The W86 was an American earth-penetrating ("bunker buster") nuclear warhead, intended for use on the Pershing II intermediate-range ballistic missile (IRBM). The W86 design was canceled in September 1980 when the Pershing II missile mission shifted from destroying hardened targets to targeting soft targets at greater range. The W85 warhead, which had been developed in parallel with the W86, was used for all production Pershing II missiles. Development work for the W86's penetrator case began in 1975 at Sandia National Laboratories. The weapon was intended to allow for the destruction of hardened structures and the cratering of runways while using smaller yields.

Design

The warhead was developed from Los Alamos nuclear artillery shell technologies. A 2005 study by the National Research Council that examined a number of nuclear earth penetrating weapon proposals, described the W86 as being 170 mm in diameter and weighing 184 kg. The study calculated that such an EPW could penetrate 7.2 m into medium strength rock, 18.7 m into low strength rock and 115 m into silt or clay, assuming a peak allowable deceleration of 10000 g-force. The study cites the classified Sandia development report for the W86 warhead for its figures. In the National Research Council study, they refer to the "low-yield weapon" (W86) as having a yield of less than 5 ktTNT or less than 10 ktTNT. A 1979 article in Sandia's monthly Lab News magazine describes a 400 lb test unit penetrating 67.5 ft into the Tonopah Test Range lake bed, striking the ground at 1796 ft/second. Development called for approximately 20 tests of the penetrator into various mediums. The weapon was an implosion-type weapon.

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