The four-engine, propeller-powered Boeing B-50 bomber was among the last piston-powered bombers built during an era that was to be dominated by jets, particularly the B-47 and the B-52. The B-50 evolved from the B-29D, but because it included so many improvements, it was redesignated the B-50A, with 59 percent more power than the B-29. Other improvements were more aerodynamic nacelles, larger flaps, fast-retracting ball-screw landing gear, hydraulic rudder boost, hydraulic nosewheel steering and heated-wing deicing.