The superfortress was a larger, faster bomber used by the american army air force in the last months of world war ii. it was also able to carry a larger payload than other american bombers. for what reason would it need to carry a larger payload?

It needed to carry as many bombs as possible so that it could destroy as much as possible without having to return for resupply and fuel refill. In addition, it was also the bomber that carried the nuclear bombs that were thrown on Hiroshima and Nagasaki, which was a job which regular bombers would not be able to do.