Project Y: the Los Alamos Story - Edith C. Truslow, Ralph Carlisle Smith
Edith C. Truslow, Ralph Carlisle Smith - Project Y: the Los Alamos Story, pp.343-344.
Testing Program
Two weapons existed in August 1945: the "Little Boy" U-235 gun assembly and the "Fat Man" plutonium implosion assembly. The Little Boy program was discontinued, however, because the weapon had low efficiency relative to the amount of active material involved.
The Fat Man presented other difficulties. Its absolute degree of reliability was so unknown that the safety factor in each component was unknown, and all that had been proved in tests was that there had been no failure. The next drop, however, could never be predicted with confidence. Also, the weapon's mechanical, electrical, and nuclear complexity required men with the highest degree of training, responsibility and experience for field experiments.
To get reliable statistical data on the performance of each component required devising some system whereby actual conditions experienced by the bomb in flight could be duplicated in the laboratory. Telemetering of flight information from the falling bomb was undertaken. Roll, pitch, yaw, vibration frequency, temperature, and pressure were recorded.
It was believed that once the conditions experienced by a bomb in flight were known, they could be duplicated in a test laboratory and made severe as desired. The behavior of each weapon component could then be tested and its point of failure ascertained. The weak points would then be strengthened and a safety factor for the weapon, as a whole, would be established.
Designing program
After the war, the Laboratory, without concrete guides from higher authority, faced the necessity of holding together its highly experienced group of design and development technicians. The Fat Man, as it was used at Nagasaki, could hardly be called anything more than a scientific gadget; it was certainly not a weapon. Its assembly and use demanded the most experienced technical personnel in large numbers, which is certainly incompatible with modern warfare. It was decided that the Ordnance Engineering Division would re-engineer the weapon to make production easier, simplify the assembly at an advanced base, and minimize the number of highly trained assembly personnel required. With this as primary objective, it was decided to do whatever was possible to improve the ballistics of the bomb, subject to the dimensional restrictions imposed by the dimensions of the B-29 bomb bay.
Testing Program
Two weapons existed in August 1945: the "Little Boy" U-235 gun assembly and the "Fat Man" plutonium implosion assembly. The Little Boy program was discontinued, however, because the weapon had low efficiency relative to the amount of active material involved.
The Fat Man presented other difficulties. Its absolute degree of reliability was so unknown that the safety factor in each component was unknown, and all that had been proved in tests was that there had been no failure. The next drop, however, could never be predicted with confidence. Also, the weapon's mechanical, electrical, and nuclear complexity required men with the highest degree of training, responsibility and experience for field experiments.
To get reliable statistical data on the performance of each component required devising some system whereby actual conditions experienced by the bomb in flight could be duplicated in the laboratory. Telemetering of flight information from the falling bomb was undertaken. Roll, pitch, yaw, vibration frequency, temperature, and pressure were recorded.
It was believed that once the conditions experienced by a bomb in flight were known, they could be duplicated in a test laboratory and made severe as desired. The behavior of each weapon component could then be tested and its point of failure ascertained. The weak points would then be strengthened and a safety factor for the weapon, as a whole, would be established.
Designing program
After the war, the Laboratory, without concrete guides from higher authority, faced the necessity of holding together its highly experienced group of design and development technicians. The Fat Man, as it was used at Nagasaki, could hardly be called anything more than a scientific gadget; it was certainly not a weapon. Its assembly and use demanded the most experienced technical personnel in large numbers, which is certainly incompatible with modern warfare. It was decided that the Ordnance Engineering Division would re-engineer the weapon to make production easier, simplify the assembly at an advanced base, and minimize the number of highly trained assembly personnel required. With this as primary objective, it was decided to do whatever was possible to improve the ballistics of the bomb, subject to the dimensional restrictions imposed by the dimensions of the B-29 bomb bay.