Posted on 06/08/2015 2:17:41 PM PDT by StormPrepper
Post-war[edit]
When the war ended, it was not expected that the inefficient Little Boy design would ever again be required, and many plans and diagrams were destroyed. However, by mid-1946 the Hanford Site reactors were suffering badly from the Wigner effect. Faced with the prospect of no more plutonium for new cores and no more polonium for the initiators for the cores that had already been produced, Groves ordered that a number of Little Boys be prepared as an interim measure until a cure could be found. No Little Boy assemblies were available, and no comprehensive set of diagrams of the Little Boy could be found, although there were drawings of the various components, and stocks of spare parts.[62][63]
At Sandia Base, three Army officers, Captains Albert Bethel, Richard Meyer and Bobbie Griffin attempted to re-create the Little Boy. They were supervised by Harlow W. Russ, an expert on Little Boy who served with Project Alberta on Tinian, and was now leader of the Z-11 Group of the Los Alamos Laboratory’s Z Division at Sandia. Gradually, they managed to locate the correct drawings and parts, and figured out how they went together. Eventually, they built six Little Boy assemblies. While the casings, barrels and components were tested, no enriched uranium was supplied for the bombs. By early 1947, the problems caused by the Wigner effect was on its way to solution, and the three officers were reassigned.[62][63]
The Navy Bureau of Ordnance built 25 Little Boy assemblies in 1947 for use by the nuclear-capable Lockheed P2V Neptune aircraft carrier aircraft. Components were produced by the Naval Ordnance Plants in Pocatello, Idaho, and Louisville, Kentucky. Enough fissionable material was available by 1948 to build ten projectiles and targets, although there were only enough initiators for six.[64] All the Little Boy units were withdrawn from service by the end of January 1951.[65]
http://en.wikipedia.org/wiki/Little_Boy
Although Little Boy exploded with the energy equivalent of 16,000 tons of TNT, the Strategic Bombing Survey estimated that the same blast and fire effect could have been caused by only 2,100 tons of conventional bombs: “220 B-29s carrying 1,200 tons of incendiary bombs, 400 tons of high-explosive bombs, and 500 tons of anti-personnel fragmentation bombs.”[61] Since the target was spread across a two-dimensional plane, the vertical component of a single spherical nuclear explosion was largely wasted. A cluster bomb pattern of smaller explosions would have been a more energy-efficient match to the target.[61]
http://en.wikipedia.org/wiki/Little_Boy
In the book one city was on the primary target list. It was clouded over so they chose Hiroshima as their second choice. I had walked all around the A-bomb building and also stood at ground zero, actually picked up some dirt from that. My hotel was just down the river from there about a quarter mile away. I saw the granite posts that were at the entrance to the Ai bridge which was the target. I saw the spalling of the granite. There is a museum you can visit which is very interesting and provocative and haunting.
Hiroshima was the primary for the first mission.
Kokura was the primary for the second mission, was clouded over so the crew went for the secondary (Nagasaki). But that was clouded over as well, and it was only a fortuitous break in the clouds that allowed the weapon to be dropped. And it detonated WAY off target.
That second mission was the definition of “harrowing”. Jinxed almost from the start to the point where Bockscar’s engines started dying of fuel starvation taxiing out from a diverted landing on Okinawa.
“We had a total of three nukes, all different designs. The first one we set off to test. Until we did, we had no idea whether or not any would work. The next two we dropped on Japan. We dropped the second nuke on Japan a week after the first because they refused to surrender after we dropped the first one.”
Trinity (16 July) was an implosion bomb as was the Nagasaki bomb (9 Aug). The Hiroshima bomb (6 Aug) was a gun-type bomb. There was very little doubt that the gun-type bomb would go boom. Therefore, there was no need to test that type prior to it’s operational use. The implosion bombs were much more complicated and there was enough doubt that they would work that we decided it was necessary to test an implosion bomb at Trinity before it was operationally deployed at Nagasaki.
Thats one reason why under various nuclear warplans (like SIOP) there were so many bombs targeted on specific cities. Create overlapping blast patterns with a bunch of smaller bombs.
The Sovs couldn’t target as well as we could, so they went the one big bomb route.
(aside: another reason we went that way was the mathematical probabilities of achieving mission success. Getting really close to 100% requires more than one or two bombs.)
Trinity wasn’t a “bomb”, it was a “device”. It never could have been configured for use in combat, except maybe by loading it onto a ship for detonation in a port. But certainly not by dropping out of an aircraft.
I was being fitted for the invasion of Japan when the first bomb was dropped. At the time I think my thoughts were that we just had a big bomb. When it was announced we had dropped a second bomb the situation looked very good for our side. When the Jap big wigs offered to surrender we had realization the fighting was over and the Japs knew it.
It’s all in the book. But yeah, interesting read. I was also at the Imperial Palace in Tokyo. From there I could look out to see where all the devastation happened all those years ago. Sixteen square miles were wiped out.
The exact numbers are classified, but I do not believe that any thermonuclear weapon actually used in a production warhead has ever exceeded about 30% of its yield from fusion.
Keep in mind also that the plan, should the Japanese still not surrender after Nagasaki, was to scrap the existing target list and drop the third bomb (components were enroute to Tinian) somewhere in the Tokyo area, within clear sight of the Imperial Palace. But not close enough to do damage.
Didn’t read about that. Secretary Simpson was adamant about not dropping the bomb on historic sites.
Yes, thats true. Again, the Imperial Palace wasn’t going to be targeted ... just somewhere close enough (Yokosuka?) where the Japanese Government would be able to clearly understand where the Americans were prepared to put the fourth bomb.
And given the problems with the Nagasaki mission, Tibbits was going to command the third mission himself.
I lived in Tokyo for several months. Did a lot of traveling around the country.
My understanding is that lithium in the second stage indirectly created the fast neutrons which fizzled the U-238 tamper unexpectedly. 80-90 percent of the yield was due to fission and this is why Castle Bravo was so dirty.
The net effect is that with the relative abundance of 7Li in the dry fuel, twice as much fusion energy was produced, and about three times as many neutrons bombarded the tamper than were expected, which gave rise to a much greater, and much dirtier fission yield from the tamper.
You have a point; I don’t know. I only repeat what I’ve read from others, which they may have done themselves.
Remember that Bohr himself was living in Nazi occupied territory [which was why Heisenberg was able to travel to, and meet with him.] Bohr and Heisenberg were close. I think Bohr would have interpreted, and possibly remembered, any remarks Heisenberg made sympathetically ex post facto. But I don't know that there are any records of what was said before Heisenberg was taken into custody by the British.
Wow. You are really smart. Can you explain what you wrote as if I’m a 5 year old?
I’m 57 and I have an IQ of 144 and I still don’t understand what you said. Thanks.
He said big bomb go boom boom boom instead of boom. Too much blast in the A blast?
I think??
Remember the Iowa explosion where they packed that OLD powder left over from W W Eye Eye too tight? Again, to much boom for the blast.
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