Thin Man (nuclear bomb) and the name came from the Dashiell Hammett detective novel "The Thin Man" and series of movies by the same name. The "Fat Man" bomb would be round and fat and was named after Sydney Greenstreet's character in "The Maltese Falcon". "Little Boy" would come last and be named only to contrast to the "Thin Man" bomb. Oppenheimer assembled a team at the Los Alamos Laboratory to work on plutonium gun design that included senior engineer Edwin McMillan and senior physicists Charles Critchfield and Joseph Hirschfelder. Critchfield had been working with sabots, which Oppenheimer believed would be required by the
Thin Man (nuclear bomb) need to be accelerated to a speed of at least —or else the fission reaction would begin before the assembly was complete, blowing the device apart prematurely. Thin Man was long, with wide tail and nose assemblies, and a midsection. The length was necessary for the plutonium "bullet" to pick up adequate speed before reaching the "target". Weight was around for the final weapon model. There were no aircraft in the Allied inventory that could carry a Thin Man without being modified. However, the American Boeing B-29 Superfortress could be modified to carry it by removing part of the bulkhead