25 January 1946

Jack Valentine Woolams, Chief Experimental Test Pilot, Bell Aircraft Corporation. (John Trudell/Ancestry)

25 January 1946:¹ Near Pinecastle Army Airfield in central Florida, Bell Aircraft Corporation Senior Experimental Test Pilot Jack Woolams made the first unpowered glide flight of the XS-1 supersonic research rocketplane, 46-062.

46-062 was the first of three XS-1 rocketplanes built by Bell for the U.S. Army Air Corps and the National Advisory Committee for Aeronautics (NACA) to explore flight at speeds at and beyond Mach 1, the speed of sound. The airplane had been rolled out of Bell’s plant at Buffalo, New York, on 27 December 1945. The rocket engine, which was being developed by Reaction Motors, Inc., at Franklin Lakes, New Jersey, was not ready, so the experimental aircraft was carrying ballast in its place for the initial flight tests.

Jack Woolams with the second Bell XS-1, 46-063. (Niagara Aerospace Museum)

The XS-1 was to be air-dropped from altitude by a modified heavy bomber so that its fuel could be used for acceleration to high speeds at altitude, rather than expended climbing from the surface. Bell manufactured B-29B Superfortresses at its Atlanta, Georgia, plant and was therefore very familiar with its capabilities. A B-29, 45-21800, was selected as the drop ship and modified to carry the rocketplane in its bomb bay.

Boeing B-29-96-BW Superfortress 45-21800 carries a Bell XS-1 rocketplane. (Bell Aircraft Museum)

Pinecastle Army Airfield was chosen as the site of the first flight tests because it had a 10,000 foot (3,048 meter) runway and was fairly remote. There was an adjacent bombing range and the base was a proving ground for such aircraft as the Consolidated B-32 Dominator. (Today, Pinecastle A.A.F. is known as Orlando International Airport, MCO.)

Bell XS-1 46-062 was placed in a pit at Pinecastle A.A.F. so that the B-29 drop ship in the background could be positioned over it. (NASA)
Bell XS-1 46-062 was placed in a pit at Pinecastle A.A.F. so that the B-29 drop ship in the background could be positioned over it. (NASA)

The B-29 carrying the XS-1 took off from Pinecastle at 11:15 a.m., and began its climb to altitude. Woolams was in the forward crew compartment. As the bomber reached approximately 10,000 feet (3,048 meters), he entered the bomb bay and climbed down into the cockpit of the research aircraft. At the drop altitude, the B-29 was flying at 180 miles per hour (290 kilometers per hour) with the inboard propellers feathered and flaps lowered to 20°.

The XS-1 dropped away smoothly. Woolams flew the rocketplane to a maximum 275 miles per hour (443 kilometers per hour), indicated air speed, during this first glide test. He described the rocketplane as, “solid as a rock, experiencing absolutely no vibration or noise. At the same time, it felt as light as a feather during maneuvers due to the lightness, effectiveness and nice balance between the controls.” Woolams described the visibility from the cockpit as “not good, but adequate.”

The duration of the first glide flight was about ten minutes. Woolams misjudged his approach to Pinecastle and landed slightly short of the runway, on the grass shoulder, but the XS-1 was not damaged.

The conclusion of Woolams’ flight report is highly complementary of the experimental airplane:

11.  Of all the airplanes the writer has flown, only the XP-77 and the Heinkel 162 compare with the XS-1 for maneuverability, control relationship, response to control movements, and lightness of control forces. Although these impressions were rather hastily gained during a flight which lasted only 10 minutes, it is the writer’s opinion that due to these factors and adding to them the security which the pilot feels due to the ruggedness, noiselessness, and smoothness of response of this airplane, it is the most delightful to fly of them all.

—PILOT’S REPORT, Flight 1, by Jack Woolams

Jack Woolams made ten glide flights with 46-062, evaluating its handling characteristics and stability. The aircraft was returned to Bell to have the rocket engine installed, and it was then sent to Muroc Army Airfield in the high desert of southern California for powered flight tests. (Muroc A.A.F. was renamed Edwards Air Force Base in 1949.)

Bell XS-1 46-062 was later named Glamorous Glennis by its military test pilot, Captain Charles E. Yeager, U.S. Army Air Corps. On 14 October 1947, Chuck Yeager flew it to Mach 1.06 at 13,115 meters (43,030 feet). Today the experimental aircraft is on display at the Smithsonian Institution National Air and Space Museum.

The Bell XS-1, later re-designated X-1, was the first of a series of rocket-powered research airplanes which included the Douglas D-558-II Skyrocket, the Bell X-2, and the North American Aviation X-15, which were flown by the U.S. Air Force, U.S. Navy, NACA and its successor, NASA, at Edwards Air Force Base to explore supersonic and hypersonic flight and at altitudes to and beyond the limits of Earth’s atmosphere.

An X-1 under construction at teh Bell Aircraft Corporation plant, Buffalo, New York. (Bell Aircraft Corporation)
An X-1 under construction at the Bell Aircraft Corporation plant, Buffalo, New York. (Bell Aircraft Corporation)

The X-1 has an ogive nose, similar to the shape of a .50-caliber machine gun bullet, and has straight wings and tail surfaces. It is 30 feet, 10.98 inches (9.423 meters) long with a wing span of 28.00 feet (8.534 meters) and overall height of 10 feet, 10.20 inches (3.307 meters).

46-062 was built with a thin 8% aspect ratio wing, while 46-063 had a 10% thick wing. The wings were tapered, having a root chord of 6 feet, 2.2 inches (1.885 meters) and tip chord of 3 feet, 1.1 inches (0.942 meters), resulting in a total area of 130 square feet (12.1 square meters). The wings have an angle of incidence of 2.5° with -1.0° twist and 0° dihedral. The leading edges are swept aft 5.05°.

The horizontal stabilizer has a span of 11.4 feet (3.475 meters) and an area of 26.0 square feet (2.42 square meters). 062’s stabilizer has an aspect ratio of 6%, and 063’s, 5%.

The fuselage cross section is circular. At its widest point, the diameter of the X-1 fuselage is 4 feet, 7 inches (1.397 meters).

46-062 had an empty weight is 6,784.9 pounds (3,077.6 kilograms), but loaded with propellant, oxidizer and its pilot with his equipment, the weight increased to 13,034 pounds (5,912 kilograms).

The X-1 was designed to withstand an ultimate structural load of 18g.

Front view of a Bell XS-1 supersonic research rocketplane at the Bell Aircraft plant, Buffalo, New York. (Bell Aircraft Museum)

The X-1 was powered by a four-chamber Reaction Motors, Inc., 6000C4 (XLR11-RM-3 ) rocket engine which produced 6,000 pounds of thrust (26,689 Newtons). This engine burned a 75/25 mixture of ethyl alcohol and water with liquid oxygen. Fuel capacity is 293 gallons (1,109 liters) of water/alcohol and 311 gallons (1,177 liters) of liquid oxygen. The fuel system was pressurized by nitrogen at 1,500 pounds per square inch (103.4 Bar).

The X-1 was usually dropped from the B-29 flying at 30,000 feet (9,144 meters) and 345 miles per hour (555 kilometers per hour). It fell as much as 1,000 feet (305 meters) before beginning to climb under its own power.

The X-1’s performance was limited by its fuel capacity. Flying at 50,000 feet (15,240 meters), it could reach 916 miles per hour (1,474 kilometers per hour), but at 70,000 feet (21,336 meters) the maximum speed that could be reached was 898 miles per hour (1,445 kilometers per hour). During a maximum climb, fuel would be exhausted as the X-1 reached 74,800 feet (2,799 meters). The absolute ceiling is 87,750 feet (26,746 meters).

Bell X-1 46-062 on the dry lake bed at Muroc Army Airfield, circa 1947. (NASM)

The X-1 had a minimum landing speed of 135 miles per hour (217 kilometers per hour) using 60% flaps.

There were 157 flights with the three X-1 rocket planes. The number one ship, 46-062, Glamorous Glennis, made 78 flights. On 26 March 1948, with Chuck Yeager again in the cockpit, it reached reached Mach 1.45 (957 miles per hour/1,540 kilometers per hour) at 71,900 feet (21,915 meters).

The third X-1, 46-064, made just one glide flight before it was destroyed 9 November 1951 in an accidental explosion.

The second X-1, 46-063, was later modified to the X-1E. It is on display at the NASA Dryden Research Center at Edwards Air Force Base. Glamorous Glennis is on display at the Smithsonian Institution National Air and Space Museum, next to Charles A. Lindbergh’s Spirit of St. Louis.

Bell X-1, 46-062, Glamorous Glennis, on display at the National Air and Space Museum, Washington, D.C. (NASM)
Bell X-1 46-062, Glamorous Glennis, on display at the National Air and Space Museum, Washington, D.C. (NASM)

Jack Valentine Woolams was born on Valentine’s Day, 14 February 1917, at San Francisco, California. He was the second of three children of Leonard Alfred Woolams, a corporate comptroller, and Elsa Mathilda Cellarius Woolams. He grew up in San Rafael, California, and graduated from Tamalpais School in 1935.

Jack Woolams, 1941

After two years of study at The University of Chicago, in 1937 Woolams entered the Air Corps, U.S. Army, as an aviation cadet. He trained as a pilot at Kelly Field, San Antonio, Texas. On graduation, 16 June 1938, he was discharged as an aviation cadet and commissioned as a second lieutenant, Air Reserve. He was assigned to Barksdale Army Air Field, Louisiana, where he flew the Boeing P-26 and Curtiss P-36 Hawk.

On 10 February 1939, Lieutenant Woolams was one of three Air Corps officers thrown into the waters of Cross Lake, near Shreveport, Louisiana, when the boat, owned by Woolams, capsized in 4 foot (1.2 meters) waves. Woolams and Lieutenant J.E. Bowen were rescued after 4 hours in the water, but the third man, Lieutenant Wilbur D. Camp, died of exposure.

Lieutenant Woolams transferred from active duty to inactive reserve status in September 1939 in order to pursue his college education at The University of Chicago, where he was a member of the Alpha Delta Phi (ΑΔΦ) fraternity. While at U. of C., he played on the university’s football and baseball teams, and was a member of the dramatic society. Woolams graduated 18 July 1941 with a Bachelor of Arts (A.B.) degree in Economics.

Mr. and Mrs. Jack V. Woolams, 16 June1941. (Unattributed)

Jack Woolams married Miss Mary Margaret Mayer at the bride’s home in Riverside, Illinois, 16 June 1941. They would have three children. Miss Mayer was also a 1941 graduate from the University of Chicago. She had been Woolams’ student in the Civilian Pilot Training Program.

Woolams became a production test pilot for the Bell Aircraft Corporation at Buffalo, New York. He tested newly-built Bell P-39 Airacobra fighters. As he became more experienced, he transitioned to experimental testing with the P-39, P-63 King Cobra, and the jet-powered P-59 Airacomet.

Jack Valentine Woolams, Chief Experimental Test Pilot, Bell Aircraft Corporation, circa 1946. (Niagara Aerospace Museum)

On 28 September 1942, Jack Woolams flew a highly-modified Bell P-39D-1-BE Airacobra, 41-38287, from March Field, near Riverside, California, to Bolling Field, Washington, D.C., non-stop. The duration of the flight was approximately 11 hours. The modifications were intended to allow P-39s to be flown across the Pacific Ocean to Hawaii and on to the Soviet Union for delivery under Lend Lease.

During the summer of 1943, Woolams flew the first Bell YP-59A Airacomet, 42-108771, to an altitude of 47,600 feet (14,508 meters) near Muroc Army Air Field in California.

On 5 January 1945, Woolams was forced to bail out of a Bell P-59A-1-BE, 44-22616. He suffered a deep laceration to his head as he left the airplane. He lost his flight boots when the parachute opened, and on landing, had to walk barefoot through knee-deep snow for several miles to reach a farm house. The deep snow prevented the company’s ambulance from getting to Woolams. Bell Aircraft president Lawrence D. Bell sent the company’s second prototype Bell Model 30 helicopter, NX41868, flown by test pilot Floyd Carlson, to transport a doctor, J.A. Marriott, M.D., to the location. Another Bell test pilot, Joe Mashman, circled overhead in a P-63 King Cobra to provide a communications link. Later in the day, an ambulance was able to get through the snow to take Woolams to a hospital.

Wreckage of Bell P-59A-1-BE Airacomet 44-22616. Jack Woolams bailed out of this airplane 5 January 1945. (Niagara Aerospace Museum)

Woolams was scheduled to make the first powered flight of the XS-1 during October 1946.

Jack Woolams was killed Friday, 30 August 1946, when his red Thompson Trophy racer, Cobra I, a modified 2,000-horsepower Bell P-39Q Airacobra, crashed into Lake Ontario at over 400 miles per hour. His body was recovered by the U.S. Coast Guard four days later.

Bell Aircraft Corporation experimental test pilots Jack Woolams and Tex Johnston with their modified Bell P-39Q Airacobras, Cobra I and Cobra II. (Niagara Aerospace Museum)

¹ This article was originally dated 19 January 1946. There were known discrepancies as to the date of the first flight from various reliable sources. Recently discovered test flight reports, provided to TDiA by Mr. Roy T. Lindberg, Historian of the Niagara Aerospace Museum, Niagara Falls, New York, have confirmed that the date of the first flight was actually 25 January 1946. The article has been been revised accordingly, as well as to incorporate new information from these reports.

TDiA is indebted to Mr. Lindberg for providing this and other documentation.

© 2019, Bryan R. Swopes

24 January 1975

Aérospatiale SA 365 C Dauphin 2, F-WVKE. (Vertical Flight Society)

24 January 1975: First flight Aérospatiale SA 365 C Dauphin 2 prototype, F-WVKE, s/n 004. This prototype was built from a single engine SA 360 C Dauphin.

The SA 365 C is a single main rotor/fenestron twin-engine medium helicopter. It is operated by a single pilot seated in the right seat, and can carry a maximum of 13 passengers. The four-bladed articulated main rotor has a diameter of 11.68 meters (38.31 feet) and turns clockwise as seen from above. (The advancing blade is on the left.) A 0.89 meter (2.95 feet), 13-bladed fenestron provides anti-torque and yaw control.¹ In 1977, a Star Flex rigid rotor hub replaced the articulated main rotor.

The fuselage is 10.98 meters (36.02 feet) long, 3.17 meters (10.40 feet) wide and 3.27 meters (10.72 feet) high. In the original configuration, the Dauphin 2 had fixed wheeled landing gear. The second prototype was used to experiment with retractable tricycle gear, which was adopted with the SA 365 N.

Aérospatiale SA 365 C Dauphin 2, F-WVKE. (Vertical Flight Society)

The SA 365 C was powered by two Turboméca Arriel 1A turboshaft engines. These had a maximum continuous power rating of 430 kW (577 h.p.) @ 50,764 r.p.m.; 466 kW (625 h.p.) for take off (5-minute limit) @ 52,007 r.p.m./or one engine inoperative (30-minute limit); and 486 kW (652 h.p.) @ 52,680 r.p.m., one engine inoperative,  2½-minute limit.

The main rotor turns 350 r.p.m. (+/- 10) in normal operation. The minimum transient speed to 285 r.p.m., is allowed in case of engine failure, and 320–420 r.p.m. during autorotation.

The helicopter’s maximum mass is 3,400 kilograms (7,496 pounds, maximum gross weight). Its maximum speed (VNE)  is 315 kilometers per hour (170 knots), and maximum operating altitude, 4,572 meters (15,000 feet). Fuel capacity is 640 liters (3 liters are unusable).

Fifty SA 365 C and C1 helicopters were built before being replaced by the SA 365 N Dauphin.

¹ The ducted fenestron is more effective than a conventional tail rotor, provides less drag in forward flight, and is safer when operating near the ground.

© 2022, Bryan R. Swopes

24 January 1963

Boeing B-52C-40-BO Stratofortress 53-400, the same type as 53-406, which crashed on Elephant Mountain, 24 January 1963. (San Diego Air & Space Museum)

24 January 1963: A Boeing B-52C-40-BO Stratofortress, 53-0406, call sign “Frosh 10,” of the 99th Bombardment Wing, Heavy, was conducting a low-altitude training flight using terrain-following radar. Eight crewmen were aboard. Flying at or below 500 feet (152 meters) above ground level (AGL) and at 280 knots (322 miles per hour, 519 kilometers per hour) the bomber encountered wind gusts of up to 40 knots (21 meters per second).

As the turbulence became severe, the aircraft commander, Lieutenant Colonel Dante E. Bulli, began a climb to avoid it. At approximately 2:52 p.m., EST, however, the vertical fin attachment failed and the B-52 began rolling to the right and pitching down. Colonel Bulli, unable to control the airplane, ordered the crew to abandon the bomber.

B-52C 53-0406 crashed into the west side of Elephant Mountain, a 3,774 foot (1,150 meters) forest-covered mountain, 6 miles (10 kilometers) from Greenville, Maine. Only three men, Colonel Bulli, co-pilot Major Robert J. Morrison and navigator Captain Gerald J. Adler, were able to get out of the B-52, but Major Morrison died when he hit a tree. Lieutenant Colonel Joe R. Simpson, Jr., Major William W. Gabriel, Major Robert J. Hill, Jr., Captain Herbert L. Hansen, Captain Charles G. Leuchter and Technical Sergeant Michael F. O’Keefe were also killed.

Large sections of Frosh 10 are still on Elephant Mountain. The crash site is a popular hiking destination.

The Boeing B-52 Stratofortress had been designed as a very high altitude penetration bomber, but changes in Soviet defensive systems led to a change to very low altitude flight as a means of evading radar. This was subjecting the airframes to unexpected stresses. Several crashes resulted from structural failures during turbulence.

Less than one year later, Boeing was conducting flight tests of the B-52 in turbulence, using a highly-instrumented B-52H. That airplane also lost its vertical fin when it encountered severe turbulence in Colorado. The Boeing test pilots aboard were able to save the bomber and landed it six hours later.

Boeing B-52H-170-BW Stratofortress 61-023, "Ten-Twenty-Three", after losing the vertical fin, 10 January 1964. (Boeing)
Boeing B-52H-170-BW Stratofortress 61-023, “Ten-Twenty-Three”, after losing the vertical fin, 10 January 1964. (Boeing)
Colonel Dante E. Bulli, United States Air Force

Dante E. Bulli was born at Cherry, Illinois, 17 July 1922, the second child of Italian immigrants Giovanni Bulli, a salesman, and Anna Gareto Bulli.  He attended Hall High School before working on the aircraft assembly lines of the Lockheed Aircraft Company in California.

Bulli enlisted as an aviation cadet in the U.S. Army Air Corps in 1942. He was commissioned as a second lieutenant, Army of the United States, 5 December 1943, and promoted to first lieutenant, 5 December 1946.

In 1947 Lieutenant Bulli married Miss Evelyn Lewis, also from Cherry, Illinois.

“Dan” Bulli was a combat veteran of World War II, the Korean War and the Vietnam War. He flew B-24 Liberators, the B-29 Superfortress and B-52 Stratofortress. He retired from the Air Force in 1974.

Colonel Dante E. Bulli died at Omaha, Nebraska, 30 December 2016, at the age of 94 years.

© 2018, Bryan R. Swopes

24 January 1962

Sanford N. ("Sandy") McDonnell hands over the keys to the first F-110A Spectre to the United States Air Force, St. Louis, Missouri, 24 January 1962. (McDonnell Aircraft Corporation)
Sanford N. (“Sandy”) McDonnell hands over the keys to the first F-110A Spectre to the United States Air Force, St. Louis, Missouri, 24 January 1962. (McDonnell Aircraft Corporation)

24 January 1962: The McDonnell Aircraft Corporation delivered the first F-110A Spectre to Colonel Gordon Graham and Colonel George Laven, United States Air Force, at the McDonnell plant at St. Louis, Missouri. The F-110A was soon redesignated as the F-4C Phantom II.

Two Phantoms were delivered to the Air Force for evaluation at Langley Field, Virginia. They were U.S. Navy F4H-1 Phantom IIs, Bureau of Aeronautics serial numbers 149405 and 149406. Initially the aircraft retained the Navy serial numbers but eventually were assigned Air Force numbers 62-12168 and 62-12169. The Air Force bailed them back to McDonnell to develop the YF-4C prototypes.

62-12169 (ex-Bu. No. 149406) was converted to a JF-4B (a special test aircraft). Operated by the McDonnell-Douglas Aircraft Center at Holloman Air Force Base, New Mexico, it suffered an engine explosion, 8 March 1967. McDonnell test pilot Charles (“Pete”) Garrison successfully ejected. The airplane crashed and was destroyed.

McDonnell Aircraft Corporation F-110A Spectre 149405. (McDonnell Aircraft Corporation)
McDonnell Aircraft Corporation F-110A Spectre 149405. (McDonnell Aircraft Corporation)
U.S. Air Force F-110A Spectre with bomb load.
U.S. Air Force F-110A Spectre 149405 armed with AIM-101 Sparrow missiles and Mk.82 500-pound bombs. (McDonnell Aircraft Corporation)
U.S. Air Force F-110A Spectre 149405 armed with AIM-101 Sparrow missiles and Mk.82 500-pound bombs. (NARA)

McDonnell built 5,057 Phantom IIs. They served with the United States Navy and Marine Corps, the U.S. Air Force, and many allied nations. The last Phantom II, an F-4E, was completed 25 October 1979. The U.S. Air Force retired its last operational Phantoms from service 20 December 2004, 42 years, 10 months, 27 days after receiving the first F-110A.

McDonnell F-110A Spectre 149405 (F4H-1, F-4B-9i, and F-4C-15-MC 62-12168).
McDonnell F-110A Spectre 149405 (F4H-1, F-4B-9i-MC, and finally, F-4C-15-MC 62-12168). (McDonnell Aircraft Corporation)
McDonnell F-110A 149406 at Nellis Air Force Base, March 1962. (NARA)
McDonnell F-4C-15-MC Phantom IIs 149405 and 149406, circa 1963. (NARA)
McDonnell F-110A 149405 and 149406 in formation near Lambert Field, St. Louis, Missouri. (NARA)

© 2018, Bryan R. Swopes

24 January 1961

Boeing B-52G-75-BW Stratofortress 57-6471, similar to 58-0187. The numeral "3" on the vertical fin and the white cross-in-back square on the top of the fuselage identify this B-52 as a Boeing flight test aircraft. (U.S. Air Force)
Boeing B-52G-75-BW Stratofortress 57-6471, similar to 58-0187. The numeral “3” on the vertical fin and the white cross-in-back square on the top of the fuselage identify this B-52 as a Boeing flight test aircraft. (U.S. Air Force)

24 January 1961: “Keep 19,” a Boeing B-52G-95-BW Stratofortress, serial number 58-0187, of the 4241st Strategic Wing, was on a 24 hour airborne alert mission off the Atlantic Coast of the United States. The bomber was commanded by Major Walter S. Tulloch, U.S. Air Force, with pilots Captain Richard W. Hardin and First Lieutenant Adam C. Mattocks. Other crewmembers were Major Eugene Shelton, Radar Navigator; Captain Paul E. Brown, Navigator; First Lieutenant William H. Wilson, Electronics Warfare Officer; Major Eugene H Richards, Electronics Warfare Instructor; Technical Sergeant Francis R. Barnish, Gunner. It was armed with two Mark 39 thermonuclear bombs, each with an explosive yield of 3–4 megatons.

The B-52 refueled in flight from an air tanker. The tanker’s crew notified Major Tulloch that the B-52’s right wing was leaking fuel. The leak was severe and more than 5,400 gallons (37,000 pounds/17,000 kilograms) of jet fuel was lost in less than three minutes. The B-52 headed for Seymour Johnson Air Force Base in North Carolina.

Boeing B-52G-95-BW Stratofortress 58-0190, the same type as Keep 19. (U.S. Air Force)

As they descended, the unbalanced condition made the bomber increasingly difficult to control. The bomber went out of control and Major Tulloch ordered the crew to abandon the doomed ship. Five crewmen ejected and one climbed out through the top hatch. (Lieutenant Mattocks is believed to be the only B-52 crewmember to have successfully escaped through the upper hatch.)

58-0187 broke apart and exploded. Its wreckage covered a two square mile (5.2 square kilometers) area. Three crewmen, Majors Shelton and Richards, and Sergeant Barnish, were killed.

As the B-52 broke up, its two Mark 39 bombs fell free of the bomb bay. One buried itself more than 180 feet (55 meters) deep. The other’s parachute retarding system operated properly and it touched down essentially undamaged. It was quickly safed by an explosive ordnance team and hauled away.

One of teh two Mk 39 bombs that fell from the B-52 as it broke up near Goldsboro, South Carolina, 24 January 1961.
One of the two Mk 39 bombs that fell from the B-52 as it broke up near Goldsboro, North Carolina, 24 January 1961. The parachute retarding  system had deployed, allowing the bomb to touch down with minimal damage.

Recovery of the buried bomb was very difficult. After eight days, the ordnance team had recovered most of the bomb, including the 92 detonators and conventional explosive “lenses” of the “primary,” the first stage implosion section. The uranium-235/plutonium-239 “pit”—the very core of the bomb— was recovered on 29 January. The “secondary,” however, was never found.

Most of the Mark 39 bomb was uncovered from an excavation at the farm field near Goldsboro, North Carolina. (U.S. Air Force)

The secondary contains the fusion fuel, but it cannot detonate without the explosion of the primary. Although the secondary remains buried, there is no danger of an explosion.

“During a B-52 airborne alert mission structural failure of the right wing resulted in two weapons separating from the aircraft during aircraft breakup at 2,000 – 10,000 feet altitude. One bomb parachute deployed and the weapon received little impact damage. The other bomb fell free and broke apart upon impact. No explosion occurred. Five of the eight crew members survived. A portion of one weapon, containing uranium, could not be recovered despite excavation in the waterlogged farmland to a depth of 50 feet. The Air Force subsequently purchased an easement requiring permission for anyone to dig there. There is no detectable radiation and no hazard in the area.”

An accident of this type, involving the loss of nuclear weapons is known by the military code name BROKEN ARROW. Though official statements were that there was no danger that either of the bombs could have exploded, others indicate that five of the six steps (or six of seven) required for a thermonuclear detonation did occur. Only the aircraft commander’s arming switch had not been activated.

Bomb, Mark 39Y1 Mod 2, P/N 300611-00, serial number 4215, at the National Museum of the United States Air Force. Behind it is a Convair B-36 Peacemaker ten-engine strategic bomber. (U.S. Air Force)

The Mark 39 was a two-stage, radiation-implosion thermonuclear bomb. It was in production from 1957–1959, with more than 700 built. It was fully fused, meaning it could be detonated by contact with the ground, as an air burst, or “lay down”— a series of parachutes would slow the bomb and it would touch down on its target before detonating. This allowed the bomber time to get clear.

The Mark 39 was considered a light weight weapon, weighing 6,500–6,750 pounds (2,950–3,060 kilograms). The bomb’s length was approximately 11 feet, 8 inches (3.556 meters), with a diameter of 2 feet, 11 inches (0.889 meters). The explosive yield of the Mark 39 was 3–4 megatons. (For reference, the 1956 nuclear weapons test at Bikini Atoll, Redwing Cherokee, had a yield of 3.8 megatons.)

Fireball from detonation of TX-15 weapon, Operation Redwing Cherokee, 21 May 1956. (Nuclear Weapons Archive)

The Mark 39 was withdrawn from service in the mid-1960s and replaced with the more powerful Mk 41.

© 2018, Bryan R. Swopes