Model Variants (Including Prototypes)
XB-29 - Prototype
YB-29 - Preproduction model evaluation aircraft
B-29A - Fitted with 4 x Wright R-3350-23 Cyclone Eighteen air-cooled radial piston engines of 2,200 horsepower each.
B-29A-BN - Increased wingspan; four gun upper forward turret.
B-29B - No defensive armament except for single remote controlled tail gun emplacement.
B-29B-BA - Increased bombload; reduced defensive gun armament.
B-29D - Revised engines.
RB-29 - Reconnaissance Model (redesignated from previous RB-29 designation).
SB-29 - Search and Rescue Model
TB-29 - Crew Trainer Model
WB-29 - Weather Reconnaissance Model
KB-29 - Aerial Refueling Tank Model
F-13A - Reconnaissance Model (later redesignated to RB-29).
B-50A - Redesignated from B-29D; revised tail fin and improved engines; 4 Pratt & Whitney R-4360 radial piston engines; reinforced structure; introduced in 1948 with 370 examples produced.
Tu-4 "Bull" - Direct, illegal Soviet copy of captured B-29 systems.
Tu-70 - Soviet designation for Tu-4 dedicated transport variant.