Tag Archives: Final Flight

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

9 October 1999

9 October 1999: At a Saturday air show at Edwards Air Force Base, California, NASA Research Pilot Rogers E. Smith and Flight Test Engineer Robert R. Meyer, Jr., flew Lockheed SR-71A-LO 61-7980, NASA 844, on what would be the very last flight of a Blackbird. Although it was scheduled to fly again for the Sunday air show, a serious fuel leak prevented that flight.

61-7980 (Lockheed serial number 2031) was the final SR-71A to be built.

NASA 844 was retired after the final flight and placed in flyable storage, but in 2002, it was placed on static display at the Dryden Flight Research Center,¹ Edwards Air Force Base, California.EC92-02273 

¹ In 2014, DFRC was renamed the NASA Neil A. Armstrong Flight Research Center (AFRC).

© 2017, Bryan R. Swopes

3 October 1967

Major William J. Knight, United States Air Force, with the North American Aviation X-15A-2, 56-6671. (U.S. Air Force)

3 October 1967: The 188th flight of the X-15 Program was the 53rd for the Number 2 aircraft, 56-6671. It had been extensively modified by North American Aviation to an X-15A-2 configuration following a landing accident which had occurred 9 November 1962. The fuselage was lengthened 28 inches (0.711 meters) to accommodate a liquid hydrogen fuel tank for a scramjet engine that would be added to the ventral fin, a new tank for additional hydrogen peroxide to generate steam for the rocket engine turbo pump, and external propellant tanks to allow the rocketplane to reach higher speeds and altitudes. The entire surface of the X-15 was covered with an ablative coating to protect the metal structure from the extreme heat it would encounter on this flight.

Minor issues delayed the takeoff but finally, after they were corrected, and with Pete Knight in the X-15’s cockpit, it was carried aloft under the right wing of Balls 8, a Boeing NB-52B Stratofortress, 52-008.

At 45,000 feet (13,716 meters) over Mud Lake, Nevada, the X-15 was droppeded at 14:31:50.9 local time. Knight fired the Reaction Motors XLR99-RM-1 rocket engine and began to climb and accelerate. After 60 seconds, the ammonia and liquid oxygen propellants in the external tanks was exhausted, so the the tanks were jettisoned to eliminate their weight and aerodynamic drag.

The X-15A-2 climbed to 102,100 feet (31,120 meters) and Pete Knight leveled off, still accelerating. After 140.7 seconds of engine burn, Knight shut the XLR99 down. He noticed that thrust seemed to decrease gradually and the X-15 continued to accelerate to 6,630 feet per second (2,021 meters per second), or Mach 6.72.

North American Aviation X-15A-2 56-6671 is carried to launch altitude under the right wing of the Boeing NB-52B Stratofortress 52-008. (U.S. Air Force)
North American Aviation X-15A-2 56-6671 is carried to launch altitude under the right wing of the Boeing NB-52B Stratofortress 52-008. The scramjet is attached to the ventral fin. (U.S. Air Force)
North American Aviation X-15A-2 56-6671 immediately after being released from the mothership, Boeing NB-52B Stratofortress 52-008, Balls 8, over Mud Lake, Nevada, 3 October 1967. The steam trail is hydrogen peroxide used to power the rocket engine turbopump. (U.S. Air Force)
North American Aviation X-15A-2 56-6671 immediately after being released from the mothership, Boeing NB-52B Stratofortress 52-008, Balls 8, over Mud Lake, Nevada, 3 October 1967. The steam trail is hydrogen peroxide used to power the rocket engine turbopump. (U.S. Air Force) 
The North American Aviation X-15A-2 56-6671 ignites the XLR99 engine after being released from the mothership, Balls 8, 3 October 1967. (U.S. Air Force)
The X-15A-2’s XLR99-RM-1 rocket engine ignites after release from the mothership, Balls 8, 3 October 1967. (U.S. Air Force) 

Shock waves from the dummy scramjet mounted on the ventral fin impinged on the fin’s leading edge and the lower fuselage, raising surface temperatures to 2,700 °F. (1,482 °C.) The Inconel X structure started to melt and burn through.

Pete Knight entered the high key over Rogers Dry Lake at 55,000 feet (16,764 meters) and Mach 2.2, higher and faster than normal. As he circled to line up for Runway One Eight, drag from the scramjet caused the X-15 to descend faster and this set him up for a perfect approach and landing. Because of heat damage, the scramjet broke loose and fell away from the X-15.

Knight touched down after an 8 minute, 17.0 second flight. His 4,520 mile per hour (7,274 kilometers per hour) maximum speed is a record that still stands.

Firefighters cool down the ventral fin of the North American Aviation X-15A-2 56-6671 after its last landing on Rogers Dry Lake, 3 October 1967.(U.S. Air Force)
Firefighters cool down the ventral fin of the North American Aviation X-15A-2 56-6671 after its final landing on Rogers Dry Lake, 3 October 1967.(U.S. Air Force)

The X-15A-2 suffered considerable damage from this hypersonic flight. It was returned to North American for repairs, but before they were completed, the X-15 Program came to an end. This was 56-6671’s last flight. It was sent to the National Museum of the United States Air Force where it is part of the permanent collection.

In a ceremony at the White House, President Lyndon B. Johnson presented the Harmon International Trophy to Major William J. Knight.

The Harmon International Trophy at the Smithsonian Institution National Air and Space Museum. (NASM)
The Harmon International Trophy at the Smithsonian Institution National Air and Space Museum. (NASM)

© 2016, Bryan R. Swopes

27 September 2008

Sikorsky MH-53M Pave Low IV, 68-8284, “Cowboy 26,” prepares for its final combat mission, Iraq, 27 September 2008. (A1C Jason Epley, U.S. Air Force)

27 September 2008: A United States Air Force Sikorsky MH-53M Pave Low IV special operations helicopter, serial number 68-8284, assigned to the 20th Expeditionary Special Operations Squadron, flew its final combat mission before being withdrawn from service and retired after 40 years and 12,066.6 flight hours.

“Cowboy 26” was flown by Major Philip Cooper, Captain Peter Hettinger, and Colonel Scott Howell, with Technical Sergeant Henry Woodie, Staff Sergeant Shawn Lewis, Senior Airman Eric Harp, and Airman 1st Class Joshua Lucas.

68-8284 was built by the Sikorsky Aircraft Corporation at Bloomfield, Connecticut, as one of 40 HH-53C Super Jolly Green Giants for Combat Search and Rescue (CSAR). It was delivered to the Air Force in August 1968. 68-8284 was assigned to the 40th Air Rescue and Recovery Squadron  at Nakhon Phanom Royal Thai Air Force Base, 1971–1972. It operated as “Jolly Green 55.”

On 5 September 1971, with flight crew Major Jerry R. Thompson, Gary L. Gamble (CP),  FE Raymond Duarte and PJs William D. Brinson and Michael D Vogele, it rescued the survivors of “Knife 33,” a 21st SOS CH-3E that went down in Laos. On 19 December 1971 (Capt Harold O. Jones (P), David G. Daus (CP), FE Jerrold T. Dearmans, with PJs Leon Fullwood and William D. Brinson, the crew of Falcon 74, a 13th TFS/432 TFW F-4D Phantom II which had gone down shot down 17 December by a SAM near Ban Poung Ban in northeastern Laos. Maj. William T. Stanley, Capt. Lester O’Brien were safely recovered.

A U.S. Air Force Sikorsky HH-53C Super Jolly Green Giant hovers to hoist a pararescueman with one downed pilot, while a second waits on the ground, 16 June 1967. The blade tip vortices are visible because of the high humidity. (This image has been reoriented and cropped from the original photograph.) (National Archives at College Park)

8284 was later assigned to the 67th Aerospace Rescue and Recovery Squadron (39th Aerospace Rescue and Recovery Wing) at RAF Woodbridge, Suffolk, England. 68-8284 has been constantly modernized and upgraded. It was initially converted to the MH-53J Pave Low III/Enhanced configuration by the Naval Air Rework Facility, NAS Pensacola, Florida, in the late 1980s. The helicopter was further modified to the MH-53M Pave Low IV configuration at the Naval Air Depot, MCAS Cherry Point, North Carolina.

The MH-53M Pave Low IV is designed for operations in darkness. (Staff Sergeant Aaron Allmon, U.S. Air Force) 080927-F-7823A-433

The MH-53M Pave Low IV is a variant of Sikorsky’s S-65 heavy-lift military transport helicopter series.  The MH-53M is a single main rotor, single tail rotor, twin-engine helicopter. It has a crew of six: 2 pilots, 2 flight engineers and 2 gunners. The Pave Low IV is equipped with Terrain-Following Radar and Forward Looking Infrared (FLIR) for low-level operations in darkness and low visibility.

The MH-53M fuselage is 67 feet, 2.4 inches (20.483 meters) long, and the helicopter has a maximum length of 91 feet, 11.34 inches (28.025 meters) with rotors turning and the refueling boom extended. The height to the top of the main rotor pylon is 17 feet, 1.68 inches (5.224 meters). The maximum height (rotors turning) is 24 feet, 10.88 inches (7.592 meters).

Sikorsky HH-53C 3-view illustration with dimensions. (Sikorsky Historical Archives)

The fully-articulated 6-blade main rotor has a diameter of 72 feet, 2.7 inches (22.014 meters). The main rotor turns counter-clockwise at 185 r.p.m. (100% Nr), as seen from above. (The advancing blade is on the helicopter’s right.) The main rotor blades are built with titanium spars and have -16° of twist. The semi-articulated four-blade tail rotor has a diameter of 16 feet, 0 inches (4.877 meters) and is positioned on the left side of the tail pylon. It turns clockwise at 792 r.p.m., as seen from the helicopter’s left side. (The advancing blade is below the axis of rotation.) The gap between rotor arcs is just 4.437 inches (11.270 centimeters).

Empty, the MH-53M weighs 32,000 pounds (14,515 kilograms). Its maximum takeoff weight is 46,000 pounds (20,865 kilograms).

Its two General Electric T64-GE-100 axial-flow turboshaft engines have a Normal Continuous Power rating of 3,810 shaft horsepower at 85 °F. (30 °C.), Military Power rating of 4,090 shaft horsepower, and a Maximum Power rating of 4,330 shaft horsepower. The T64-GE-100 is 79 inches (2.007 meters) long, 20 inches (0.508 meters) in diameter and weighs 720 pounds (327 kilograms). Output (100% N2) is 13,600 r.p.m.

Two Sikorsky HH-53C Super Jolly Green Giants of the 39th Aerospace Rescue and Recovery Wing fly in formation over Goose Bay, Canada, 11 June 1978. 68-8284 is the ship closest to the camera, painted gray. (TSgt. Robert C. Leach/U.S. Air Force)
Two Sikorsky HH-53C Super Jolly Green Giants of the 39th Aerospace Rescue and Recovery Wing fly in formation over Goose Bay, Labrador, Canada, 11 June 1978. 68-8284 is the ship closest to the camera, painted gray. (TSgt. Robert C. Leach/U.S. Air Force)

The MH-53M has a maximum speed of 196 miles per hour (315 kilometers per hour) and a service ceiling of 16,000 feet (4877 meters). It carries two 450-gallon (1,703 liter) jettisonable fuel tanks under each sponson.

The MH-53M is armed with two M134 7.62mm miniguns and a GAU-18/A .50 caliber machine gun.

A Sikorsky MH-53J Pave Low III Enhanced from the 16th Special Operations Wing ready to refuel from a Lockheed MC-130E Combat Talon, 21 October 2001, classified location Operation Enduring Freedom. (TSGT Scott Reed, USAF) U.S. National Archives 6523525

At the time they were retired, the MH-53Ms were the fastest, heaviest, most powerful helicopters in the United States Air Force inventory.

After leaving Iraq, 68-8284 was transported by C-17 Globemaster III to England. It was loaned to the Royal Air Force Museum Cosford, where it is on display.

Sikorsky MH-53M Pave Low IV 68-8284 with another Pave Low IV on their final mission . 27 September 2008. (U.S. Air Force 080927-F-7823A-409)

Recommended: On a Steel Horse I Ride: A History of the MH-53 Pave Low Helicopters in War and Peace, by Darrel D. Whitcomb. Air University Press, Air Force Research Institute, Maxwell Air Force Base, Alabama, September 2012.

© 2019, Bryan R. Swopes

8 September 2001

Special Air Mission 27000, a Boeing VC-137C, 72-7000, on final approach for landing.

8 September 2001: Special Air Mission 27000, a Boeing VC-137C, serial number 72-7000, served as an airborne office and transport for seven United States presidents over 29 years. It made its last flight from Andrews Air Force Base, Maryland to San Bernardino International Airport, California, where technicians from Boeing disassembled the aircraft and transported it in sections to the Ronald Reagan Presidential Library and Museum at Simi Valley, California. It was reassembled and is on display inside the Air Force One Pavilion.

Aboard for its final flight were Secretary of the Air Force James G. Roche, Vice Chief of Staff Lieutenant General Lance W. Lord, U.S. Air Force, and former First Lady of the United States, Nancy Reagan.

The VC-137C was a specially-built Model 707-353B four-engine jet airliner. Known by the call sign Air Force One when the President is aboard, it otherwise is referred to as Special Air Mission 27000. Its sister ship, 72-6000, is at the National Museum of the United States Air Force, where it recently was returned to display after renovation.

Boeing VC-137C 72-7000 on display at the Air Force One Pavilion, Ronald Reagan Presidential Library and Museum, Simi Valley, California. (Wikipedia)

© 2015, Bryan R. Swopes