The B29 bomber was built in 1944 upon experimental systems and provided a pressurized cockpit, nose, and a shaft leading along the ship to the unpressurized launch bays. The second is the atomic bomb. Roosevelt became aware that the Zazis were trying to create one, so he started the Manhatten Project which was a group of skilled scientists tasked with creating their own atomic bomb. Once it was complete we dropped it on Japan in 1945.
Wrote this myself, hope it helps!