city of Reno and the NASA High Range Tracking Station at Ely, Nevada, at 10:02:47.3 a.m., Pacific Daylight Time (17:02:47.3 UTC). Bill Dana started the Reaction Motors XLR99-RM-1 rocket engine for a planned 84 second burn. The flight plan called for the X-15 to reach Mach 5.45 and 250,000 feet (76,200 meters).

The rocketplane’s performance was very close to plan, a tribute to Dana’s piloting skill. The engine burned out after 83.8 seconds. The maximum speed was slightly lower than planned at Mach 5.38, while the peak altitude was a little higher, at 255,000 feet (77,724 meters).

Dana glided back to Edwards Air Force Base. The total duration of the flight was 11 minutes, 28.3 seconds.

Dana made his first flight in the North American Aviation X-15 hypersonic research rocketplane on 4 November 1965. He reached a maximum speed of Mach 4.22, and a peak altitude of 80,200 feet (24,445 meters). He made a total of sixteen flights in the X-15s. Dana’s highest speed was Mach 5.38, and his highest altitude, 306,900 feet, (93,543 meters), on 1 November 1966.

This had been 56-6670’s 81st flight, and the 141st time it had been carried aloft aboard a B-52.

A. Scott Crossfield, wearing a David Clark Co. XMC-2 full-pressure suit, which he helped to design and test, with the first of three North American X-15s, 56-6670. (North American Aviation, Inc.)

56-6670 is the first of three X-15s built by North American Aviation’s Los Angeles Division for NASA, the United States Air Force, and the United States Navy, to investigate the effects of hypersonic flight (Mach 5+). On 8 June 1959, North American Aviation Chief Engineering Test Pilot, and former NACA research test pilot, Albert Scott Crossfield, had made the first glide flight of 56-6670, also launched by 52-003.

NASA Research Pilot William H. Dana with North American X-15A 56-6672 on Rogers Dry Lake. (NASA)

From 8 June 1959 to 24 October 1968, the three X-15s were flown by twelve test pilots, three of whom would qualify as astronauts in the X-15. Two would go on to the Apollo Program, and one, Neil Alden Armstrong, would be the first human to set foot on the surface of the Moon, 20 July 1969. Joe Engle would fly the space shuttle. Four of the test pilots, Petersen, White, Rushworth, and Knight, flew in combat during the Vietnam War, with Bob White being awarded the Air Force Cross. Petersen, Rushworth and White reached flag rank.

Overhead view of X-15A-1 56-6670 shows the rocketplane’s overall fineness ratio and short wings. (North American Aviation, Inc.)

Flown by a single pilot/astronaut, the X-15 is a mid-wing monoplane with dorsal and ventral fin/rudders and stabilators. The wing had no dihedral, while the stabilators had a pronounced 15° anhedral. The short wings have an area of 200 square feet (18.58 square meters) and a maximum thickness of just 5%. The leading edges are swept to 25.64°. There are two small flaps but no ailerons. The entire vertical fin pivots for yaw control.

Above 100,000 feet (30,840 meters) altitude, conventional aircraft flight control surfaces are ineffective. The X-15 is equipped with a system of reaction control jets for pitch, roll and yaw control. Hydrogen peroxide was passed through a catalyst to produce steam, which supplied the control thrusters.

The forward landing gear consists of a retractable oleo strut with steerable dual wheels and there are two strut/skids at the rear of the fuselage. The gear is retracted after the X-15 is mounted on the NB-52 and is extended for landing by its own weight.

The rocketplane’s cockpit featured both a conventional control stick as well as side-controllers. It was pressurized with nitrogen gas to prevent fires. The pilot wore an MC-2 full-pressure suit manufactured by the David Clark Company of Worcester, Massachusetts, with an MA-3 helmet. The suit was pressurized below the neck seal with nitrogen, while the helmet was supplied with 100% oxygen. This pressure suit was later changed to the Air Force-standardized A/P22S.

North American Aviation, Inc. X-15A 56-6670 on Rogers Dry Lake, Edwards Air Force Base, California. (NASA)

The X-15 is 50.75 feet (15.469 meters) long with a wing span of 22.36 feet (6.815 meters). The height—the distance between the tips of the dorsal and ventral fins—is 13.5 feet (4.115 meters). The stabilator span is 18.08 feet (5.511 meters). The fuselage is 4.67 feet (1.423 meters) deep and has a maximum width of 7.33 feet (2.234 meters).

The X-15s were built primarily of a nickel/chromium/iron alloy named Inconel X, along with corrosion-resistant steel, titanium and aluminum. Inconel X is both very hard and also able to maintain its strength at the very high temperatures the X-15s were subjected to by aerodynamic heating. It was extremely difficult to machine and special fabrication techniques had to be developed.

X-15 56-6670 with NB-52A 52-003, 13 April 1960. (NASA)

Since the X-15 was built of steel rather than light-weight aluminum, as are most aircraft, it is a heavy machine, weighing approximately 14,600 pounds (6,623 kilograms) empty and 34,000 pounds (15,422 kilograms) when loaded with a pilot and propellants. The X-15s carried as much as 1,300 pounds (590 kilograms) of research instrumentation, and the equipment varied from flight to flight. The minimum flight weight (for high-speed missions): was 31,292 pounds (14,194 kilograms) The maximum weight was 52,117 pounds (23,640 kilograms) at drop (modified X-15A-2 with external propellant tanks).

Initial flights were flown with a 5 foot, 11 inch (1.803 meters)-long air data boom at the nose, but this would later be replaced by the “ball nose” air sensor system. The data boom contained a standard pitot-static system along with angle-of-attack and sideslip vanes. The boom and ball nose were interchangeable.

Delays in the production of the planned Reaction Motors XLR99 rocket engine forced engineers to adapt two vertically-stacked Reaction Motors XLR11-RM-5 four-chamber rocket engines to the X-15 for early flights. This was a well-known engine which was used on the previous rocketplanes. The XLR11 burned a mixture of ethyl alcohol and water with liquid oxygen. Each of the engines’ four chambers could be ignited individually. Each engine was rated at 11,800 pounds of thrust (58.49 kilonewtons) at Sea Level.

Thiokol Reaction Motors Division XLR99-RM-1 rocket engine. (U.S. Air Force)

The Reaction Motors XLR99-RM-1 rocket engine was throttleable by the pilot from 28,500 to 60,000 pounds of thrust. The engine was rated at 50,000 pounds of thrust (222.41 kilonewtons) at Sea Level; 57,000 pounds (253.55 kilonewtons) at 45,000 feet (13,716 meters), the typical drop altitude; and 57,850 pounds (257.33 kilonewtons) of thrust at 100,000 feet (30,480 meters). Individual engines varied slightly. A few produced as much as 61,000 pounds of thrust (271.34 kilonewtons).

The XLR99 burned anhydrous ammonia and liquid oxygen. The flame temperature was approximately 5,000 °F. (2,760 °C.) The engine was cooled with circulating liquid oxygen. To protect the exhaust nozzle, it was flame-sprayed with ceramic coating of zirconium dioxide. The engine is 6 feet, 10 inches (2.083 meters) long and 3 feet, 3.3 inches (0.998 meters) in diameter. It weighs 910 pounds (413 kilograms). The Time Between Overhauls (TBO) is 1 hour of operation, or 100 starts.

The XLR99 proved to be very reliable. 169 X-15 flights were made using the XLR99. 165 of these had successful engine operation. It started on the first attempt 159 times.

The highest speed achieved during the program was with the modified number two ship, X-15A-2 56-6671, flown by Pete Knight to Mach 6.70 (6,620 feet per second/4,520 miles per hour/ kilometers per hour) at 102,700 feet (31,303 meters). On this flight, the rocketplane exceeded its maximum design speed of 6,600 feet per second (2,012 meters per second).

The maximum altitude was reached by Joe Walker, 22 August 1963, when he flew 56-6672 to 354,200 feet (107,960 meters).

The longest flight was flown by Neil Armstrong, 20 April 1962, with a duration of 12 minutes, 28.7 seconds.

The North American Aviation, Inc., X-15A-1, 56-6670, being brought into the Arts and Industries building, June 1969. (Smithsonian Institution Archives SI-A-4145-23-A)

North American Aviation X-15A-1 56-6670 is on display at the Smithsonian Institution National Air and Space Museum. X-15A-2 56-6671 is at the National Museum of the United States Air Force.

North American Aviation Inc./U.S. Air Force/NASA X-15A 56-6670, hypersonic research rocketplane on display at the National Air and Space Museum. (NASM)

© 2023, Bryan R. Swopes

Albert Scott Crossfield, Jr. (2 October 1921–19 April 2006)

Albert Scott Crossfield, aeronautical engineer and test pilot, 1921–2006. (Jet Pilot Overseas)
Albert Scott Crossfield, Jr., Aeronautical Engineer and Test Pilot, 1921–2006. (Jet Pilot Overseas)

Albert Scott Crossfield, Jr., was born at Berkeley, California, 2 October 1921, the second of three children of Albert Scott Crossfield and Lucia Dwyer Scott Crossfield. (“Scott Crossfield” is the family name, going back for many generations.) His father was a chemist who was the superintendent of the Union Oil Refinery in Wilmington, California. At the age of 5 years, the younger Scott Crossfield contracted pneumonia. He was comatose for a time and not expected to survive. When he finally began to recover, he was confined to bed for many months. The effects of this illness lasted throughout his childhood.

It was during this time that he developed his interest in aviation. He learned to draw, studied airplanes, and built scale models. Charles F. (“Carl”) Lienesch, who was a pilot for the Union Oil Company, gave Scotty his first ride aboard an airplane at age 6. As a teenager, he took flight lessons in an Inland Sportster at the Wilmington Airport.

Inland R400 Sportster NC267N, circa 1939. (William T. Larkins)

After his family bought a farm in Oregon, Scott Crossfield continued flight lessons and soloed a Curtis Robin at the age of 15. He earned his private pilot certificate at 18. After graduating from high school, “Scotty” helped his father with the family farm before attending the University of Washington as a student of aeronautical engineering. He took a job at Boeing to pay his tuition and support.

Ensign A. S. Crossfield, Jr.

After America’s entry into World War II, Scott Crossfield enlisted in the U.S. Army Air Corps as an aviation cadet, but because of expected delays in training, quickly transferred to the U.S. Navy. He enlisted as a Seaman 2/c in the Navy’s V-5 Program at the Naval Reserve Aviation Base, Seattle, Washington, on 21 February 1942. He began Primary Flight Training there, 7 May 1942. Scotty completed military flight training and was commissioned an Ensign, United States Navy, in December 1942.

On 21 April 1943, Ensign Albert Scott Crossfield, U.S. Navy, married Miss Alice Virginia Knoph at Corpus Christi, Texas.

Promoted to lieutenant (junior grade) with date of precedence 21 March 1944.

During World War II, Scott Crossfield served as a fighter pilot, flight and gunnery instructor, flying the Chance Vought F4U Corsair and Grumman F6F Hellcat. Though he was assigned to Fighting Squadron FIFTY-ONE (VF-51) aboard the Independence-class light aircraft carrier USS Langley (CVL-27), he did not serve in combat. He was promoted to the rank of lieutenant 1 August 1945. Scotty was released from active duty 31 December 1945. After the war he joined a Naval Reserve squadron and flew the Goodyear Aircraft Co. FG-1D Corsair at NAS Sand Point, Washington.

A Goodyear FG-1D Corsair, Bu. No. 92150, unfolding its wings at NAS Sand Point, circa late 1940s. The orange band around the fuselage shows that this airplane is assigned to a Naval Reserve squadron. (U.S. Navy)

During this time he resumed his education at the University of Washington and graduated with a bachelor’s degree in aeronautical engineering in 1949, and a master’s degree in 1950. As a graduate student he was the operator of the university’s Kirsten Aeronautical Laboratory wind tunnel.

The NACA High Speed Flight Station, 24 August 1954. The Boeing P2B-1S Superfortress is parked at the northeast corner of the ramp. (NASA)

In 1950 Scott Crossfield joined the National Advisory Committee for Aeronautics (NACA, the predecessor of NASA) as an Aeronautical Research Pilot at the NACA High Speed Flight Station, Edwards Air Force Base, California. He flew many high-performance jet aircraft like the North American Aviation F-100 Super Sabre, and experimental airplanes such as the Convair XF-92, Douglas X-3, Bell X-4 and X-5. He also flew the research rocket planes, making 10 rocket flights in the Bell X-1 and 77 in the Douglas D-558-II Skyrocket.

Douglas D-558-2 Bu. No. 37974 dropped from Boeing P2B-S1 Superfortress 84029, 1 January 1956. (NASA)
Douglas D-558-2 Skyrocket, Bu. No. 37974, is dropped from Boeing P2B-S1 Superfortress, Bu. No. 84029, 1 January 1956. (NASA)

On 20 November 1953, Scott Crossfield became the first pilot to fly faster than twice the speed of sound (Mach 2). The D-558-II was carried aloft by a Boeing P2B-1S Superfortress drop ship (a four-engine B-29 long range heavy bomber which had been transferred from the U.S. Air Force to the Navy, then heavily modified by Douglas) to 32,000 feet (9,754 meters) and then released. Scotty fired the LR8 rocket engine and climbed to 72,000 feet (21,945 meters). He put the Skyrocket into a shallow dive and, still accelerating, passed Mach 2 at 62,000 feet (18,898 meters). After the rocket engine’s fuel was expended, he flew the rocketplane to a glide landing on Rogers Dry Lake.

In 1955 Crossfield left NACA and joined North American Aviation, Inc., as Chief Engineering Test Pilot. He planned and participated in the design and operation of the X-15 hypersonic research rocketplane for the Air Force and NASA. He also worked closely with the David Clark Co., in the development of the project’s full-pressure suits.

Scott Crossfield testing an experimental David Clark Co. XMC-2 full-pressure suit in a thermal chamber at Wright Field. (Ralph Morse, LIFE Magazine/National Archives College Park Collection)

Milton O. Thompson, another X-15 test pilot, wrote in At the Edge of Space,

“. . . he was intimately involved in the design of the aircraft and contributed immensely to the success of the design, as a result of his extensive rocket airplane experience. . . Scott was responsible for a number of other excellent operational and safety features built into the aircraft. Thus, one might give Scott credit for much of the success of the flight program. . . .”

At the Edge of Space, by Milton O. Thompson, Smithsonian Institution Press, Washington and New York, 1992, at Page 3

Scott Crossfield, NAA Chief Engineering Test Pilot; Edmond Ross Cokeley, NAA Director of Flight Test;  and Charles H. Feltz, NAA Chief Engineer, with an X-15 hypersonic research rocketplane. (North American Aviation via Jet Pilot Overseas)

In 1959–1960, Scott Crossfield flew all of the contractor’s demonstration phase flights for the X-15, including 16 captive carry flights under the wing of the NB-52A Stratofortress while systems were tested and evaluated, one glide flight, and thirteen powered flights. He reached a a maximum altitude of 88,116 feet (26,858 meters) on Flight 6, and a maximum speed of Mach 2.97 (1,960 miles per hour/3,154 kilometers per hour) on Flight 26. The X-15 was then turned over to NASA and the Air Force. The X-15 Program involved a total of 199 flights from 1959 until 1968.

A. Scott Crossfield, wearing a David Clark Co. XMC-2 full-pressure suit, which he helped to design and test, with the first of three North American X-15s, 56-6670. (North American Aviation, Inc.)

After leaving the X-15 Program, Scott Crossfield continued as a Systems Director with North American Aviation, Inc., working on the Apollo Command and Service Module and the S-IVB second stage of the Saturn V rocket. He left North American in the late ’60s and served as an executive with Eastern Air Lines and Hawker Siddeley. He also continued as a aeronautical engineering consultant to private industry and government.

Among many other awards, Scott Crossfield was received the Harmon Trophy, the Collier Trophy, and the Iven C. Kincheloe Award of the Society of Experimental Test Pilots..

Scott Crossfield's 1962 Cessna 210A Centurion, photographed at Santa Monica Airport, California, 26 September 1999. (AirNikon Collection, Pima Air & Space Museum, Tucson, Arizona via airliners.net)
Scott Crossfield’s Cessna 210A Centurion, N6579X, photographed at Santa Monica Airport, California, 26 September 1999. (AirNikon Collection, Pima Air & Space Museum, Tucson, Arizona via airliners.net, used with permission)

In 1980 Crossfield resumed flying when he purchased a 1960 Cessna 210A Centurion, N6579X, serial number 21057579. This was a single-engine, four-place light airplane, powered by an air-cooled Continental six-cylinder engine. He had flown more than 2,000 hours in this airplane when it crashed during a severe thunderstorm, 19 April 2006, while on a flight from Prattville, Alabama, to Manassas, Virginia.

Albert Scott Crossfield, Jr., was killed. His remains are interred at the Arlington National Cemetery, Arlington, Virginia.

Albert Scott Crossfield, Jr., Test Pilot. (LIFE Magazine via Jet Pilot Overseas)

Highly recommended: Always Another Dawn: The Story Of A Rocket Test Pilot, by Albert Scott Crossfield and Clay Blair, Jr., The World Publishing Company, Cleveland and New York, 1960.

© 2018, Bryan R. Swopes

17 September 1959

X-15 56-6670 is carried under the right wing of NB-52A 52-003. Scott Crossfield is in the cockpit of the rocket plane. (NASA)

17 September 1959: After previously making one glide flight, North American Aviation Chief Engineering Test Pilot Albert Scott Crossfield made the first powered flight of an X-15 hypersonic research rocket plane.

Carried aloft under the right wing of an eight-engine Boeing NB-52A Stratofortress bomber, USAF serial number 52-003, the first of three North American Aviation X-15s, 56-6670, was airdropped from 35,000 feet (10,668 meters) over Rosamond Dry Lake, west of Edwards Air Force Base. Launch time was 08:08:48.0 a.m., Pacific Daylight Savings Time (15:08.48.0 UTC).

Scott Crossfiled prepares for a flight in the North American Aviation X-15A
Scott Crossfield prepares for a flight in the North American Aviation X-15A. Crossfield is wearing a conformal (face seal) helmet with his David Clark Co. MC-2 full-pressure suit. (NASA/North American Aviation, Inc.)

The X-15 was designed to use the Reaction Motors XLR-99 rocket engine, but early in the test program that engine was not yet available so two smaller XLR-11 engines were used. This was engine the same type used in the earlier Bell X-1 rocket plane that first broke the sound barrier in 1948. Though producing just one-fourth the thrust of the XLR-99, it allowed the functional testing of the X-15 to proceed.

The X-15’s two Reaction Motors XLR11 engines. (NASA)

Scott Crossfield wrote:

Two minutes after launch I reached 50,000 feet and pushed over in level flight. Then I dropped the nose slightly for a speed run, meanwhile maneuvering the ship through a series of turns and rolls, conscious of a deep rumbling noise of the rocket and a great rush of wind on the fuselage. It was obvious the black bird was in her element at supersonic speeds. She responded beautifully. I stared in fascination at the Mach meter which climbed from 1.5 Mach to 1.8 Mach and then effortlessly to my top speed for this flight of 2.3 Mach or about 1,500 miles and hour. Then, because I was under orders not to take the X-15 wide open, I shut off three of the rocket barrels. As I slowed down, I recalled the agony at Edwards many years before when we had worked for months pushing, calculating, polishing and who knows what else to achieve Mach 2 in the Skyrocket. Now with the X-15 we had reached that speed in three minutes on our first powered flight and I had to throttle back.

Always Another Dawn, The Story Of A Rocket Test Pilot, by A. Scott Crossfield with Clay Blair, Jr., The World Publishing Company, Cleveland and New York, 1960. Chapter 39 at Pages 362.

X-15A 56-6670 drops from the wing of the B-52 mothership. 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)

The X-15 dropped 2,000 feet (610 meters) while Scott Crossfield ignited the two XLR-11 engines and then started “going uphill.” During the 224.3 seconds burn duration, the X-15 reached Mach 2.11 (1,393 miles per hour/2,242 kilometers per hour) and climbed to 52,300 feet (15,941 meters), both slightly higher than planned.

Problems developed when the rocket engine’s turbo pump case failed, and fire broke out in the hydrogen peroxide compartment, engine compartment and in the ventral fin. Crossfield safely landed on Rogers Dry Lake at Edwards Air Force Base. The duration of the flight was 9 minutes, 11.1 seconds. Damage to the rocket plane was extensive but was quickly repaired. 56-6670 flew again 17 October 1959.

Chief Engineering Test Pilot A. Scott Crossfield climbs out of the cockpt of a North American Aviation X-15A hypersonic research rocketplane. (Der Spiegel)

Over the next nine years the three X-15s would make 199 flights, setting speed and altitude records nearly every time they flew, and expanding NASA’s understanding of flight in the hypersonic range. The first two X-15s, 56-6670 and 56-6671, survived the program. 670 is at the Smithsonian Institution National Air and Space museum and 671 is at the National Museum of the United States Air Force.

Test pilot Albert Scott Crossfield with X-15 56-6670 attached to the right wing pylon of NB-52A 52-003 at Edwards Air force Base. (North American Aviation Inc.)
Test pilot Albert Scott Crossfield with X-15 56-6670 attached to the right wing pylon of NB-52A 52-003 at Edwards Air force Base. (North American Aviation Inc.)

© 2018, Bryan R. Swopes

12 August 1960

Major Robert M. White, U.S. Air Force. (NASA)

12 August 1960: At Edwards Air Force Base, California, Major Robert M. White flew the North American Aviation X-15 rocketplane to an altitude of 136,500 feet (41,605 meters), exceeding the previous unofficial record of 126,200 feet (38,466 meters) set by the late Captain Iven C. Kincheloe, Jr., with the Bell X-2, 7 September 1956.

Iven Kincheloe had been assigned as the Air Force’s project pilot for the X-15. When he was killed on a routine flight, Bob White was designated to replace him.

This was White’s fourth flight in an X-15, and the 19th flight of the X-15 Program. The Number 1 rocketplane, serial number 56-6670, was carried aloft under the right wing of the “mothership,” Boeing NB-52A Stratofortress 52-003. At 08:48:43.0 a.m., PDT, 56-6670 was dropped over Silver Lake, near the Nevada-California border. White fired the two Reaction Motors XLR11-RM-13 rocket engines and they burned for 256.2 seconds.

This flight took place in Phase II of the Program and was intended to gradually increase the envelope of X-15 performance with the XLR11 engines while waiting for the much more powerful XLR99. The purpose of Flight 19 was to reach maximum altitude in order to test the rocketplane’s stability and controllability above the atmosphere.

The X-15 accelerated to Mach 2.52, 1,773 miles per hour (2,853 kilometers per hour) while climbing at nearly a 70° angle and reached a peak altitude of 136,500 feet (41,605 meters). After engine shutdown, White glided to a landing on Rogers Dry Lake and touched down. The duration of the flight was 11 minutes, 39.1 seconds.

Neither Kincheloe’s or White’s altitudes are recognized as records by the Fédération Aéronautique Internationale(FAI). Over the next few years, the X-15 would reach to nearly three times higher.

An X-15 is dropped from the NB-52A, 52-003, at an altitude of 45,000 feet at 0.8 Mach. (NASA)

© 2016, Bryan R. Swopes