Conventional — penetrating · United Kingdom · 1945
Grand Slam
Grand Slam (22,000 lb bomb)
The largest conventional bomb of World War II, an enlarged version of the Tallboy.
See Grand Slam in the 3D simulator- TNT equivalent
- 5.5 tPublic estimate
- Energy
- 23 GJ
- Mass
- 10 tDocumented
- Explosive charge
- 4.2 tDocumented
- Dimensions
- 7.8 m · Ø 0.94 mDocumented
- Type
- Penetrating “earthquake” bomb
- Period
- World War II
- Status
- Historical
Grand Slam releases about 2,700 times less energy than Little Boy (Hiroshima, 1945).
Key points
- Dropped by Lancaster B.Mk I “Specials”, stripped of their turrets to carry the load.
History
On 14 March 1945, a single Grand Slam brought down part of the Bielefeld viaduct, which dozens of raids had failed to cut for good.
- 1943 Designed by Barnes Wallis.
- 14 March 1945 First use: Bielefeld viaduct.
How does it work?
A conventional bomb releases chemical energy: the explosive decomposes into very hot gases in a few microseconds (detonation).
Order of magnitude: a few megajoules per kilogram of explosive (1 kg of TNT ≈ 4.2 MJ), millions of times less than nuclear reactions for the same mass.
The expanding gases violently compress the air: the shock wave weakens very quickly with distance.
A penetrating bomb has a thick steel casing and a delayed fuze: it buries itself in the ground or concrete before exploding.
Much of the energy is then transmitted to the ground (seismic wave) rather than to the air: surface effects are much weaker than for an airburst of the same energy.
Estimated TNT equivalent = mass of explosive × relative effectiveness factor of that explosive (≈ 1.3 for Torpex or H-6, ≈ 1.05 for Tritonal).
Deliberately general explanations: the application provides no design or manufacturing information.
Frequently asked questions
How powerful is Grand Slam?
Grand Slam has an estimated yield of 5.5 t of TNT equivalent, about 23 GJ of energy.
What is the history of Grand Slam?
Used by the RAF in March–April 1945 against viaducts, bridges and submarine pens. On 14 March 1945, a single Grand Slam brought down part of the Bielefeld viaduct, which dozens of raids had failed to cut for good.
What does the Grand Slam explosion look like?
The Bomb Simulator shows the fireball, shock wave and cloud of Grand Slam at real scale, over Paris, London or New York, with the sources and reliability of each value.
Sources
- Grand Slam (bomb) — Wikipedia (overview, to be cross-checked)
Other weapons
- Tallboy — 3.1 t
- FAB-5000NG — 4 t
- FAB-9000 — 4.3 t
- BLU-82 — 5.7 t
- GBU-28 — 0.3 t
- Mk 84 — 0.5 t
- GBU-43/B MOAB — 11 t
- FOAB — 44 t
- FAB-3000 — 1.4 t
- GBU-57 MOP — 3 t
This application is an educational tool. The animations and effect zones are simplified representations meant to illustrate orders of magnitude. They are neither a prediction of the effects of a real weapon nor a military planning tool.