return to missiles, nuclear warheads

RE: W-37 Nuclear Warhead
comments by Charles D. Carter

January 13, 2013

I have conducted a bit of research on the question and this is what I have found. I am interested in any addition or conflicting information.



  1. The W-31 warhead, developed by Las Alamos Nuclear Laboratory (LANL), was a multipurpose boosted fission warhead. The Nike Hercules used the W-31Y1 and W31Y2. The W-37, also developed by LANL, was intended as a high-yield multipurpose companion to the W-31. It was cancelled in September 1956 (See highlighted note below). The XW-37 (XW - Warhead in the development and test phase) was redesignated XW-31Y2 by where it was being tested.

  2. Four yield variants, of 2, 10, 20, and 30 kiloton yields, were deployed on these missiles starting in 1958 and finally retired in 1989. 2,550 of these models were produced. The 20 kt version of the W-31 was solely used in the Nike Hercules system. A similar variant, the XW-37, was a high yield version of the XW-31. Development started in January 1956. Three months later, the XW-31 was redesignated XW-31Y1 (for yield 1) and the XW-37 designation was changed to XW-31Y2 (for yield 2).

  3. W-31 Warhead Time Line:
  4. The W-31 warhead was deployed on the Nike-Hercules. Thousands of them were manufactured but very little has been published about them. This time-line has been developed from Chuck Hanson's material as well as other open sources.
    • Mid 1951 - Boosted, fission concept confirmed by IVY shot during GREENHOUSE series.
    • June 1952 - Project HEAVENBOUND study by Air Defense Command examines atomic weapons in the air defense role.
    • April 13, 1954 - AEC tells MLC that boosted air-defense weapons will be developed.
    • July 1953 - MLC settles on a 30" warhead for the NIKE-B to be operational in early 1957
    • December 1954 - Army asks AEC to develop the MK7 and a new 30" warhead for the NIKE-B.
    • January 1955 - DMA authorizes development of new 30" air-defense warhead
    • March 1955 - The Santa Fe Operations Office issued a scope-of-work covering the design of adaption kits for the XW-7 and the new 30" air-defense warheads.
    • March 1955 - Sandia and LASL suggest a higher yield air-defense warhead to increase the kill radius of the NIKE-B.
    • 23 March 1955 - Sandia conducts static load test on the XW-31 to determine the structural adequacy of the XW-31 and the Nike case sections. (Report)
    • April - 1955 - TEAPOT confirms the practicality of small, boosted warheads.
    • June 1955 - The Assistant Secretary of Defense requests a feasibility study on a high yield air-defense warhead.
    • Summer 1955 - Test program proposed safety tests on the XW-31.
    • August 1955 - The XW-31 is deleted from one-point safety tests because the design was still evolving.
    • August - 1955 - The DMA requests development of the new, high-yield weapon.
    • Mid September 1955 - Sandia and LASL present the formal design of the XW-31 with a lower yield than the weapon suggested in March.
    • November 1955 - A Sandia study report recommended that the XW-31 warhead replace the XW-7 warhead on the Air Force’s CROSSBOW missile.
    • January 1956 - The Department of Defense approves the high-yield program (XW-37) for the NIKE-B.
    • February 1956 - Both the XW-31 and XW-37 were scheduled to be operational by October, 1958.
    • Late February 1956 - A proof test of the XW-31 for the NIKE-B was scheduled for the Spring of 1957 at the NTS.
    • April 1956 - Development engineering begins on the high-yield warhead, XW-37, for the NIKE-B
    • 27 June 1956 - Sandia presents the ordnance characteristics of the XW-31/37 to the SWDB.
    • June 1956 - First flight tests of the XW-31 scheduled to begin. (Rescheduled for October)
    • June 1956 - The XW-31 or XW-37 warhead are proposed for the Air Force’s CROSSBOW anti-radiation missile.
    • September 1956 - The XW-37 is effectively cancelled when the XW-31 became the XW-31-Y1 and the XW-37 became designated the XW-31-Y2.
    • October 1956 - First flight tests of the XW-31 to begin after being rescheduled from June, 1956
    • 15 October 1956 - Sandia study on the use of parachute recovery of air-defense warheads to prevent plutonium contamination. (Report)
    • October 1956 - The proposed ordnance characteristics of the XW-31/NIKE-B were forwarded to the DMA.
    • November 1956 - The NIKE-B becomes the NIKE-HERCULES
    • February 1957 - A new version of the XW-31, the XW-31-Y3 is created.
    • March 1957 - Production engineering begins on the XW-31.
    • July 1 1957 - Operation PLUMBOB, shot Coulomb A, tests the one-point safety limits of the XW-31
    • September 6, 1957 - Operation PLUMBOB, shot Coulomb B, tests the one-point safety test of the XW-31
    • Mid September 1957 - Sandia released the design of the XW-31
    • May 1958 - The XW-31-Y3 was proof tested during the Holly shot of Operation HARDTACK at the PPG.
    • June 1958 - The adaption kit for the XW-31/NIKE-HERCULES design released.
    • June 1958 - First basic NIKE-HERCULES battery deployed.
    • 9 July 1958 - Report of Test Flight No. 7.8-24 XW-7/Nike Hercules Warhead Installation. Beacon failure at 3.8 seconds into flight. (Report)
    • October 1958 - The W-31 Mod 0 became operationally available.
    • March 1959 - Sandia proposed incorporation of handling-safety devices in W-31 warheads.
    • September 1959 - The MLC accepted Sandia’s suggested safety changes.
    • June 1962 - The design for the W-31 Mod 2 was released.
    • 4 November 1962 - Project Dominic I, Shot Fishbowl, W-31 detonated over Johnston Island. ( B Battery 2nd of the 52nd ADA)
    • March 1963 - Production of the W-31 Mod 2 began.
    • July 1967 - Retirement of the W-31 warheads began
    • June 1987 - Approximately 75 NIKE-HERCULES equipped with W-31 warheads remain in service in Europe.
Charles D. Carter
HM-69 Nike Site Historian
Everglades National Park
40001 State Road 9336
Homestead, Fl 33034