An illustrated guide to the Atomic Bombs
By Ryan
Crierie

NOTES: A large number of these photos were assembled from the RG-77-BT
collection in the Still Photo collection of the National Archives II building in
College Park, MD.

Early Bombs

“Thin Man” Plutonium Gun Type Bomb Casings in 1944. In the
background you can see “Fat Man” casings. It is unknown whether they are the
early Model 1222 “Fat Man” casings, which required 1,200 bolts to assemble, or
the later Model 1561 casings which were substantially easier to assemble and
which were used for the production versions.

Initial Bomb Assembly and Test

Photograph of personnel checking a casing. A significant
number of extra casings were shipped to Tinian and used in various tests with
“dummy” bombs which contained all the active components of a working atomic
bomb, but no fissile material to test out and prove the assembly procedures for
the actual devices themselves.

Implosion Sphere for Fat Man nearly assembled and about to be
placed inside it's casing.

Photograph from LANL History website showing partially
shrouded Little Boy unit designated L-1. This unit was assembled with
non-nuclear components and dropped on 23 July 1945. Test was a complete
success.

Little Boy unit checked up to a bank of equipment; possibly to
test/charge components within the device. Unknown whether this is a test unit or
L-11; the unit dropped on Hiroshima.

Project A (Alberta) member CDR A. Francis Birch (left) numbers
Little Boy Unit L-11 while Norman Ramsey (right) watches. This is the actual
unit which was dropped on Nagasaki.

Final Bomb Assembly

Fat Man devices after they were assembled, underwent a final procedure
outside the Assembly Building, where their crevices were filled with putty, and
then oversprayed with sealant to maintain the proper environment within the
device during the time it would take to deliver it to the target.

In this photograph, you can see the putty being applied to the
forward polar plate.

The sealant is now being applied via spray gun.

Workers have substantially completed application of the
sealant. Note the writing on the tail fin assembly and the logo on the bomb's
polar plate and on the worker's coveralls.

This is a frame taken from a color movie taken of the sealant
application, showing the color of the device and sealant/putty.

Once the device was virtually complete, workers began to sign
their names and various exhortations onto the device.

Close up of names on tail assembly of Fat Man.

“A Second Kiss for Hirohito!” signed by Rear Admiral W.R.
Purnell, USN on the side of Fat Man.

The completed Fat Man device is being lowered/checked over on
it's transport dolly for the trip to the airfield.

Bomb Loading

The completed bomb was then towed towards the airfield under
cover with an escort.

It's destination? One of two bomb pits constructed on
Tinian.

Pit Number One Today. This pit was used to load Little Boy
onto the Enola Gay. Identification was accomplished by historians from
studying photographs of the bomb loading sequences and comparing the bolt holes
in the photographs to the pits today.

Pit Number Two today. It was used to load Fat Man onto
Bocks' Car.

Preliminary pit alignment was proceeded with.

The Bomb and it's dolley were then manually pushed towards the
pit.

The device's alignment was checked over by eye and
hand.

The towing cable was then disconnected from the dolley as MPs
kept watch.

The device was then raised up on a hydraulic lift and the
metal gutters which guided it over the pit were removed.

Once it was aligned with the pit, the device was then lowered
down.

Device almost lowered to the bottom of the pit.

Device now fully seated in the pit. Still covered with tarp
for security reasons.

The aircraft that will carry the device is then backed up
slowly over the pit.

Alignment of the device with the aircraft's bomb bay proceeded
with a lot of 'hands on' from fairly high ranking personnel.

Once the device was aligned up, the security/protective shroud
was removed in anticipation of loading.

This is Unit L-11; the actual “Little Boy” bomb being (or
about to be) loaded into the Enola Gay.

Hydraulic lift has raised the device about halfway into the
bomb bay.

The device is nearly there...

View from within the pit showing the dolley frame and the
fully extended hydraulic lift.

The device is now in the bomb bay and is in the process of
being attached to the sway brackets that will secure it to the aircraft.

A different view of the device in the
bay.