MK39 Nuclear Bomb The MK39 was basically an improved MK15 equipped with parachutes to provide more release options for the delivery aircraft. It was carried by B-47 and B-52 bombers. 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. The bomb on display at the National Museum of the United States Air Force was received from the National Atomic Museum at Kirtland Air Force Base, N.M., in 1993. Click here to return to the Cold War Gallery. Find Out More Related Fact Sheets Boeing B-52D Stratofortress Note: The appearance of hyperlinks does not constitute endorsement by the National Museum of the USAF, the U.S. Air Force, or the Department of Defense, of the external website, or the information, products or services contained therein.