B41

B41 (Mk 41)

Aircraft bombUnited StatesThermonuclear (staged)

B41 — Photo: Wilson44691 · CC0 · background removed

Yield · TNT equivalent25 Mt

Key specs

Country: United States
Design: Thermonuclear (staged)
Type: Aircraft bomb
Weight: 4.84 t
Length: 3.76 m
Diameter: 1.32 m
In service: 1961–1976
Number built: 500

Overview

The most powerful nuclear weapon the United States ever deployed: a three-stage thermonuclear bomb of up to 25 Mt, carried by B-52 and B-47 bombers. At 4,840 kg it reached about 5.2 Mt per tonne, the highest yield-to-weight ratio of any weapon fielded in its time.

About 500 were produced between September 1960 and June 1962, in a 25 Mt "dirty" version and a 10 Mt "clean" one. It was the only three-stage weapon in US service and was replaced by the B53 between 1963 and 1976.

Effect radii: estimates

Calculated for 25 Mt

Fireball, maximum radius: ≈ 3.5 km
Initial radiation, 500 rem (5 Sv): ≈ 5.8 km
Blast 5 psi: most buildings collapse: ≈ 21 km
Thermal: third-degree burns: ≈ 43 km
Blast 1 psi: windows shatter: ≈ 64 km

Estimated ground ranges for an air burst at the optimum height over flat, open ground, computed from the yield with standard scaling laws. These are not measurements: real effects depend on the height of burst, terrain, buildings and weather.

Formulas from: Glasstone & Dolan, The Effects of Nuclear Weapons (1977), chapter II; Carey Sublette, Nuclear Weapons FAQ, section 5

Sources

Complete List of All U.S. Nuclear Weapons, Nuclear Weapon Archive (Carey Sublette)
B41 nuclear bomb, Wikipedia