B28 nuclear bomb

B28 nuclear bomb. The B28, originally designated the Mark 28, was a thermonuclear weapon developed by the United States during the Cold War. It became a versatile and long-serving component of the United States nuclear arsenal, deployed in several variants for both strategic and tactical roles. Production ran from 1958 to 1966, with the weapon remaining in service until the early 1990s.

Development and design

The development of the B28 was led by the Los Alamos National Laboratory as part of a broader effort to create lighter, more efficient thermonuclear weapon designs following the Castle Bravo test. It utilized a two-stage Teller-Ulam design, with a fission primary triggering a fusion secondary. The weapon's design emphasized safety features, including sophisticated Permissive Action Link (PAL) arming systems and Command Disable System (CDS) technology to prevent unauthorized use. Its development was closely tied to projects like the TX-28 and was influenced by earlier designs such as the Mark 15 nuclear bomb. The final design allowed for a variable yield, selectable by the crew of the delivering aircraft, making it adaptable for different mission profiles against targets like hardened Soviet Union installations or tactical battlefield formations.

Operational history

The B28 entered service with the United States Air Force and the United States Navy in 1958. It was a primary weapon for aircraft like the B-52 Stratofortress, B-47 Stratojet, F-100 Super Sabre, and F-4 Phantom II. During the Cuban Missile Crisis, B28-equipped bombers were placed on high alert as part of the Strategic Air Command's DEFCON 2 posture. The bomb was also deployed extensively in Europe under NATO nuclear sharing agreements, with weapons stored at bases in countries like the United Kingdom, West Germany, Italy, and Turkey. Its operational life saw it carried by numerous aircraft during training and alert duties throughout the Vietnam War era and the later decades of the Cold War, though it was never detonated in combat.

Variants

The B28 was produced in five main variants, differentiated by their fuzing, delivery, and safety configurations. The **B28EX** (External) was a streamlined, low-drag weapon designed for external carriage at high speeds on aircraft like the F-105 Thunderchief. The **B28RE** (Retarded External) featured a parachute retarder for low-altitude delivery. The **B28IN** (Internal) was configured for internal carriage in the bomb bays of strategic bombers such as the B-52 Stratofortress. The **B28FI** (Full Fuzing Internal) and **B28RI** (Retarded Internal) were internal-store variants with comprehensive fuzing options and parachute retardation, respectively, for specialized delivery modes. These variants allowed the single basic weapon design to fulfill roles from high-altitude strategic bombing to low-altitude tactical strike missions.

Specifications

The B28 had a weight of approximately 2,000 to 2,300 pounds, depending on the variant. Its diameter was about 22 inches, with a length ranging from 10 to 14 feet. The weapon's yield was selectable, with a range from 70 kilotons to 1.45 megatons. It was equipped with multiple fuzing options, including airburst, surface burst, and laydown modes, the latter using a parachute to slow its descent and allow the delivering aircraft time to escape. The physics package used a combination of oralloy and plutonium in its primary stage and lithium deuteride in its secondary. Its design incorporated advanced electronics for arming, fuzing, and firing, managed through the Store Control Unit in the aircraft.

Deployment and service

Deployment of the B28 was widespread across the United States and allied nations. It was a key part of the Nuclear Weapons Stockpile managed by the Department of Energy and its predecessor, the Atomic Energy Commission. Under agreements like the NATO nuclear sharing program, B28s were forward-deployed at bases such as RAF Lakenheath and Ramstein Air Base. The weapon was carried by numerous aircraft across Strategic Air Command and Tactical Air Command, and also saw service aboard United States Navy aircraft like the A-3 Skywarrior and A-5 Vigilante. The B28 began to be phased out in the 1980s with the introduction of newer weapons like the B61 nuclear bomb, and the last units were retired from the stockpile in 1991 following the Strategic Arms Reduction Treaty (START) and the end of the Cold War.

Category:American nuclear bombs Category:Cold War nuclear weapons of the United States Category:Nuclear weapons of the United States