Talk:Gun-type fission weapon

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[edit] Plutonium gun

Does Plutonium really rule out the gun method alltogether or does it just mean the gun would have to be prohibitively long (extra length giving it extra time to gain more speed)? I recall reading somewhere that the reason that the Plutonium gun program was abandoned during the Manhattan Project was because the bomb would have to be so long that it would require both bomb bays on the B29 to open at the same time, which was technically very difficult to accomplish. I know a plutonium bomb would be inefficient, but would it be impossible? --Fastfission 15:01, 20 January 2006 (UTC)

I believe plutonium totally ruled out the gun method although I am not sure of this. The main problem with the thin man concept wasnt with the bomb bays opening at the same time. The B-29 could open both fairly quickly and wasnt much of a problem at all. The problem with thin man was that it was shackled at two locations. Getting these two shackles to release simultaneously was difficult and plenty of testing went towards this problem. The simultaneous release was never worked out and the USAAF settled on using a British designed single shackle (Type F I believe) that closely resembled the single point shackle used to drop Tall Boys and Grand Slams from the Lancaster.

It is not impossible for Pu-239 or U-233 to be used in a gun-type weapon. However, production of these isotopes yields impurities (Pu-240 and U-232) which would require an extremely high gun-tube velocity. This would itself require either impractical explosive design, high-strength tube design, and/or an impractically-long gun-tube. Plus, there is the issue of pre-detonation (again, the gun-tube velocity issue) which would make the weapon very inefficient. The impurities are much less of an issue in a sphere-design weapon. But, since Pu-239 and U-233 production is fundamentally easier than U-235 production, and since gun-type bombs are fundamentally easy to build, some parties might be willing to go this route despite the inefficiencies involved. 147.145.40.44 23:32, 30 November 2006 (UTC)

I wonder what the critical lengths and velocities for tube weapons are for the various isotopes are. We can probably guess what it is for U-235 from historical photographs. 147.145.40.44 23:32, 30 November 2006 (UTC)