The Mark 27 Thermonuclear Bomb was the largest yield free fall nuclear bomb ever deployed by the USN. Designed as a replacement for the Mark 15 nuclear bomb, the weapon was designed to be carried A-3 Skywarrior & A-5 Vigilante. The bomb was first deployed in 1958 and was intended to arm the Regulus II cruise missile until the program was canceled in the same year. When JFK became president in 1960, the Navy lost much of its funding for a nuclear bomber force to ICBM development and the A-3 & A-5's were re-tasked to other missions. By 1964 the Mark 27 was retired from service leaving only the B-43 as the only megaton class nuclear weapon in the USN inventory.
The Mark 27 was not designed with a parachute system like many other weapons of the period. It could be delivered using the Low Altitude Bombing System (LABS), which entailed a aircraft flying fast & low until nearing the target in which the aircraft climbed rapidly and at predetermined angle would release the weapon. The bomb then would along fly a ballistic trajectory to the target allowing the dropping aircraft time to leave the area. In addition this bombing method allowed pilots to drop their weapons over hills and mountains without actually seeing their targets adding protection from the blast and from air defenses.
Dimensions
L: 11ft, 9.5 in
D: 2ft, 6.2 in
W: 3,150lbs
Yield: Top Secret (Believed to be 2+ Megatons)