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Atom bomb little boy. World war 2 hiroshima bomb

17 Apr
2012

Atom bomb little boy. World war 2 hiroshima bomb,hasegawa models

Neil and John build and write about Fujimi’s 1/144 B-29 as Enola Gay and Kora’s 1/48 kit of Little Boy – the world’s first atomic bomb

The dual subject matter of this build represents quite a departure from my usual biplanes. It all came about because my son John is into physics and had been studying the Manhattan Project. I find history fascinating and some of what John told me was truly amazing. It is the personalities which really interest me, and in this case it was the Nobel Prize winning Richard Feynman.

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Perhaps best known for his part in the Rogers Commission enquiry into the Challenger disaster, Feynman was at Los Alamos as a young man. His autobiography, Surely You’re Joking Mr. Feynman? sheds a light on those years, which I find packed with irresistible humour. For me, the logical working out of all this was a model project. The obvious choice was the end product in the form of Little Boy, and the means of delivery, the B-29 Enola Gay.

Scaling Down

One thing was certain, there was no way that my limited display or storage space was going to accommodate a B-29 at 1/72, much less anything above. It had to be 1/144. In my usual impetuous rush to get started on a new project, I set off for my local model shop and it wasn’t long before I had Enola Gay at the desired scale, in my hot little hands. Unfortunately, the version I had purchased turned out to be one of those much-reissued kits from another age, which should have been retired long ago, and soon I was struggling with flash, warped parts and poor fit whilst knowing that lack of detail and raised panel lines were going to limit what I could achieve anyway.
It was at this point that I confided my troubles to our Editor and the project turned a corner. The version that he recommended was the Fujimi kit. Indeed, he did better than that and sent me one. Oh well, at least I had Enola Gay decals.
My experience of Fujimi kits is limited to one of their 1/72 Vought Cutlass range and I was very impressed. The only reason I have not been back for more is that they don’t tend to go in for Harts, Siskins or Bulldogs (pity). The question was, are they as good at 1/144? The answer is a resounding ‘Yes.’ Beautifully engineered for excellent fit, just the right level of detail and nicely engraved panel lines gave me everything I wanted.

Building Enola Gay

Both B-29 kits began with painting the forward fuselage interior. This was a pretty simple process of olive drab with black for seats, consuls and control yokes. A quick dry brushing completed the job. With my original purchase, the need to loose some gun turret and U238 in a variety of ways and, like Uranium, Plutonium could be induced into a nuclear chain reaction.

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At this early stage, Plutonium was only being produced in very small quantities in laboratory conditions, and even less was known about its nuclear characteristics than Uranium, but it seemed much more suitable for use in an explosive device, both because it could be artificially manufactured and because it underwent a more rapid fission reaction, potentially releasing more energy. It was agreed, then, that initial research would be focused on producing a Plutonium bomb, with Uranium research continuing as a backup.

Several possibilities were discussed, but the gun method was selected as most suitable for immediate development. This simple technique entails the separation of the fissile material into two stable components: the target, fixed at the end of a barrel, and a projectile at the ‘breech’ end. 

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Fuselage halves joined and forward bomb bay packed with Wing halves joined. Stout stubs give a good positive fixing With wings and tail added, the main airframe is ready for as much weight as possible painting

The projectile is porthole positions, plus poor joins, soon had me bogged down in a mass of filler. The Fujimi kit has infill pieces for the necessary holes and a dab of correction fluid soon sorts out any minor discrepancies. Both kits acknowledge that left to its own devices this model is going to be a tail-sitter and provide tail support props as one solution. Once the fuselage halves were joined, I packed the forward bomb bay with as much weight as possible before closing the doors. This did the trick.

Next, the wing halves were joined. The Fujimi kit has stout spar stubs, which give a good positive fixing and set the dihedral without any fuss. With the main airframe assembled, it was time for some painting. For the overall silver finish I brush painted with Humbrol Metal Cote 27002 Polished Aluminium.
The process began with an initial coat of Metal Cote. When thoroughly dry, this was sealed with a coat of Johnson’s Klear, since you can’t overpaint Metal Cote without it lifting. 

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A Preiser figure adds a sense of scale

Small components were painted before fixing

A second coat of aluminium followed and when completely dry, this was lightly rubbed down with 1500 grit wet & dry, and when the model was thoroughly dry it was buffed with a paper tissue. The cellulose fibres in the tissue are just enough to do the polishing. Panels across the shoulder of the wings were masked and painted a greyer shade of aluminium (Metal Cote plus a little matt white) in accordance with photographs obtained from the Internet. 

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Some weathering around the engine nacelles and exhausts was done with graphite powder and the whole sealed with another coat of Klear. Finally, the panel lines were slightly emphasised with a well-thinned acrylic wash. The final painting job included all the small parts such as engine fronts, propellers and undercarriage parts. I was then ready for final assembly. Once the model was together, decals were applied and the complex framing of the B-29’s transparent nose was done with thin strips of silver decal. I made this by painting Metal Cote onto Xtradecal clear sheet. This ensured a shade match with the main fuselage.
Fujimi had provided me with a very nice replica of Enola Gay basking in the Pacific sunshine.

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.. Scaling Up Again – Building Little Boy

I decided to represent the worlds’ first atomic bomb with the 1/48 resin kit by Kora. I could have chosen their 1/72 version but somehow I wanted to get in closer.
The transporter trolley and main body of the bomb are cast in resin and a complex etched fret completes the package. Whilst obviously from good quality masters, the resin components do indicate that this kit has some mileage on the clock. There are casting blocks and flash to remove and surface air bubbles need to be dealt with. My favoured material for doing this is Milliput superfine white.

For some time, I was one of those modellers for whom an etched part was as likely to end up superglued to my thumb as attached to the model. To do myself justice, as this medium has become more widespread, I have improved. I can now usually fix a two-dimensional etched part to a model surface without too much trouble. Forming three-dimensional structures is still another matter. The cross between origami and watchmaking which is required to make up the tail unit of Little Boy caused me to go a very funny colour and mutter dark threats.

Despite the instructions being of no use at all at this point, I got there in the end. My photographs of the build at this point seem to have evaporated in cyber space. Perhaps just as well.

I painted the trolley Humbrol US Gull Grey (129). The wheels lend themselves to weathering and come up very nicely. The bomb itself was a bright blue and I used Humbrol French Blue (14). After the tail, the remainder of the etched parts are for external sensors and fuses. Even quite recent photographs had these airbrushed out for security reasons.

A Sense of Scale

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Enola Gay sits in the Pacific sunshine awaiting her call to duty

I used a figure from the excellent Preiser range (USAAF Pilots & Ground Crew #67003) to give a sense of scale to my model of Little Boy. Posing Enola Gay in the background and using the camera angle to create perspective, I had all the elements to portray that fateful day in 1945 when the Manhattan Project reached its culmination.

Entering Enola Gay or Little Boy into an Internet search engine gave me all the references I needed. Enola Gay is preserved in the Smithsonian collection (See SAMI Vol. 14 Issue 2 p. 176-177)

Little Boy bomb facts

Since 1939, with the outbreak of war, developments in the field of atomic physics became of grave concern to several of the world’s leading physicists, particularly the Hungarian Leo Szilard. With war spreading through Europe, fear grew about the development of nuclear technology. Szilard impressed his fears on Albert Einstein, who knew better than anyone the vast destructive potential of atomic power, and so he and Szilard co-authored a now infamous letter to President Roosevelt, communicating the fear of the possibility of ‘extremely powerful bombs of a new type’ which could be constructed by hostile countries. Einstein’s opinion was enough to prompt Roosevelt to create a Uranium Research Committee; a research effort which ultimately evolved into the full scale military research project, under the directorship of General Leslie R. Groves and scientific leadership of Dr. J. Robert Oppenheimer, which became known as the ‘Manhattan Engineer District’ or simply ‘Manhattan Project.’

In February 1941, Plutonium had been discovered: It was found that Plutonium could be synthesised from fired against the target so that the two come together and fuse as rapidly as possible. Accompanying the assembly is a combined ‘tamper’ and neutron reflector; a material that will surround the assembled core, designed to reflect radiating neutrons back into the core, further promoting the reaction and delaying the core from blowing itself apart. This method was selected both for its simplicity and reliability.

Oppenheimer reasoned that, compared to the Plutonium device, a Uranium gun device would be Robert Oppenheimer straightforward to adapt. The strategy was, then, to develop a Plutonium gun and then derive a Uranium gun. He personally assumed responsibility for the early development of the gun design, and with mathematical physicist Charles Critchfield and engineer Edwin Rose proposed a design capable of delivery by heavy bomber.
Work continued on the Plutonium gun, until July 1944, when the first batch of reactor-bred Plutonium was delivered. It was quickly realised that it differed 
from the Plutonium previously analysed in one important aspect – it was contaminated with an isotope of Plutonium (Pu240) that was very unstable. This meant that it fissioned much more readily than had been anticipated, and could not be used in a gun device.

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Further refinement of the Plutonium was impractical, and so the gun plan was abandoned in favour of an alternative technique which had also been discussed at Berkeley; an implosion device, where an array of carefully arranged explosive charges would implode segments of Plutonium very rapidly into a small core. The implosion technique would be much more effective than the gun, albeit significantly more complicated, and development had already begun on the ‘Fat Man’ device – the bulbous spherical gadget contrasting the long, thin gun design.
By February 1945, the specification for ‘model 1850’ was complete, code named
Little Boy. Little Boy would not be tested before use; there simply wasn’t enough U235 to spare, and the design was virtually guaranteed to work. In fact, the design was almost too effective, bordering on outright dangerous. The designers knew that any one of a series of accidents could precipitate a nuclear incident. A large concern was the cordite detonation mechanism. Fire, lightning strike, or ditching in water could potentially cause unintentional firing of the charge, leading to full scale nuclear detonation. Even if the carrying aircraft ditched safely in the ocean, and seawater did not trigger the detonator, salt water could act as a moderator, and induce a ‘fizzle.’

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General Leslie Groves (left) was appointed the military head of the Manhattan Project

As of May 1945, the device was ready for manufacture, but the Uranium to fuel it was not. Despite continuous work at the main Uranium production site at Oak Ridge, Tennessee over the previous two years, there was still not enough U235 for one bomb. By July 14th, the main research establishment at Los Alamos, New Mexico, had completed assembly of several Little Boy cases, as well as one Uranium projectile, enriched to an average 80% purity. On the 16th, at the same time as the Fat Man gadget produced the world’s first nuclear explosion at the Trinity test site, the components were loaded onto the USS Indianapolis, a heavy cruiser bound for Tinian island.
By the 26th, the units had been safely delivered, and the target assembly completed and dispatched by air.
By August 1st 1945, all the parts had been fitted into a case, with the exception of the cordite charge, which weapon officer Captain William Sterling Parsons wisely elected to load in-flight.
Parsons armed the bomb by hand, at 31,000 feet, and it was released over Hiroshima at approximately 8:15 am local time, immediately killing around 70,000 people.

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