Production Superfortresses were similar in appearance, with a single tail and a narrow high-aspect ratio wing whose area was increased by 19% when the Fowler flaps were extended. The retractable tricycle gear used double main wheels of B-17-size.
The crew of eleven sat in pressurized compartments, beginning with the bombardier in the circular nose with his bomb and gun sights, pilot and co-pilot protected by panels of armor and bulletproof glass, then the flight engineer, radio operator, and navigator. That front compartment was connected by a 33-foot long tunnel over the double bomb bays to the rear compartment containing three gunners and the radar man, all protected by an armor bulkhead.
Like the main cabins, the separate tail gunner’s compartment was also protected and pressurized to maintain an internal altitude of 8,000 feet up to an actual altitude of 30,000 feet. Up to forty 500 or sixteen 1,000-pound bombs could be carried in the tandem bomb bays, or replaced by up to four 640-gallon drop tanks. An APQ-13 radar dome could be extended below between the bomb bay doors.
The distinguishing armament feature was an elaborate General Electric fire-control system with computing sights in the nose and in rear top and side blisters directing four remote-controlled turrets turning a full 360-degrees. Each had two .50-caliber guns, and the tail gunner had two .50-caliber and one 20-mm gun moving in a 30-degree arc.
The first YB-29-BW flew on June 26, 1943, in Kansas with the R-3350-21, three-bladed propellers, and a full armament system. R-3350-23 engines and Hamilton Hydromatic four-bladed propellers were introduced on the first production B-29-1-BW Superfortress accepted on September 21, 1943, and by the year’s end at Wichita, 40 B-29-1 and 33 B-29-5-BW had been accepted, the latter omitting camouflage paint. In 1944, 722 rolled out of the plant, taking block numbers to B-29-55-BW.
Unfortunately, acceptance didn’t mean combat-ready, for the heaviest plane in mass production had a multitude of minor mechanical items that needed fixing. The engines were a constant cause of concern; and the R-3350-23 had to be replaced with -23A models before going overseas. Newer Cyclone engine models with fuel injection, the R-3350-41 and -57, were introduced in 1945. Aircraft complexity had increased factory man-hours from 200,000 on each B-17 to three million on the B-29, and average flyaway cost per B-29 during the war was $639,188.
A new factory near Atlanta managed by Bell Aircraft began in November 1943 by assembling five B-29-1-BA bombers from Wichita parts and adding 200 of its own in 1944. Martin’s Omaha factory also began in December 1943 with five B-29-1-MO bombers from Wichita parts and added 95 from May to December 1944. Boeing’s Renton plant began B-29A-1-BN deliveries in January 1944 with a new wing center section structure, and completed 139 in 1944.
The first 415 B-29s from Wichita (blocks 1 to 40-BW) had ten .50-caliber guns with 5,000 rounds, and 100 rounds for the 20-mm gun. In July 1944, beginning in the B-29-40-BW, B-29-15-BA, B-29-5-MO, and B-29A-20-BN blocks, there were four guns in the upper front turret. The 20-mm gun, unpopular with crews, was omitted after blocks B-29-50-BW, B-29-15-BA, B-29-20-MO, and B-29A-10-BN, leaving just the twin fifties. These were the only guns remaining when all four turrets were removed to improve the range and speed of those aircraft selected for night raids later in the war.
Although B-29 production closed with the cancellation of 5,092 planes after the war ended in September 1945, Renton was allowed to resume deliveries in November with another 50 B-29A-70-BNs and, with new forward upper turrets, 19 B-29A-75-BNs. The last was delivered on June 10, 1946, for a total of 1,119 B-29As. There were 1,634 B-29s from Wichita, and Martin delivered 536 B-29-MO.
Bell alternated between 357 B-29-BA and 311 B-29B-BA models. The B-29B was a night-bomber with APQ-7 Eagle bombing radar instead of the APS-13, no turrets, and APG-15 radar for the tail guns; two .50-caliber, or three in the last 260 planes. The B-29B was used entirely by the 315th Bomb Wing’s attacks on the oil industry. Altogether, 3,960 B-29s of all models were accepted by the AAF.
Six cameras were fitted in the rear section of 118 photo-recon versions known as the F-13 and F-13A and the first, converted from a B-29-40-BW, flew on August 4, 1944. Some retained turrets and others did not. An F-13A flew over Tokyo on November 1, 1944, locating targets for the B-29 bombing campaign soon to begin. Many such vital sorties were made and followed by others to evaluate damage.
Extra armament had been fitted to the fourth YB-29 to test it as an escort fighter, like the B-40. Two .50s were mounted in a nose turret and in each of four side blisters. The top and bottom turrets were retained with a 20-mm gun added to the lower turret and a 37-mm gun in the tail, for a total of 22 guns.
One experimental B-29-25-BW tested in October 1944 replaced the remote-controlled system with two conventional Martin top turrets, two Sperry “ball” turrets underneath, a one-gun Emerson barrette on each side of the nose, and a manual gun at each side blister. Production aircraft, however, kept the 12-gun configuration, except for the two-gun night bombers.