The T-12 Cloudmaker was twice as big and weighed 44,000 lb overall. It was based on the British-designed 22,000lb (10,000kg) Grand Slam created by British aeronautical engineer Barnes Wallis during World War II (20,000kg)
The T-12 Cloudmaker earthquake bomb, a sizable demolition bomb produced by the US from 1944 to 1948.
The T-12 belonged to a small class of bombs made to assault structures like bunkers and viaducts that are impervious to typical “soft” bombs. It accomplished this by having a very thick, hardened nose portion that was made to pierce deeply into structures made of hardened concrete before detonating within the target after a brief delay.
According to r/Warthunder Reddit Community, Barnes Wallis, a British aeronautical engineer, based the T-12 Cloudmaker on the British-designed Grand Slam 22,000 lb (10,000 kg) he created during World War II. The T-12 Cloudmaker was also twice as big as the Grand Slam 44,000 lb (20,000 kg). A hardened, extremely aerodynamic bomb of the biggest weight intended to be dropped from the highest altitude and was the concept for both the Grand Slam and the Cloudmaker.
The ensuing shock wave delivers through the earth into targets after the explosion penetrates deeply into the earth. Structures may be undermined by the ensuing underground void and ground motion. The bomb could also be employed on targets with greater resistance. These kinds of bombs have tail fins that spin the bomb for increased precision and can travel at supersonic speeds.
It was intended to reach a target weight of 42,000 lb (19,000 kg), which is half of the Convair B-36 “Peacemaker” bomber’s maximum payload. 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 had improvements based on testing and calculations rather than being a straightforward scaling up of the M110.
The T-12 Cloudmaker was dropped from a Boeing B-29 Superfortess that had been modified when testing of this new weapon started. Once officially entering service with the USAF, the T-12 Cloudmaker was mainly deployed from the Convair B-36 Peacemaker. Not one, but two of these enormous demolition bombs could be carried by the B-36 Peacemaker. Until 1958, when the B-36 Peacemakers were starting to be deactivated, the T-12 Cloudmaker was still in use.
Additional source: Wikipedia