Tag Archives: NASA

24 March 1960

Joseph Albert Walker in the cockpit of North American Aviation X-15A 56-6670, after a flight, 1960. (NASA)
Joseph Albert Walker in the cockpit of North American Aviation X-15A 56-6670, after a flight, 1960. (NASA)

24 March 1960: After North American Aviation’s Chief Engineering Test Pilot, Albert Scott Crossfield, had made the first flights in the new X-15 hypersonic research rocketplane (one gliding, eight powered), NASA Chief Test Pilot Joseph Albert Walker made his first familiarization flight.

The X-15, 56-6670, the first of three built by North American Aviation, Inc., was carried aloft under the right wing of a Boeing NB-52A Stratofortress, 52-003, flown by John E. Allavie and Fitzhugh L. Fulton.

The rocketplane was dropped from the mothership over Rosamond Dry Lake at 15:43:23.0 local time, and Joe Walker ignited the Reaction Motors XLR-11 rocket engine. The engine burned for 272.0 seconds, accelerating Walker and the X-15 to Mach 2.0 (1,320 miles per hour/2,124.3 kilometers per hour) and a peak altitude of 48,630 feet (14,822.4 meters). Walker landed on Rogers Dry Lake at Edwards Air Force Base after a flight of 9 minutes, 8.0 seconds.

Joe Walker made 25 flights in the three X-15 rocket planes from 24 March 1960 to 22 August 1963. He achieved a maximum Mach number of 5.92, maximum speed of 4,104 miles per hour (6,605 kilometers per hour) and maximum altitude of 354,200 feet (107,960 meters).

Joe Walker was killed in a mid-air collision between his Lockheed F-104N Starfighter and a North American Aviation XB-70A Valkyrie near Barstow, California, 1 June 1966.

The number one ship, 56-6670, made 81 of the 199 flights of the X-15 Program. It was the first to fly, and also the last, 24 October 1968. Today, it is in the collection of the Smithsonian Institution National Air and Space Museum.

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

© 2017, Bryan R. Swopes

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23 March 1965

Gemini III lifts off at Launch Complex 19, Kennedy Space Center, Cape Canaveral, Florida, 14:24:00 UTC, 23 March 1965. (NASA)
Gemini III lifts off at Launch Complex 19, Cape Kennedy Air Force Station, Cape Canaveral, Florida, 14:24:00 UTC, 23 March 1965. (NASA)

23 March 1965: At 14:24:00 UTC, Gemini III was launched aboard a Titan II GLV  rocket from Launch Complex 19 at the Cape Kennedy Air Force Station, Cape Canaveral, Florida. Major Virgil I. (“Gus”) Grissom, United States Air Force, a Project Mercury veteran, was the Spacecraft Commander, and Lieutenant Commander John W. Young, United States Navy, was the pilot.

The purpose of the mission was to test spacecraft orbital maneuvering capabilities that would be necessary in later flights of the Gemini and Apollo programs. Gemini III made three orbits of the Earth, and splashed down after 4 hours, 52 minutes, 31 seconds. Miscalculations of the Gemini capsule’s aerodynamics caused the spacecraft to miss the intended splash down point by 50 miles (80 kilometers). Gemini III splashed down in the Atlantic Ocean, north east of the Turks and Caicos Islands. The recovery ship was USS Intrepid (CV-11).

Gus Grissom would later command the flight crew of Apollo 1. He was killed with his crew during the tragic fire  during a pre-launch test, 27 January 1967.

John Young served as Spacecraft Commander for Gemini 10, Command Module Pilot on Apollo 10, back-up commander for Apollo 13, commander Apollo 16, and back-up commander for Apollo 17. Later, he was commander of the maiden flight of the space shuttle Columbia STS-1 and again for STS-9 and was in line to command STS-61J.

The flight crew of Gemini III, John W. Young and Virgil I. Grissom. (NASA)
The flight crew of Gemini III, Lieutenant Commander John W. Young, U.S. Navy, and Major Virgil I. Grissom, U.S. Air Force. (NASA)

The two-man Gemini spacecraft was built by the McDonnell Aircraft Corporation of St. Louis, the same company that built the earlier Mercury space capsule. The spacecraft consisted of a reentry module and an adapter section. It had an overall length of 19 feet (5.791 meters) and a diameter of 10 feet (3.048 meters) at the base of the adapter section. The reentry module was 11 feet (3.353 meters) long with a diameter of 7.5 feet (2.347 meters). The weight of the Gemini varied from ship to ship but was approximately 7,000 pounds (3,175 kilograms)

The Titan II GLV was a “man-rated” variant of the Martin SM-68B intercontinental ballistic missile. It was assembled at Martin’s Middle River, Maryland plant so as not to interfere with the production of the ICBM at Denver, Colorado. Twelve GLVs were ordered by the Air Force for the Gemini Program.

The Titan II GLV was a two-stage, liquid-fueled rocket. The first stage was 63 feet (19.202 meters) long with a diameter of 10 feet (3.048 meters). The second stage was 27 feet (8.230 meters) long, with the same diameter. The 1st stage was powered by an Aerojet Engineering Corporation LR-87-7 engine which combined two combustion chambers and exhaust nozzles with a single turbopump unit. The engine was fueled by a hypergolic combination of hydrazine and nitrogen tetroxide. Ignition occurred spontaneously as the two components were combined in the combustion chambers. The LR-87-7 produced 430,000 pounds of thrust. It was not throttled and could not be shut down and restarted. The 2nd stage used an Aerojet LR-91 engine which produced 100,000 pounds of thrust.

The Gemini/Titan II GLV combination had a total height of 109 feet (33.223 meters) and weighed approximately 340,000 pounds (154,220 kilograms) when fueled.

The Gemini III spacecraft is displayed at the Grissom Memorial Museum, Spring Mill State Park, Mitchell, Indiana.

© 2016, Bryan R. Swopes

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23 March 1912–16 June 1977

Wernher von Braun, Director, Marshall Space Flight Center (NASA)
Dr. Wernher von Braun, Director, Marshall Space Flight Center, 1 May 1964. (NASA)

23 March 1912: Wernher Magnus Maximilian Freiherr von Braun, rocket engineer, was born at Wyrzysk, Province of Posen, in the German Empire, in what is now Poland. He was the second of three children of Magnus Alexander Maximillian von Braun, head of the Posen provincial government, and Emmy von Quistorp.

Wernher von Braun originally wanted to be a musician and composer, having learned to play the cello and piano at an early age. After reading a speculative book on space flight, though, his interests shifted.

In 1929, the 17-year-old von Braun joined Verein für Raumshiffahrt, the German rocketry association. He worked with Hermann Oberth in testing liquid-fueled rockets, based on successful rockets designed by Dr. Robert H. Goddard in the United States.

Rudolf Nebel (left) and Wernher von Braun with small liquid-fueled rockets, circa 1930. (Unattributed)
Rudolf Nebel (left) and Wernher von Braun with small liquid-fueled rockets, circa 1930. (Unattributed)

Von Braun graduated from Technische Hochschule Berlin in 1932, with a degree in mechanical engineering (Diplom-Ingenieur). Two years later, he received a doctorate in physics (Dr. phil.) at Friederich-Wilhelm University of Berlin. He also studied at ETH Zürich.

In Germany before World War II, Dr.-Ing. von Braun worked on the problems of liquid-fueled rockets and developed the Aggregat series of rockets, including the A4, which would become known as the V-2 (Vegeltungswaffe 2) military rocket. The German Army’s Ordnance Department gave von Braun a grant to further study liquid-fueled rockets, which he pursued at an artillery range at Kummersdorf, just south of Berlin. As rocketry work expanded, the tests were eventually moved to the Peenemünde Military Test Site on the island of Usedom on the Baltic coast, where von Braun was technical director under Colonel Dr. Ing. Walter R. Dornberger.

Wernher von Braun with a number of German officers at Peenemunde, March 1941. (Left to right) Oberst Dr. Walter Dornberger, General Friederich Olbricht, Major Heinz Brandt, von Braun; others not identified. (Bundesarchiv, Bild 146-1978-Anh.024-03/CC-BY-SA 3.0)
Prof. Dr.-Ing. Wernher von Braun with a number of German officers at Peenemünde, March 1941. (Left to right) Colonel Dr. Ing. Walter Dornberger (partially out of frame), General der Infanterie Friederich Olbricht*, Major Heinz Brandt, Prof. Dr. von Braun; others not identified. (Bundesarchiv, Bild 146-1978-Anh.024-03/CC-BY-SA 3.0) [*General Olbricht developed Operation Valkyrie, the plot to assassinate Hitler and overthrow the Nazi regime.]
Aggregat 4 prototype (probably V-3) ready for launch at Prüfstand VII, August 1942. (Bundesarchiv)

The first successful launch of the A4 took place 3 October 1942. By the end of World War II, Nazi Germany had launched more than 3,200 V-2 rockets against Belgium, England, France and The Netherlands.

As World War II in Europe came to a close and the collapse of Nazi Germany was imminent, von Braun had to choose between being captured by the Soviet Red Army or by the Allies. He surrendered to the 324th Infantry Regiment, 44th Infantry Division, United States Army in the Bavarian Alps, 2 May 1945.

Dornberger, Herber Axter, von Braun and Hans Lindenberg, 3 May 1945. (U.S. Army)
Major-General Dr. Ing. Walter R. Dornberger; Lieutenant-Colonel Herbert Axster, Dornberger’s chief of staff; Prof. Dr.-Ing. Wernher von Braun (with left arm in cast); and Hans Lindenberg, chief propulsion engineer; at Reutte, Austria, 3 May 1945. (Technician 5th Class Louis Weintraub, U.S. Army)

Under Operation Paperclip, Wernher von Braun and many other scientists, engineers and technicians were brought to the United States to work with the U.S. Army’s ballistic missile program at Fort Bliss, Texas, White Sands Proving Grounds, New Mexico, and the Redstone Arsenal, Huntsville, Alabama.

Sufficient parts and materiel and been transferred from Germany to construct more than one hundred V-2 rockets for testing at White Sands. Over a five year period, there were 67 successful launches, but it is considered that as much knowledge was gained from failures as successes.

Dr. von Braun with V-2 rocket compnents in Texas, circa 1945. (Unattributed)
Dr. von Braun with V-2 rocket components at White Sands Proving Grounds, New Mexico, 1 November 1946. (Thomas D. McAvoy)

In 1950, von Braun and his team were sent to Redstone Arsenal, Huntsville, Alabama, where they worked on more advanced rockets. The first production rocket was the short-range ballistic missile, the SSM-A-14 Redstone, which was later designated PGM-11. This rocket was capable of carrying a 3.8 megaton W39 warhead approximately 200 miles (322 kilometers) The first Redstone was launched at Cape Canaveral Air Force Station, 20 August 1953. Modified Redstone MRLV rockets were used to launch the first Mercury spacecraft with NASA astronauts Alan Shepherd and Gus Grissom. Von Braun later worked on the U.S. Army’s Jupiter-A intermediate range ballistic missile. A modified Jupiter-C was used to launch Explorer 1, the United States’ first satellite.

Explorer 1 launch, Launch Complex 26A, Cape Canaveral Air Force Station, 1 February 1958, 03:48:00 UTC. (NASA)
Mercury-Redstone 4 (Liberty Bell 7) launch at Pad 5, Cape Canaveral Air Force Station, 12 20 36 UTC, 21 July 1961. (NASA)

Wernher von Braun travelled to Germany in 1947 to marry his cousin, Maria Luise von Quistorp, and then returned to the United States. He became a naturalized citizen of the United States of America in 1955.

The von Braun family, circa 1955 (U.S. Army)
Prof. Dr. von Braun with his family, circa 1957. Left to right, Maria Luise von Braun, Margrit Cécile von Braun, Dr. von Braun and Iris Careen von Braun. (U.S. Army)

In 1960 von Braun and hist team were transferred from the Army Ballistic Missile Agency to NASA’s new Marshall Space Flight Center at Redstone Arsenal. He was now able to pursue his original interest, manned flight into space. Work proceeded on the Saturn rocket series, which were intended to lift heavy payloads into Earth orbit. This resulted in the Saturn A, Saturn B and the Saturn C series, ultimately becoming the Saturn V moon rocket.

With the Apollo Program coming to an end, Dr. von Braun left NASA in 1972. A year later, he was diagnosed with kidney cancer. Wernher von Braun died of pancreatic cancer, 17 June 1977 at the age of 65 years.

Apollo 4 Saturn V (AS-501) on the launch pad at sunset, the evening before launch, 8 November 1967. (NASA)

© 2017, Bryan R. Swopes

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16 March 1966, 17:41:02 UTC, T minus Zero

Gemini VIII lifts off from Launch Complex 19, Kennedy Space Center, 17:41:02 UTC, 16 March 1966. (NASA)
Gemini VIII lifts off from Launch Complex 19, Cape Kennedy Air Force Station, 17:41:02 UTC, 16 March 1966. (NASA)

16 March 1966: At 17:41:02 UTC (12:41:02 p.m. Eastern Standard Time) Gemini VIII, with astronauts Neil A. Armstrong and David R. Scott, lifted off from Launch Complex 19 at the Cape Kennedy Air Force Station, Cape Kennedy, Florida, aboard a Titan II GLV booster. Their mission was to rendezvous and dock with an Agena Target Vehicle launched earlier aboard an Atlas rocket.

David R. Scott and Neil A. Armstrong, flight crew of Gemini VIII. (NASA)
David R. Scott and Neil A. Armstrong, flight crew of Gemini VIII. (NASA)

The docking, the first ever of two vehicles in Earth orbit, was successful, however after about 30 minutes the combined vehicles begin rolling uncontrollably. The Gemini capsule separated from the Agena, and for a few minutes all seemed normal. But the rolling started again, reaching as high as 60 r.p.m.

The astronauts were in grave danger. Armstrong succeeded in stopping the roll but the Gemini’s attitude control fuel was dangerously low. The cause was determined to be a stuck thruster, probably resulting from an electrical short circuit.

The mission was aborted and the capsule returned to Earth after 10 hours, 41 minutes, landing in the Pacific Ocean. U.S. Air  Force pararescue jumper (“PJs”) parachuted from a C-54 and attached a flotation collar to the Gemini capsule. The astronauts were recovered by the Gearing-class destroyer USS Leonard F. Mason (DD-852).

The Gemini VIII spacecraft is displayed at the Neil Armstrong Air and Space Museum, Wapakoneta, Ohio.

Gemini VIII with flotation collar. (NASA)

The two-man Gemini spacecraft was built by the McDonnell Aircraft Corporation of St. Louis, the same company that built the earlier Mercury space capsule. The spacecraft consisted of a reentry module and an adapter section. It had an overall length of 19 feet (5.791 meters) and a diameter of 10 feet (3.048 meters) at the base of the adapter section. The reentry module was 11 feet (3.353 meters) long with a diameter of 7.5 feet (2.347 meters). The weight of the Gemini varied from ship to ship but was approximately 7,000 pounds (3,175 kilograms)

The Titan II GLV was a “man-rated” variant of the Martin SM-68B intercontinental ballistic missile. It was assembled at Martin’s Middle River, Maryland plant so as not to interfere with the production of the ICBM at Denver, Colorado. Twelve GLVs were ordered by the Air Force for the Gemini Program.

The Titan II GLV was a two-stage, liquid-fueled rocket. The first stage was 63 feet (19.202 meters) long with a diameter of 10 feet (3.048 meters). The second stage was 27 feet (8.230 meters) long, with the same diameter. The 1st stage was powered by an Aerojet Engineering Corporation LR-87-7 engine which combined two combustion chambers and exhaust nozzles with a single turbopump unit. The engine was fueled by a hypergolic combination of hydrazine and nitrogen tetroxide. Ignition occurred spontaneously as the two components were combined in the combustion chambers. The LR-87-7 produced 430,000 pounds of thrust. It was not throttled and could not be shut down and restarted. The 2nd stage used an Aerojet LR-91 engine which produced 100,000 pounds of thrust.

The Gemini/Titan II GLV combination had a total height of 109 feet (33.223 meters) and weighed approximately 340,000 pounds (154,220 kilograms) when fueled.

The Atlas-Agena Target vehicle takes off at Launch Complex 14, 17:00:00 UTC, 16 March 1966. (NASA)
The Atlas-Agena Target Vehicle takes off at Launch Complex 14, Cape Kennedy Air Force Station, 15:00:03 UTC, 16 March 1966. (NASA)

The docking, the first ever of two vehicles in Earth orbit, is successful, however after about 30 minutes the combined vehicles begin rolling uncontrollably. The Gemini capsule separates and for a few minutes all seems normal. But the rolling starts again, reaching as high as 60 r.p.m. The astronauts are in grave danger. Armstrong succeeds in stopping the roll but the Gemini’s attitude control fuel is dangerously low. The cause is determined to be a stuck thruster. The mission is aborted and the capsule returns to Earth after 10 hours, 41 minutes, landing in the Pacific Ocean.

Agena Target Vehicle as seen from Gemini VIII. (NASA)
Agena Target Vehicle as seen from Gemini VIII. (NASA)

© 2017, Bryan R. Swopes

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10 March 1959

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.)

10 March 1959: With North American Aviation’s Chief Engineering Test Pilot Albert Scott Crossfield in its cockpit, the X-15 high speed research rocket plane was airborne for the first time. X-15A 56-6670 was carried aloft under the wing of the Boeing NB-52A Stratofortress mother ship, 52-003, for a series of captive flights. The purpose was to verify that all the systems on both the X-15 and the mothership were properly functioning up to the point that the drop would occur.

The NB-52A Stratofortress flight crew, left to right: Harry W. ("Bill") Berkowitz, NAA, Launch Panel Operator; Captain John E. ("Jack") Allavie, USAF, Pilot; Captain Charles C. Bock, Jr., USAF, Aircraft Commander, at Edwards AFB, 7 February 1959. (U.S. Air Force)
The NB-52A Stratofortress flight crew, left to right: Harry W. (“Bill”) Berkowitz, NAA, Launch Panel Operator; Captain John E. (“Jack”) Allavie, USAF, Pilot; Captain Charles C. Bock, Jr., USAF, Aircraft Commander, at Edwards AFB, 7 February 1959. (U.S. Air Force via Jet Pilot Overseas)
North American Aviation X-15A 56-6670 carried aloft by Boeing NB-52A Stratofortress 52-003. The absence of frost on the fuselage of the X-15 shows that no cryogenic propellants are aboard for this captive flight. (NASA)
North American Aviation X-15A 56-6670 carried aloft by Boeing NB-52A Stratofortress 52-003. The absence of frost on the fuselage of the X-15 shows that no cryogenic propellants are aboard for this captive flight. (NASA)

Fully settled in my tiny flight office, I could speak by radio to the B-52 pilot, Charlie Bock, who was about thirty feet away in the nose of the mother plane, out of sight. . . .

As we sat, waiting at the end of the long runway while chase planes took off and circled, the clock on the instrument panel of the X-15 showed 0955. . . On signal, B-52 pilot Charlie Bock cobbed the eight engines, standing hard on the brake pedal. As the engines wound up to full military power, the X-15 trembled and the noise was tremendous. Through my radio earphones I heard Bock call a countdown for the benefit of the official movie cameramen who would record  every inch of the takeoff:

“Five . . . four . . . three . . . two . . . one. BRAKE RELEASE.”

One hundred thirty tons of aluminum, fuel, Inconel X, five men and the hope of a nation began rolling down the long runway. . .

As we rolled, the huge runway distance markers flashed by, clocking our path: 14,000 . . . 13,000 . . . 12,000 . . . 8,000. When the X-15 air-speed indicator reached 170 knots, I noted only a minor vibration. We would continue the takeoff. 6,000 . . . 5,000 . . . 4,000, and we broke ground. It was smooth and gentle, like the take-off of an airliner. The air-speed indicator crept up to 260 knots. The parched brown desert fell away. . . .

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, Chapters 34 and 35 at Pages 316–321.

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 gross weight of the combined aircraft was 258,000 pounds (117,000 kilograms). After a takeoff roll of 6,200 feet (1,890 meters) the B-52/X-15 lifted of at 168 knots (193 miles per hour/311 kilometers per hour). During the 1 hour, 8 minute flight the the B-52 climbed to 45,000 feet (13,716 meters) and reached a speed of 0.83 Mach (548 miles per hour/881 kilometers per hour).

The X-15A rocketplane was designed and built for the U.S. Air Force and the National Advisory Committee for Aeronautics (NACA, the predecessor of NASA) by North American Aviation, Inc., to investigate the effects of hypersonic flight (Mach 5+). Design work started in 1955 and a mock-up had been completed after just 12 months. The three X-15s were built at North American’s Los Angeles Division, at the southeast corner of Los Angeles International Airport (LAX), on the shoreline of southern California.

Scott Crossfield discusses the X-15 with North American Aviation engineers Edmond R. Cokeley, Director of Flight Test, and Charles H. Feltz, Chief Engineer for the X-15 Program. (North American Aviation, Inc.)

The first flight took place 8 June 1959, again, with Scott Crossfield in the cockpit of the Number 1 ship, 56-6670.

While earlier rocketplanes, the Bell X-1 series, the the Douglas D-558-II, and the Bell X-2, were airplanes powered by rocket engines, the X-15 was a quantum leap in technology. It was a spacecraft.

Like the other rocketplanes, the X-15 was designed to be carried aloft by a “mothership,” rather than to takeoff and climb to the test altitude under its own power. The carrier aircraft was originally to be a Convair B-36 intercontinental bomber but this was soon changed to a Boeing B-52 Stratofortress. Two B-52s were modified to carry the X-15: NB-52A 52-003, The High and Mighty One, and NB-52B 52-008, Balls 8.

A North American Aviation F-100 Super Sabre chase plane follows NB-52A 52-003 prior to launch of an X-15. (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.

One pilot, John B. (“Jack”) McKay, was seriously injured during an emergency landing at Mud Lake, Nevada, 9 November 1962. Michael James Adams, was killed when the Number 3 ship, 56-6672, went into a hypersonic spin and broke up on the program’s 191st flight, 15 November 1967.

Scott Crossfield prepares for a flight in the North American Aviation X-15A. Crossfield is wearing a David Clark Co. MC-2 full-pressure suit and MA-3 helmet, which he helped to develop. (NASA)

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 dihdral, 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/rudder 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.

X-15A cockpit with original Lear Siegler instrument panel. (NASA)

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.

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).

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

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.

Two Reaction Motors Division XLR11-RM-5 four-chamber rocket engines installed on an X-15. (NASA)

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 XLR-11 burned a mixture of ethyl alcohol and water with liquid oxygen. Each of the engines’ chambers could be ignited individually. Each engine was rated at 11,800 pounds of thrust (58.49 kilonewtons) at Sea Level.

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.

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

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.

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)

© 2017, Bryan R. Swopes

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