Mark 17 nuclear bomb
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The Mark 17 and Mark 24 were the first mass-produced hydrogen bombs deployed by the United States. The two differed in their "primary" stages. The MK 17/24 bombs were 24 feet 8 inches (7.52 m) long, 61.4 inches (1.56 m) diameter. They weighed 21 tons. The Mark 17 had a yield in the range of 25 megatons TNT equivalent. Total production of Mk 17s was 200, and there were 105 Mk 24s produced, all between October 1954 and November 1955.
Design and development originated when Los Alamos National Laboratory proposed that a bomb design using lithium deuteride with non-enriched lithium was possible. The new design was designated TX-17 on February 24, 1953. The TX-17 and 24 were tested as the "Runt" (Castle Romeo shot) device during Operation Castle in 1954. After the successful tests, basic versions of the Mk-17 and 24 were deployed as part of the "Emergency Capability" program. A total of 5 EC 17 and 10 EC 24 bombs were rushed into stockpile between April and October 1954. The EC weapons lacked parachutes to delay the time between release and their detonation, ensuring the delivery aircraft would be destroyed with the target. Other safety features such as In Flight Insertion (IFI) and safe arming and fusing devices were also omitted to ensure a quick thermonuclear capability.
The EC weapons were quickly replaced with MK 17 Mod 0 and Mk-24 Mod 0 bombs in October and November 1954. Those weapons included a 64-foot-diameter (20 m) parachute to allow the delivery aircraft to escape. With the addition of IFI of the Primary capsule to prevent a nuclear explosion in case of an accident, the weapons were upgraded to the Mod 1 standard. The inclusion of a contact fuse upgraded some bombs to the Mod 2 version, allowing the bombs to be used against "soft" targets (air burst), or buried targets such as command bunkers (contact burst).
Due to the introduction of smaller and lighter weapons such as the Mk 15, as well as the pending retirement of the only aircraft capable of carrying them, the B-36, the Mk 24s were withdrawn by October 1956, with the Mk-17s withdrawn by August 1957.
The Mk 17 was not the first hydrogen bomb stockpiled by the United States. Five examples of the EC14 "Alarm Clock" were prepared for possible use starting in February 1954. There were also five examples of the EC16 "Jughead" cryogenic bomb, a direct development of the "Mike" device produced, starting in January 1954, before the EC17/24 bombs. The EC14s with drogue chutes became Mk 14 bombs and were the first in the hydrogen bomb in the stockpile starting in October 1954. The EC16s were never in the stockpile and were the first EC weapons eliminated. There was only 1 B-36 converted under Project Bar Room to carry the Jughead.
On May 27, 1957 a Mark 17 was unintentionally jettisoned from a B-36 just south of Albuquerque, NM's Kirtland AFB. The device fell through the closed bomb bay doors of the bomber, which was approaching Kirtland at an altitude of 1,700 feet. The device's conventional explosives destroyed it on impact, leaving a crater 25 ft in diameter and 12 ft deep. Though a chain reaction was impossible, because the plutonium pits were stored separately on the plane, the incident spread radioactive contamination and debris over a mile-wide area. Although the military cleaned up the site in secret, a few fragments of the bomb - some radioactive still - may be found in the area. It is one of more than 30 known "Broken Arrow" incidents involving the accidental loss or destruction of a nuclear weapon.
Five MK 17/24 casings are on display to the public:
- National Atomic Museum located at Albuquerque, New Mexico.
- The Strategic Air Command Memorial at Naval Air Station Fort Worth Joint Reserve Base at Carswell Field in Fort Worth, Texas.
- The National Museum of the United States Air Force in Dayton, Ohio has a Mk 17/24 casing on display in its Cold War Hangar.
- The Strategic Air and Space Museum in Ashland, Nebraska.
- Castle Air Museum, Atwater, Ca
- Hansen, Chuck. U.S. Nuclear Weapons. Arlington, Texas, Areofax, Inc., 1988. ISBN 0-517-56740-7.
- Gibson, James N. "Nuclear Weapons of the United States," Altglen, PA, Schiffer Publishing, 1996, ISBN 0-7643-0063-6.
- Cochran, Thomas, Arkin, William, Hoenig, Milton "Nuclear Weapons Databook, Volume I, U.S. Nuclear Forces and Capabilities," Cambridge, Massachusetts, Ballinger Pub. Co., 1984, ISBN 0-88410-173-8.
- Hansen, Chuck, "Swords of Armageddon," Sunnyvale, CA, Chucklea Publications, 1995.
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