The T-12, also known as Cloudmaker, was a purely American general purpose bomb design whose intended weight of 42,000 lbs rose in manufacture to 43,600 lbs, with 41% or 17,600 lbs consisting of high explosives. Nearly twice the size and weight of the Grand Slam, it measured 200 inches long and 54 inches in diameter, was built from six welded steel sections, and reached a total length of 322 inches with its tail assembly. Improvements were made by Ordnance Corps engineers at the U.S. Army's Aberdeen Proving Ground. Its great length made it impossible to stow completely inside carrier aircraft during WWII, so in the summer of 1945 Boeing Aircraft Corp at Wichita, KS modified B-29A S/N 44-62263 to carry one T-12 partially exposed beneath the aircraft. Six inert casing drops from 25,000 ft were conducted on March 5, 1948. The B-36, first flown in 1946, had bomb bays large enough to carry two T-12 bombs, and on January 29, 1949, B-36 S/N 44-92043 flew a 2,900 mile round trip from Ft. Worth, TX to the Muro AAFB bombing range and dropped two T-12 bombs from 35,000 ft and 40,000 ft. The Army Ordnance Dept. placed a wartime order for 100 bombs, and the A.O. Smith Corporation had produced 57 casings when the contract was canceled and the program ended on August 11, 1954.