B-29 named Enola Gay dropped a nuke over Hiroshima

B-17 replacement

Made near the end of WW2

Got the name "Superfortress" for its size and related to the B-17 "Flying fortress"

Has ball turret gunners on front, back, underbelly, and middle.

Made by Boeing

Made for strategic bombing, unlike the B-17 

10 tons of payload, 4x the amount of the B-17

B-29 named Bockscar dropped the 2nd Nuke on Nagasaki

Some B-29's were made into Tu-4's by the Soviet Union