B39 / Mk.39 / W39

The Mark 39 had a yield of 3.8 Mt. It was an improved version of the bomb Mark 15. The Mark 15 was the first relatively light thermonuclear bomb in the United States. The MK39 was basically an improved MK15 (TX-15-X3 and Mark 39 Mod 0 had the same design) equipped with parachutes to provide more release options for the delivery aircraft. The Mark 39 fusion bomb and the W39 warhead were created on the basis of the same thermonuclear explosive, and were in service from 1957 to 1966. It was carried by B-47 and B-52 bombers. The physics package of the W39 had a diameter of 89 cm and a length of 270 cm, weighed 2830 - 2900 kg. Development of the MK39 began in 1955 and the first bombs entered the national inventory in 1957. The MK39 featured a shock-absorbing aluminum honeycomb nose and used four parachutes for retarded deliveries. A six-foot pilot chute began the sequential deployment of a 28-foot drogue chute, a 68-foot deceleration chute, and finally a 100-foot main canopy. The MK39 weighed 10,000 pounds and had an explosive yield measured in megatons (a megaton is equal to one million tons of TNT). The last MK39 was removed from service in 1966. It was installed on the SM-62 Snark cruise missile and Redstone ballistic missile. On January 24, 1961, the B-52 Stratofortress bomber with two bombs Mark 39 crashed in North Carolina, near the town of Goldsboro.