Mark 7 nuclear bomb

Mark 7 nuclear bomb at USAF Museum

Mark 7 "Thor" (or Mk-7') was the first tactical fission bomb adopted by US armed forces. It was also the first weapon to be delivered using the toss method with the help of the low-altitude bombing system (LABS). The weapon was tested in Operation Buster-Jangle. To facilitate external carry by fighter-bomber aircraft, Mark 7 was fitted with retractable stabilizer fins. The Mark 7 warhead (W7) also formed the basis of the 30.5 inches (775 mm) BOAR rocket, the Mark 90 Betty nuclear depth charge, MGR-1 Honest John rocket, and MGM-5 Corporal ballistic missile. It was also supplied for delivery by Royal Air Force Canberra aircraft assigned to NATO in Germany under the command of SACEUR. This was done under the auspices of Project E, an agreement between the United States and the UK on the RAF carriage of US nuclear weapons. In UK use it was designated 1,650 lb. H.E. M.C. The Mark 7 was in service from 1952 to 1967(8) with 1700–1800 having been built.

Bomb construction

The Mark 7 nuclear weapon weighed approximately 1,600 pounds (730 kg). It was fitted with one vertical retractable stabilizer fin that allowed it to fit better in or under some planes. This was unique, and made it one of the first nuclear weapons to be streamlined enough to be carried on smaller planes. The bomb’s diameter is a total of 30 inches (760 mm). It used a 92-point HE detonation system to initiate implosion and nuclear fission.

Design

See also: Nuclear weapon design

The Mark 7 was a variable yield implosion-type fission weapon using an implosion system with 92 high explosive lenses. The weapon had multiple yields of 8, 19, 22, 30, 31, and 61 kt by using different weapon pits. The weapon had both an airburst and contact fuzing modes. The later versions of this missile used a PAL A type arming and safing system. Approximately 1700 to 1800 Mk7 bombs and 1350 W7 warheads were produced.

Diagram of implosion system used in the Mk7

Delivery system

There were 10 different types of this bomb produced, and due to this there were several different delivery systems. Often the bomb was carried on fighter jets or other types of planes due to the low range of the weapon, such as the F-84, F-100, F-101, and the B-57 planes.

Tests

During Operation Teapot MET a test was conducted using a TX-7E warhead using a composite plutonium/U-233 pit, producing a 22kt yield, 33% lower than expected. As Shot MET was a military effects test the lower yield ruined many of the experiments being conducted during the test. The DoD had not been informed of the substitution by Los Alamos.

Survivors

A Mark 7 casing is on display in the Cold War hangar at the National Museum of the United States Air Force in Dayton, Ohio.

Specifications

• Length: 15.2 feet (4.6 m)
• Diameter: 2.5 feet (0.76 m)
• Weight: 1,680 pounds (762 kg)
• Fuzing: airburst or contact
• Yield: variable yield between 8 and 61 kilotonnes of TNT (33 and 255 TJ)
• Implosion nuclear weapon

Users

A Douglas A4D-2 carrying a Mk 7 bomb on the USS Saratoga in the early 1960s.

• English Electric Canberra (Royal Air Force)
• Douglas F3D-2B Skyknight
• Douglas A-1 Skyraider
• Douglas A-3 Skywarrior
• Douglas A-4 Skyhawk
• Martin B-57 Canberra
• McDonnell F2H Banshee
• McDonnell F3H Demon
• McDonnell F-101 Voodoo
• North American FJ Fury
• North American B-45 Tornado
• North American F-100 Super Sabre
• Republic F-84 Thunderjet

See also

• List of nuclear weapons

External links

• SAC: Nuclear Weapons