Little Boy

The Mk I "Little Boy" was 10 feet (3.0 m) in length, 28 inches (71 cm) in diameter and weighed 8,900 lb (4 000 kg). The design used the gun method to explosively force a hollow sub-critical mass of uranium-235 and a solid target spike together into a super-critical mass, initiating a nuclear chain reaction. This was accomplished by shooting one piece of the uranium onto the other by means of chemical explosives. It contained 64 kg of uranium, of which 0.7 kg underwent nuclear fission, and of this mass only 0.6 g was transformed into energy.

No full test of a gun-type nuclear weapon had occurred before the "Little Boy" device was dropped over Hiroshima. The only test explosion of a nuclear weapon had been of an implosion-type weapon using plutonium as its fissionable material, on July 16, 1945 at the Trinity test. There were several reasons for not testing the "Little Boy" device. Primarily, there was little uranium-235 compared with the relatively large amount of plutonium which, it was expected, could be produced by the Hanford reactors. Additionally, the weapon design was simple enough that it was only deemed necessary to do laboratory tests with the gun-type assembly (known during the war as "tickling the dragon's tail"). Unlike the implosion design, which required sophisticated coordination of shaped explosive charges, the gun-type design was considered almost certain to work.

Although occasionally used in later experimental devices, the design was only used once as a weapon because of the danger of accidental detonation. Little Boy's design was unsafe when compared to modern nuclear weapons, which incorporate safety features to endure various accident scenarios. The main objective of Little Boy was to create a weapon that was absolutely guaranteed to work. As a result, Little Boy incorporated only basic safety mechanisms.

 

 

 

 

 

Little Boy

 

Soon to be released from Masterpiece Models is this kit of the Little Boy atomic bomb.  The master for this kit was created in our shop by Matt Kilwein and  he has done an outstanding job in it's representation.  I was asked to build the kit and produce the instruction guide and then paint the model for the box art and and promotional materials.

The number of parts that make up this kit are relatively few.  The main component, the bomb, is a single piece of cast resin with excellent panel line and bolt details.  The attachment of  rear stabilizer fins provide the bulk of the construction efforts.  I made a quick template as a guide to help position the fins in the proper locations. 

Once the fins have been placed, the horizontal stabilizers rest on the edge of the fins; butt-joined to one another at the corners.  The last component are the small interior fins.  These fins can be scribed and then cracked to produce a hinge point which attaches to the horizontal stabilizer at the mid-way point.  The interior edges are positioned to the stabilizer fins 2mm from the bomb itself.

The remainder of the construction is very straightforward and can proceed quickly.  One must be somewhat mindful of the placement of the four forward antenna housings; a quick look at the reference materials and a little bolt counting is in order.  The location for the top housing is 2 bolts down from the mid-section panel line, while the lower housing is another 4 bolts below.  Small wings are attached along the circumference of the mid-section near the small vent holes.  The three fuses where detailed with small wire to replicate the fuse wire seen in period photographs.  Finally, a small cart is also provided in the kit.  Not only is this an attractive accessory, but it serves to provide a stable display platform for the bomb.

 

Painting and finishing the bomb presented an unique challenge for this armor guy.  Obviously the "normal" wear and tear would not be present.  My challenge, therefore, was to create an interesting presentation without relying on my usual bag of trick.  Also, I needed to keep in mind that the end presentation was to be used for box art and promotional materials, so once again restraint would be called for.

Using Tamiya acrylics thinned with lacquer thinner provided me with a nice, smooth surface.  I used a bit of shading and highlighting of the panels as we as to general shape as well.  Darker colors were sprayed to the lower areas to accentuate the roundness of the shape.  Taking a cue from the aircraft builders I added a dark preshade to the panel lines - a technique that I almost never do in my regular work.  The result, however, are quite attractive on surfaces such as this and really do bring out the details.  I sealed the base colors with a couple of light applications of Future floor polish to not only protect the paintwork, but to also provide a nice sheen to the surface.  Finally, I chose to do a little bit of work with the artist oils to further promote and enhance subtle color tones within the panels.

 

 

Final Pictures

 

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