MK39

mk39-2.jpg (76361 bytes)
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Width: ~ 35 inches
Length: ~ 140 inches
Weight: ~ 6,700 pounds
Yield: ~ 3-4 MT
Total number produced: 700                 Retired in 1966


     "The MK39 was essentially an improved MK15 with a drogue parachute system for surface-burst capability against hardened targets. It was intended to be a lighter, higher-yield MK15 with a new boosted primary. The MK39 Mod 0 was design-released by Sandia in April 1956, and a prototype MK 39 was fired during Operation REDWING later in the summer. . Initial units of the MK39, described as an "improved, lightweight version of the Class C thermonuclear bomb," were produced in February 1957. On November 18, 1957, the Air Force notified the DMA that SAC had an urgent military requirement for a low-altitude deliverable "laydown" MK39 bomb. Early in March 1958, the MLC requested the AEC to develop an advanced "laydown" design; this project was assigned to LASL and became the MK39-Y1 Mod2 bomb. Wind tunnel tests of the MK39-Y1 Mod 2 were completed by October 1958. ..

     The "laydown" MK39 was dubbed the "Lone Star" project; the bomb was encased in a large semi-rectangular "boat" lined on its bottom with aluminum honeycomb to absorb impact. The whole assembly weighed 7,500 lbs. and was slowed to a ground impact speed of 30 feet per second by a 130-foot diameter parachute (the largest ever fabricated at that time). The "Lone Star" was to be dropped from an altitude of 1,000 feet by B-47 or B-52 bombers. The project was canceled when it was superseded by MK28 and MK43 "laydown" weapons. Approximately 700 MK39s in Mods0, 1, and 2 were manufactured between February 1957 and March 1959; all were retired between January 1962 and November 1966. ..

     The MK39 was designed to be very safe, reliable, and simple. It could be readied for combat quickly and the weapon case was sealed to simplify storage. Like several mods of the MK15, the MK39 featured an impact-absorbing aluminum-honeycomb "false nose" forward of the warhead's "physics package." The "false nose" was tipped with a contact fuse consisting of two aluminum plates separated by an air space. The MK39 casing weighed 6,000 lbs.; fully-loaded bomb weight was between 9,000 and 10,000 lbs. The bomb centerbody measured 34.5" in diameter; the aft parachute section was 42" in diameter. Overall length was 11' 7"; the tail fins spanned 55". The bomb was built in two separate yields (Y1 and Y2)." *

*  Swords of Armageddon, Volume VI, Hansen


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