B41 nuclear bomb

The B-41 (also known as Mk-41) was a thermonuclear weapon deployed by the United States Strategic Air Command in the early 1960s.

It was the most powerful nuclear bomb ever developed by the United States, with a maximum yield of 25 megatons of TNT (100 petajoules).

The B-41 was the only three-stage thermonuclear weapon fielded by the U.S.[1] In June 1955, the US Department of Defense requested a feasibility study for a Class B (over 10,000 lb or 4,500 kg weight) bomb and warhead.

[6] By March 1957, it was decided to place equal emphasis on the clean and dirty versions of the weapon.

These tests showed that there was sufficient time between contact and the firing signal being sent for the fuze design to work correctly.

[11] In June 1958, the requirement to be able to select air and ground burst fuzing modes from the cockpit was canceled.

Another proposal was to delay the program and include a full-fuzing (FUFO) capability into the weapon that would allow for laydown delivery.

[13] In November 1958 it was decided that the weapon would always be deployed in the parachute retarded condition, and thus an option selector switch was no longer needed.

In December, Sandia raised issues with the safety of the weapon and proposed additional safing devices.

[18] The weapon did not have a laydown fuzing capability as the design of the physics package did not make that possible without extensive redesign and further nuclear testing.

[verification needed][19][1] In November 1956, development of the W41, a warhead version of the B41, began at Lawrence Livermore National Laboratory.