Home > Technology > Upshot-Knothole Grable: The Atomic Cannon Test

Upshot-Knothole Grable: The Atomic Cannon Test

This is archival footage of an old atomic test from 1953. The shell, designated a Mark 9 nuclear weapon, had a diameter of 280 mm (11.02 in), was 138 cm (54.4 in) long and weighed 364 kg (803 lb). The yield of the test, at 15 kt, was almost identical to that produced by the ‘Thin Boy‘ bomb used on Hiroshima in 1945, though it was significantly lighter and more compact that the 1945-era bomb.

Interestingly the firing mechanism of the device (gun-type assembly) and fuel (Uranium-235) were similar to the ‘Thin boy‘ device. The vast majority of nukes developed and tested since WW2 use some version of an implosion-assembly powered by Plutonium-239. Now I don’t know whether the device was a practical weapon but this short film of the test is worth watching anyway.

Enjoy! Comments?

Categories: Technology
  1. Rum
    May 7, 2012 at 4:25 pm

    The story goes that the Chinese became much more willing to negotiate an end to the Korean War when small, accurately deliverable nukes entered the US inventory. They were considered use-able at the time, in other words.
    If you watch the films of American bomb testing, many of them show soldiers getting out of trenches and trying to manuver soon after the blast. That was to learn what the parameters of safety were in a nuclear explosion environment. Or at least to make the commies think we were.
    As you probably know, plutonium is about 1,000 times easier to make than U235 and has a much smaller critical mass with an implosion trigger.

  2. Matt Strictland
    May 8, 2012 at 10:19 am

    Thanks. That was neat. I guess there is no kill like overkill.

  3. hoipolloi
    May 9, 2012 at 3:50 pm

    The nuclear cannon looks neat. I understand it blew 5 miles away from the firing base. How far away the observers and the guys who loaded the gun were when it was triggered? Why was it not used in Vietnam? Or why don’t they use it in Afpak?

    Becaues we would rather have drama, theatrics with drones, suicide bombers etc., than a decisive solution?

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