Tsar Bomba (RDS-220 hydrogen bomb) – 50Mt
The RDS-220 hydrogen bomb, also known as the Tsar Bomba, is the biggest and most powerful thermo nuclear bomb ever made. It was exploded by the Soviet Union on 30 October 1961 over Novaya Zemlya Island in the Russian Arctic Sea.
The hydrogen bomb was air dropped by a Tu-95 bomber using huge fall-retardation parachute. The detonation occurred 4km above the ground producing a yield of 50Mt, which is believed to be equivalent to the explosive power from the simultaneous detonation of 3,800 Hiroshima bombs.
Tsar Bomba contained three stages, unlike normal thermonuclear weapons that explode in just two stages. While the addition of third stage increased the explosive power of the thermonuclear, the bomb’s actual yield of 100Mt was reduced by 50% to limit radioactive dust.
B41 nuclear bomb – 25Mt
The B41 or Mk-41 with a yield of 25Mt is the most powerful thermonuclear weapon ever fielded by the United States. About 500 bombs were produced between 1960 and 1962, remaining in service, until July 1976.
The development of Mk-41 commenced in 1955 to fulfil the US Air Force’s requirements for a Class B (10,000lb), high yield thermonuclear weapon. The prototypes were test fired during Operation Hardtack Phase I in 1958.
The three-stage thermonuclear weapon was primarily boosted by deuterium-tritium and believed to have used Lithium-6 (95% enrichment) deuteride fuel for fusion stages. Two versions were produced, a “clean” version (lead encased third stage) and “dirty” (uranium encased) version, both were air dropped by attaching with two parachutes for delayed detonation.