22,000lb Grand Slam Bomb Print
Written by David Boyd   
Thursday, 01 January 2009 20:55

22,000lb Grand Slam Bomb

Grandslam Bomb

The Grand Slam was an enlarged version of Barnes Wallis' 12,000lb Tallboy bomb. This mammoth bomb was the largest conventional bomb dropped during the Second World War weighing in a 22,400lb - the empty weight of a Wellington bomber was around 18,000lb. The bomb was used on specialised targets such as submarine pens and viaducts, the grandslam would penetrate deep underground and then create a heavy shock wave.  

As with Tallboy the Grandslam was dropped by the Lancaster bomber, several modifications were required including usually the removal of all but the rear turrets, it was however possible to have the rear and mid-upper turrets if the maximum ammunition carried by the rear turret was reduced to 5,000 rounds. Maximum take of weight was 72,000lb and the maximum allowable speed with the bomb attached was 250mph. The bomb caused vibration of the rear fuselage which could be felt in the entire aircraft (this was caused by the crutches for the store and was later fixed). Handling was found to be not entirely satisfactory, though acceptable.

Grandslam bomb specifications

Bomb 22000-lb DP Mk I
Construction Cast Steel
Usual weight 22,400lb (10,181kg)
Charge/weight ratio 42%
Total length 305in (774.7cm)
Body length 46in (116.84cm)
Body diameter 150in (381cm)
Wall thickness 1.75-7.75in (4.44-19.68cm)
Tail length 160in (406.4cm)
Tail width 52in (132.08cm)
Filling Torpex

Sources - AVIA 46 285, AVIA 46 163