B61

Aircraft bombUnited StatesThermonuclear (staged)

B61 — Photo: Wilson44691 · CC0 · background removed

Yield · TNT equivalent0.3–340 kt

Key specs

Country: United States
Design: Thermonuclear (staged)
Type: Aircraft bomb
Weight: 324 kg
Length: 3.6 m
Diameter: 340 mm
In service: 1968 – present
Number built: 3,155

Overview

The main US nuclear gravity bomb since the late 1960s and a "dial-a-yield" weapon: depending on the version, the yield is set between 0.3 and 340 kt before release. It can be dropped in free fall or by parachute, including laydown delivery that detonates after it reaches the ground, and is carried by fighter-bombers as well as heavy bombers.

Designed from 1963 and in full production from 1968, it has been built in more than a dozen modifications, about 3,155 bombs in all. The Mod 11 is a hardened earth penetrator; the Mod 12, produced from 2021, adds a guided tail kit and replaces several older versions. B61 bombs are also stored in Europe under NATO nuclear sharing.

Effect radii: estimates

Calculated for 340 kt

Fireball, maximum radius: ≈ 630 m
Initial radiation, 500 rem (5 Sv): ≈ 2.5 km
Blast 5 psi: most buildings collapse: ≈ 5 km
Thermal: third-degree burns: ≈ 7.3 km
Blast 1 psi: windows shatter: ≈ 15 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

Test footage

Archive films hosted on YouTube. Nothing loads from YouTube until you press play; the player then comes from youtube-nocookie.com.

Sandia National Labs · youtube.com

Sources

Complete List of All U.S. Nuclear Weapons, Nuclear Weapon Archive (Carey Sublette)
B61 nuclear bomb, Wikipedia