Tag Archives: North American Aviation Inc.

North American Aviation, Inc., X-15A Hypersonic Research Rocketplane

Rollout AFFTC History Office
North American Aviation, Inc., X-15A-1, 56-6670, at Los Angeles Division, October 1958. (Air Force Flight Test Center History Office)

20 December 1968: After 199 flights, the National Aeronautics and Space Administration cancelled the X-15 Hypersonic Research Program. A 200th X-15 flight had been scheduled, but after several delays, the decision was made to end the program. (The last actual flight attempt was 12 December 1968, but snow at several of the dry lakes used as emergency landing areas resulted in the flight being cancelled.)

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.

The first flight took place 8 June 1959 with former NACA test pilot Albert Scott Crossfield in the cockpit of the Number 1 ship, 56-6670.

Scott Crossfield prepares for a flight in the North American Aviation X-15A.

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.

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. Another, 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.

North American Aviation, Inc. X-15A 56-6670 on Rogers Dry Lake, Edwards Air Force Base, California. (NASA)
North American Aviation, Inc., X-15A-1 56-6670 on Rogers Dry Lake, Edwards Air Force Base, California. (NASA Image E-5251)

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.

 North American Aviation X-15A 56-6672 touches down on Rogers Dry Lake. (NASA)
North American Aviation, Inc., X-15A-3 56-6672 just before touch down on Rogers Dry Lake. (NASA Image E-7469)

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.

X-15A cockpit with original Lear Siegler instrument panel. (NASA)
X-15 cockpit with original Lear Siegler instrument panel. (NASA image E63-9834)

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).

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.

Neil Armstrong with the first North American Aviation X-15A, 56-6670, on Rogers Dry Lake after a flight, 1960. His hand is resting on the rocketplane's ball nose sensor. (NASA)
NASA Research Test Pilot Neil A. Armstrong with the first North American Aviation X-15A, 56-6670, on Rogers Dry Lake after a flight, 1960. His right hand is resting on the rocketplane’s ball nose sensor. (NASA Image E60-6286)

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.

Delays in the production of the planned Reaction Motors XLR99 rocket engine forced engineers to adapt two vertically-stacked Reaction Motors XLR11-RM-13 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’ chambers could be ignited individually. Each engine was rated at 11,800 pounds of thrust (58.49 kilonewtons) at Sea Level.

Two Reaction Motors Division XLR11-RM-5 four-chamber rocket engines installed on an X-15. (NASA)
Two Reaction Motors Division XLR11-RM-13 four-chamber rocket engines installed on an X-15. The speed brakes of the ventral fin are shown in the open position. (NASA)

The Reaction Motors XLR99-RM-1 rocket engine was throttleable by the pilot from 28,500 to 60,000 pounds of thrust (126.77–266.89 kilonewtons). 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 XLR-RM-1 rocket engine. (U.S. Air Force)
Thiokol Corporation 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/7,264 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.

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

Recommended reading:

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

At The Edge Of Space, by Milton O. Thompson, Smithsonian Institution Press, 1992

X-15 Diary: The Story of America’s First Spaceship, by Richard Tregaskis, E.F. Dutton & Company,  New York, 1961; University of Nebraska Press, 2004

X-15: Exploring the Frontiers of Flight, by David R. Jenkins, National Aeronautics and Space Administration http://www.nasa.gov/pdf/470842main_X_15_Frontier_of_Flight.pdf

The X-15 Rocket Plane: Flying the First Wings into Space, by Michelle Evans, University of Nebraska Press, Lincoln and London, 2013

Screen Shot 2016-06-07 at 21.18.14
North American Aviation, Inc., X-15A-2 56-6671 accelerates after igniting its Reaction Motors XLR99-RM-1 rocket engine (NASA)

© 2018, Bryan R. Swopes

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10 December 1947

Jackie Cochran with her P-51B Mustang, NX28388. (FAI)
Jackie Cochran with her P-51B Mustang, NX28388. (FAI)

10 December 1947: Near the Santa Rosa Summit in the Coachella Valley of southeastern California, Jackie Cochran flew her green North American Aviation P-51B Mustang, NX28388, over a 100-kilometer (62 miles) closed circuit, averaging 755.668 kilometers per hour (469.549 miles per hour). She set both a U.S. National and a Fédération Aéronautique Internationale (FAI) World Record.¹

This record still stands.

Jackie Cochran's green North American Aviation P-51B-15-NA Mustang, NX28388. (FAI)
Jackie Cochran’s green North American Aviation P-51B-15-NA Mustang, NX28388. (FAI)
National Aeronautic Association Certificate of Record in the San Diego Air and Space Museum Archive. (Bryan R. Swopes)
National Aeronautic Association Certificate of Record in the San Diego Air & Space Museum Archive. (Bryan R. Swopes)

Screen Shot 2015-01-02 at 09.58.53

NX28388 was the first of three P-51 Mustangs owned by Jackie Cochran. It was a North American Aviation P-51B-15-NA Mustang built at Inglewood, California in 1944. It was assigned NAA internal number 104-25789 and U.S. Army Air Corps serial number 43-24760.

Cochran bought it from North American Aviation, Inc., 6 August 1946. The airplane was registered to Jacqueline Cochran Cosmetics, Inc., 142 Miller Street, Newark, New Jersey, but was based at Jackie’s C-O Ranch at Indio, California. The Mustang was painted “Lucky Strike Green” and carried the number 13 on each side of the fuselage, on the upper surface of the left wing and lower surface of the right wing.

NX28388 was powered by Packard V-1650-7 Merlin V-12, serial number V332415.

Jackie Cochran flew NX28388 in the 1946 Bendix Trophy Race and finished second to Paul Mantz in his P-51C Mustang, Blaze of Noon. Cochran asked Bruce Gimbel to fly the Mustang for her in the 1947 Bendix. There was trouble with the propeller governor and he finished in fourth place. In May 1948, Jackie set two more speed records with NX28388. Jackie and her green Mustang finished in third place in the 1948 Bendix race. She asked another pilot, Lockheed test pilot Sampson Held, to ferry the fighter back to California from Cleveland, Ohio after the race, but,

“. . . my plane crashed, carrying my associate, Sam Held, with it to his death.”The Stars At Noon, by Jacqueline Cochran, Little, Brown and Company, Boston, 1954, Chapter IV at Page 79.

NX28388 had crashed six miles south of Sayre, Oklahoma, 8 September 1948, killing Sam Held. Two witnesses saw a wing come off of the Mustang, followed by an explosion.

Jackie Cochran's North American Aviation P-51B Mustang, NX28388. (San Diego Air and Space Museum Archives)
Jackie Cochran’s North American Aviation P-51B Mustang, NX28388, on the flight line at the Cleveland National Air Races, 1948. The airplane behind the Mustang is Tex Johnston’s Bell P-39Q, “Cobra II.” (San Diego Air and Space Museum Archives)

The P-51B was the first production Mustang to be built with the famous Rolls-Royce Merlin engine, and was virtually identical to the P-51C variant. (The P-51Bs were built by North American Aviation, Inc., at Inglewood, California. P-51Cs were built at North American’s Dallas, Texas plant.) They were 32 feet, 2.97 inches (9.829 meters) long, with a wingspan of 37 feet, 0.31-inch (11.282 meters) and overall height of 13 feet, 8 inches (4.167 meters) high. The fighter had an empty weight of 6,985 pounds (3,168 kilograms) and a maximum gross weight of 11,800 pounds (5,352 kilograms).

P-51Bs and Cs were powered by a liquid-cooled, supercharged, 1,649-cubic-inch-displacement (27.04-liter) Packard V-1650-3 or -7 Merlin single overhead cam (SOHC) 60° V-12 engine which produced 1,380 horsepower at Sea Level, turning 3,000 r.p.m and 60 inches of manifold pressure (V-1650-3) or 1,490 horsepower at Sea Level, turning at 3,000 r.p.m. with 61 inches of manifold pressure (V-1650-7). These were license-built versions of the Rolls-Royce Merlin 63 and 66. The engine drove a four-bladed Hamilton-Standard Hydromatic constant speed propeller with a diameter of 11 feet, 2 inches (3.404 meters).

The P-51B/C had a cruise speed of 362 miles per hour (583 kilometers per hour) and the maximum speed was 439 miles per hour (707 kilometers per hour) at 25,000 feet (7,620 meters). The service ceiling was 41,900 feet (12,771 meters). With internal fuel, the combat range was 755 miles (1,215 kilometers).

In military service, armament consisted of four Browning AN/M2 .50-caliber machine guns, mounted two in each wing, with 350 rounds per gun for the inboard guns and 280 rounds per gun for the outboard.

1,988 P-51B Mustangs were built at North American’s Inglewood, California plant and another 1,750 P-51Cs were produced at Dallas, Texas. This was nearly 23% of the total P-51 production.

Jackie Cochran and her P-51B Mustang, NX28388. (Unattribued)
Jackie Cochran and her P-51B Mustang, NX28388. (Unattributed)

¹ FAI Record File Number 4478

© 2018, Bryan R. Swopes

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7 December 1972 05:33:00 UTC, T + 00:00:00.63

Apollo 17 (AS-512) on the pad at Launch Complex 39A, 21 November 1972. (NASA)
Apollo 17 (AS-512) on the pad at Launch Complex 39A, 21 November 1972. (NASA)

7 December 1972: At 05:33:00.63 UTC (12:33 a.m., Eastern Standard Time), Apollo 17, the last manned mission to The Moon in the 20th century, lifted off from Launch Complex 39A at the Kennedy Space Center, Cape Canaveral, Florida. The destination was the Taurus-Littrow Valley.

The Mission Commander, on his third space flight, was Eugene A. Cernan. The Command Module Pilot was Ronald A. Evans, on his first space flight, and the Lunar Module Pilot was Harrison H. Schmitt, also on his first space flight.

Gene Cernan, seated, with Harrison Schmitt and Ronald Evans. (NASA)
Gene Cernan, seated, with Harrison Schmitt and Ronald Evans. (NASA)

Schmitt was placed in the crew because he was a professional geologist. He replaced Joe Engle, an experienced test pilot who had made sixteen flights in the X-15 hypersonic research rocketplane. Three of those flights were higher than the 50-mile altitude, qualifying Engle for U.S. Air Force astronaut wings.

The launch of Apollo 17 was delayed for 2 hours, 40 minutes, due to a minor mechanical malfunction. When it did liftoff, the launch was witnessed by more than 500,000 people.

Apollo 17/Saturn V (AS-512) at Pad 39A during countdown. (NASA 72C-5901)

The Saturn V rocket was a three-stage, liquid-fueled heavy launch vehicle. Fully assembled with the Apollo Command and Service Module, it stood 363 feet (110.642 meters) tall. The first and second stages were 33 feet (10.058 meters) in diameter. Fully loaded and fueled the rocket weighed 6,200,000 pounds (2,948,350 kilograms). It could lift a payload of 260,000 pounds (117,934 kilograms) to Low Earth Orbit.

The first stage was designated S-IC. It was designed to lift the entire rocket to an altitude of 220,000 feet (67,056 meters) and accelerate to a speed of more than 5,100 miles per hour (8,280 kilometers per hour). The S-IC stage was built by Boeing at the Michoud Assembly Facility, New Orleans, Louisiana. It was 138 feet (42.062 meters) tall and had an empty weight of 290,000 pounds (131,542 kilograms). Fully fueled with 203,400 gallons (770,000 liters) of RP-1 and 318,065 gallons (1,204,000 liters) of liquid oxygen, the stage weighed 5,100,000 pounds (2,131,322 kilograms). It was propelled by five Rocketdyne F-1 engines, producing 1,522,000 pounds of thrust (6770.19 kilonewtons), each, for a total of 7,610,000 pounds of thrust at Sea Level (33,850.97 kilonewtons). These engines were ignited seven seconds prior to lift off and the outer four burned for 168 seconds. The center engine was shut down after 142 seconds to reduce the rate of acceleration. The F-1 engines were built by the Rocketdyne Division of North American Aviation at Canoga Park, California.

The S-II second stage was built by North American Aviation at Seal Beach, California. It was 81 feet, 7 inches (24.87 meters) tall and had the same diameter as the first stage. The second stage weighed 80,000 pounds (36,000 kilograms) empty and 1,060,000 pounds loaded. The propellant for the S-II was liquid hydrogen and liquid oxygen. The stage was powered by five Rocketdyne J-2 engines, also built at Canoga Park. Each engine produced 232,250 pounds of thrust (1,022.01 kilonewtons), and combined, 1,161,250 pounds of thrust (717.28 kilonewtons).

The Saturn V third stage was designated S-IVB. It was built by Douglas Aircraft Company at Huntington Beach, California. The S-IVB was 58 feet, 7 inches (17.86 meters) tall with a diameter of 21 feet, 8 inches (6.604 meters). It had a dry weight of 23,000 pounds (10,000 kilograms) and fully fueled weighed 262,000 pounds. The third stage had one J-2 engine and also used liquid hydrogen and liquid oxygen for propellant. The S-IVB would place the Command and Service Module into Low Earth Orbit, then, when all was ready, the J-2 would be restarted for the Trans Lunar Injection.

Eighteen Saturn V rockets were built. They were the most powerful machines ever built by man.

Apollo 17 launched 3 years, 4 months, 20 days, 16 hours, 1 minute, 0 seconds after Apollo 11, the first manned flight to The Moon.

Apollo 17 (AS-512) lifts off from Launch Complex 39A at 05:33:00 UTC, 7 December 1972. (NASA)
Apollo 17 (AS-512) lifts off from Launch Complex 39A at 05:33:00 UTC, 7 December 1972. (NASA)
Apollo 17 (NASA S72-55070)

© 2018, Bryan R. Swopes

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5 December 1963

RUSHWORTH, Robert H., Major General, USAF5 December 1963: On Flight 97 of the X-15 Program, Major Robert A. Rushworth flew the number one aircraft, Air Force serial number 56-6670, to an altitude of 101,000 feet 30,785 meters) and reached Mach 6.06 (4,018 miles per hour/6,466 kilometers per hour).

The rocketplane was dropped from the Boeing NB-52B Stratofortress “mother ship” 52-008, Balls 8, flying at 450 knots (833.4 kilometers per hour) at 45,000 feet (13,716 meters) over Delamar Dry Lake, Nevada. Rushworth ignited the Reaction Motors XLR-99-RM-1 rocket engine, which burned for 81.2 seconds before shutting down.

The flight plan had called for an altitude of 104,000 feet (31,699 meters), a 78 second burn and a maximum speed of Mach 5.70. With the difficulties of flying such a powerful rocketplane, Rushworth’s flight was actually fairly close to plan. During the flight the right inner windshield cracked.

Bob Rushworth landed the X-15 on Rogers Dry Lake at Edwards Air Force Base, California, after a flight of 9 minutes, 34.0 seconds.

Mach 6.06 was the highest Mach number reached for an unmodified X-15.

56-6670 flew 81 of the 199 flights of the X-15 Program. It is in the collection of the Smithsonian Institution National Air and Space Museum.

From 1960 to 1966, Bob Rushworth made 34 flights in the three X-15s, more than any other pilot.

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. (Photo by Eric Long, National Air and Space Museum, Smithsonian Institution)
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. (Photo by Eric Long, National Air and Space Museum, Smithsonian Institution)

© 2016, Bryan R. Swopes

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20 November 1940

North American Aviation's NA-73X fighter prototype, engine idling, with Vance Breese in the cockpit at Mines Field, Los Angeles, 26 October 1941. (North American Aviation Inc.)
North American Aviation’s NA-73X fighter prototype, engine idling, with Vance Breese in the cockpit at Mines Field, Los Angeles, 26 October 1940. (North American Aviation Inc.)

20 November 1940: North American Aviation’s Chief Test Pilot, Paul Baird Balfour, made his first flight in the NA-73X, NX19998, prototype for a Royal Air Force fighter, the Mustang Mk.I.

Vance Breese was the free-lance test pilot who made the first seven flights in the new airplane. Breese claimed to have made a bet with North American executives that Balfour would crash the prototype on his first flight.

Paul B. Balfour (1908–1951). This is Balfour’s NAA employee file card. (North American Aviation Inc.)

This flight was scheduled to be a high speed test. Edgar Schmued, the designer, offered to show Balfour around the airplane. “Before this flight, I asked Balfour to get into the airplane and go through the routine of a takeoff and flight. He responded that one airplane is like another and he would not need the routine checkout.”

The ground crew started the NA-73X’s 1,150 horsepower Allison V-1710-39 liquid-cooled V-12 engine at 5:40 a.m. and let it warm up to normal operating temperature. When it was restarted just prior to Paul Balfour’s flight, “it was a little hard to start,” according to Olaf Anderson, the airplane’s mechanic.

The prototype Mustang, NA-73X, lies upside down in a plowed field, 20 November 1941. (North American Aviation Inc.)
The prototype Mustang, NA-73X, lies upside down in a plowed field, 20 November 1940. (North American Aviation Inc.)

Balfour took off from Mines Field at about 7:10 a.m. After about twelve minutes of flight, the Allison stopped running. Balfour was too far from Mines Field to make it back to the runway. He landed in a plowed field west of Lincoln Boulevard. When the tires hit the soft surface, the prototype flipped over. Balfour was not hurt and was able to crawl out of the upside-down wreck.

The Civil Aeronautics Board report described the damage as “engine housing broken, both wingtips damaged, tail surfaces damaged, top of fuselage damaged, and other miscellaneous damage.” The NA-73X had accumulated just 3 hours, 20 minutes of flight.

Vance Breese won his bet.

Paul Balfour was not injured in the crash landing, but the NA-73X prototype was significantly damaged. (North American Aviation Inc.)
Paul Balfour was not injured in the crash landing, but the NA-73X prototype was significantly damaged. (North American Aviation Inc.)

According to the C.A.B. investigation, the engine had stopped due to fuel starvation when Balfour neglected to select another tank.

The prototype was taken back to the factory and rebuilt. It would become the famous Mustang, one of the most significant aircraft of World War II.

Damage to the wingtips, tail surfaces, fuselage. (North American Aviation Inc.)
Damage to the wingtips, tail surfaces, fuselage. (North American Aviation Inc.)

Robert C. Chilton was hired as the new Chief Test Pilot. He would continue testing the Mustang developments throughout the war. Chilton made his first flight in NA-73X on 3 April 1941.

The Mustang prototype was hoisted out of the plowed field and taken back to the factory where it was rebuilt. (North American Aviation Inc.)
The Mustang prototype was hoisted out of the plowed field and taken back to the factory where it was rebuilt. (North American Aviation Inc.)

Paul Balfour continued to work for North American Aviation, testing the NA-40 and NA-40B prototypes and the B-25 Mitchell medium bomber. He later served in the United States Air Force.

Paul Baird Balfour was born 5 July 1908 in Washington State. He was the son of Fred Patrick Balfour and Edna May Baird Balfour. Balfour attended two years of college.

Paul Balfour entered the U.S. Army Air Corps (prior to 1930). He was stationed at Rockwell Field, San Diego, California.

Balfour married Martha Lillette Cushman of Coronado, California, at Yuma, Arizona, 6 June 1930.

Balfour began working as a test pilot for North American Aviation, Inc., 1 March 1936.

On 2 July 1938, he married Lois Tresa Watchman at Kingman, Arizona. They would have two children.

Paul B. Balfour, center, with a North American Aviation B-25 Mitchell medium bomber. (Photograph courtesy of Neil Corbett, Test and Research Pilots, Flight Test Engineers)
Paul B. Balfour, center, with a North American Aviation B-25 Mitchell medium bomber. (Photograph courtesy of Neil Corbett, Test and Research Pilots, Flight Test Engineers)

On 9 November 1951, Major Paul B. Balfour, U.S. Air Force, attached to the 1002nd Inspector General Group at Norton Air Force Base, California, was flying a North American VB-25J, 44-30955, a transport conversion of a B-25J-30-NC Mitchell medium bomber.

Shortly after takeoff, at about 10:00 a.m., the airplane developed engine trouble. Unable to return to Norton, Balfour attempted a belly landing at a small private airfield. Witness saw that the airplane’s left engine was idling, and its propeller was feathered. As he approached, the airplane was blocked by a windbreak of eucalyptus trees bordering U.S. Route 66. Balfour banked away from the trees but the B-25 crashed in an orange grove along Bloomington Avenue in Rialto, approximately 7 miles (11 kilometers) north of Norton.

Balfour, still buckled in his seat, was thrown clear of the burning wreck and landed in the street. One man on board was killed and two others seriously injured. Balfour died in a hospital three hours later. He was 41 years old. Major Balfour was buried at the Inglewood Park Cemetery, Inglewood, California.

Burning wing of North American VB-25J 44-30955, near Rialto, California, 9 November 1951.
Burning wing of North American VB-25J 44-30955, near Rialto, California, 9 November 1951.

© 2016, Bryan R. Swopes

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