 At the end of World War II , the U.S. Navy began a design competition on 13 August 1945 for a carrier @-@ based bomber which could carry a 10 @,@ 000 @-@ pound ( 4 @,@ 536 kg ) bomb that was won by North American Aviation . Later that year , the Navy decided that it needed to be able to deliver atomic bombs and that the AJ Savage design would be modified to accommodate the latest Mark 4 nuclear bomb . A contract for three XAJ @-@ 1 prototypes and a static test airframe was awarded on 24 June 1946 . The first prototype made its maiden flight two years later on 3 July 1948 . That same year the US Navy began an interim capability program employing the Lockheed P @-@ 2 Neptune as its first carrier launched nuclear bomber aircraft until the Savage was in service , the Neptune launched using JATO assist but could not land on existing carriers , if launched they had to either ditch at sea after it 's mission or land at a friendly airbase . 
