Tag Archives: Captive Flight

10 March 1959

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. The chase plane is a Lockheed F-104A-15-LO Starfighter, 56-0768. This Starfighter suffered an engine failure on take off at Edwards AFB, crashed and was destroyed, 30 June 1959. (NASA)

10 March 1959: With North American Aviation’s Chief Engineering Test Pilot Albert Scott Crossfield in its cockpit, the X-15 hypersonic 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 drop 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 B-52 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)

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.

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.)

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 planned 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.

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 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/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)

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.

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.

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 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.

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)

© 2019, Bryan R. Swopes

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18 February 1977

Space Shuttle Enterprise captive flight test, 18 February 197718 February 1977: The prototype space shuttle orbiter Enterprise (OV-101) made its first captive flight aboard NASA 905, the Boeing 747-123 Shuttle Carrier Aircraft. On this flight, no one was aboard Enterprise. NASA 905 was flown by Aircraft Commander Fitzhugh L. Fulton, Jr., Pilot Thomas C. McMurty, and Flight Engineers Louis E. Guidry, Jr. and Victor W. Horton.

This photograph shows the crew of the Shuttle Carrier Aircraft, NASA 905, in 1981: From left, they are, Tom McMurty, pilot; Vic Horton, flight engineer; Fitz Fulton, command pilot; and Ray Young, flight engineer (replacing Guidry). The Space Shuttle Columbia is attached to NASA 905. (NASA)
This photograph shows the crew of the Shuttle Carrier Aircraft, NASA 905, in 1981: From left, they are, Tom McMurty, pilot; Vic Horton, flight engineer; Fitz Fulton, command pilot; and Ray Young, flight engineer (replacing Guidry). The Space Shuttle Columbia is attached to NASA 905. (NASA)

The duration of the first captive flight was 2 hours, 5 minutes. The Enterprise/SCA combination reached a maximum speed of 287 miles per hour (462 kilometers per hour) and altitude of 16,000 feet (4,877 meters).

NASA describes the photograph above:

The Space Shuttle prototype Enterprise rides smoothly atop NASA’s first Shuttle Carrier Aircraft (SCA), NASA 905, during the first of the shuttle program’s Approach and Landing Tests (ALT) at the Dryden Flight Research Center, Edwards, California, in 1977. During the nearly one year-long series of tests, Enterprise was taken aloft on the SCA to study the aerodynamics of the mated vehicles and, in a series of five free flights, tested the glide and landing characteristics of the orbiter prototype.

In this photo, the main engine area on the aft end of Enterprise is covered with a tail cone to reduce aerodynamic drag that affects the horizontal tail of the SCA, on which tip fins have been installed to increase stability when the aircraft carries an orbiter.

Boeing 747-123, N905NA, during wake vortex studies, 20 September 1974. The other aircraft in the photograph are a Cessna T-37B, N807NA and a Learjet 24, N701NA. (NASA)
Boeing 747-123, N905NA, during wake vortex studies, 20 September 1974. The other aircraft in the photograph are a Cessna T-37B, N807NA, and a Learjet 24, N701NA. (NASA)

NASA 905 (the airplane’s call sign is based on its FAA registration, N905NA) was originally built by Boeing for American Airlines as a 747-123 airliner, serial number 20107. It was delivered to American 29 October 1970 with the registration N9668. NASA acquired the airliner 18 July 1974 for use in wake vortex studies.

Modification to the SCA configuration began in 1976. Most of the interior was stripped and the fuselage was strengthened. Mounting struts for the space shuttle were added and end plates for additional stability were attached to the horizontal tail plane. The 747 retained the red, white and blue horizontal stripes of American Airlines’ livery until the early 1980s.

The standard Pratt & Whitney JT95-3A high bypass ratio turbofan engines were upgraded to JT9D-7J turbofans. This increased thrust from 46,950 pounds to 50,000 pounds (222.41 kilonewtons) each. The JT9D-7J is a two-spool, axial-flow turbofan engine with a single stage fan section, 14-stage compressor section and 4-stage turbine. This engine has a maximum diameter of 7 feet, 11.6 inches (2.428 meters), is 12 feet, 10.2 inches (3.917 meters) long and weighs 8,850 pounds (4,014 kilograms).

This image shows NASA 905 as configured for wake vortex studies and as a Shuttle Carrier Aircraft. Artwork courtesy of Tim Bradley Imaging.
This image shows NASA 905 as configured for wake vortex studies and as a Shuttle Carrier Aircraft. Artwork courtesy of Tim Bradley Imaging.

NASA 905 is 231 feet, 10.2 inches (70.668 meters) long with a wingspan of 195 feet, 8 inches (59.639 meters) and overall height of 63 feet, 5 inches (19.329 meters). Its empty weight is 318,053 pounds (144,266 kilograms) and maximum takeoff weight is 710,000 pounds (322,050 kilograms).

While carrying a space shuttle, the SCA maximum speed is 0.6 Mach (443 miles per hour, or 695  kilometers per hour). The service ceiling is 15,000 feet (4,572 meters) and its range is 1,150 miles (1,850.75 kilometers).

NASA 905 is displayed at Independence Park at Space Center Houston, a science and space learning center in Houston, Texas.

35 years, 2 months, 10 days after their first combination flight, the prototype Space Shuttle Orbiter Enterprise (OV-101) and Shuttle Carrier Aircraft NASA 905, touch down together for the last time, at John F. Kennedy International Airport, 11;23 a.m., EST, 27 April 2012. (AP)
35 years, 2 months, 10 days after their first combination flight, the prototype Space Shuttle Orbiter Enterprise (OV-101) and Shuttle Carrier Aircraft NASA 905, touch down together for the last time, at John F. Kennedy International Airport, 11:23 a.m., EST, 27 April 2012. (AP)

© 2017, Bryan R. Swopes

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