Aviation History

The story of the T-12 Cloudmaker, the 44,000 lb earthquake bomb carried by the B-36 Peacemaker

Based on the British designed 22,000lb (10,000kg) Grand Slam developed by British aeronautical engineer Barnes Wallis during the Second World War, the T-12 Cloudmaker was twice the size with a total weight 44,000 lb (20,000kg).

The impressive photos in this post feature the T-12 Cloudmaker earthquake bomb, a massive demolition bomb developed from 1944 to 1948 by the US.

The T-12 was one of a small class of bombs designed to attack targets invulnerable to conventional “soft” bombs, such as bunkers and viaducts. It achieved this by having an extremely thick, hardened nose section designed to penetrate deeply into hardened concrete structures and then detonate inside the target after a short time delay.

Based on the British designed 22,000 lb (10,000 kg) Grand Slam developed by British aeronautical engineer Barnes Wallis during the Second World War, according to r/Warthunder Reddit Community, the T-12 Cloudmaker was twice the size with a total weight 44,000 lb (20,000 kg). The Grand Slam and the Cloudmaker were conceived around the same concept: a hardened, highly aerodynamic bomb of the greatest possible weight designed to be dropped from the highest possible altitude. Penetrating deeply in the earth before exploding, the resulting shock wave was transmitted through the earth into targets. The resulting underground cavity and ground motion could also undermine structures. The bomb could also be used against hardened targets. These types of bombs can reach supersonic speeds and have tail fins designed to spin the bomb for greater accuracy.

A Convair crew loads a 44,000 lb T-12 “Grand Slam” type bomb shape into the front bomb bay of a B-36

Originally designed to meet a 42,000 lb (19,000 kg) target weight (one half of the maximum payload for the Convair B-36 “Peacemaker” bomber), with its hardened case was slightly less than 43,000 lb (19,500 kg). The final T-12 weighed 44,000 lb (19,800 kg). This was twice the size of the United States’ previous largest bomb, the 22,000 lb (10,000 kg) M110 (T-14), the American-built version of the British Grand Slam. The T-12 was not a simple scale up of the M110, but incorporated modifications based on testing and calculations.

When the testing of this new weapon began, the T-12 Cloudmaker was dropped from a converted Boeing B-29 Superfortess. Once officially entering service with the USAF, the T-12 Cloudmaker was mainly deployed from the Convair B-36 Peacemaker. The B-36 Peacemaker had the bomb capacity to carry not one, but two of these massive demolition bombs. The T-12 Cloudmaker remained in service until 1958 when the B-36 Peacemakers were beginning to be decommissioned.

Additional source: Wikipedia

Photo credit: Greg Goebel via Wikipedia and Our World

A T-12 dummy stands on compound of US Army Ordnance Museum in Aberdeen, Maryland.
Dario Leone

Dario Leone is an aviation, defense and military writer. He is the Founder and Editor of “The Aviation Geek Club” one of the world’s most read military aviation blogs. His writing has appeared in The National Interest and other news media. He has reported from Europe and flown Super Puma and Cougar helicopters with the Swiss Air Force.

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