Contents - Hirohito's War
36 LeMay’s B-29 Superfortresses over Japan: Cities in Ashes
[April 1944–August 1945]
[Maps: 36.1, 36.2, 36.3, 36.4]
The Boeing B-29 Superfortress (p 1013) Twentieth Bomber Command in India and China (p 1015) The Failure of High Altitude Precision Bombing (p 1019) Major-General Curtis LeMay (p 1023) The Great Tokyo Air Raid (p 1024) The Firebombing of Japan’s Major Cities (p 1028) The EMPIRE Plan and the Expansion of Firebombing (p 1031) The Mining of Japanese Shipping (p 1033) Japan’s Desperate Last Aerial Weapons (p 1035) The Results and Morality of the Bombing of Japan (p 1036)
The Boeing B-29 Superfortress: The Boeing B-29 known as the Superfortress was originally conceived as a design study requested by the US Army Air Corps in 1938. They wanted a high altitude bomber that would be out of range of enemy fighters and thus capable of daytime attacks. In order to enable high altitude, the cabin would need to be pressurized, a first for an aircraft of this type. Formal specification was issued by the Air Corps in December 1939 for a ‘super-bomber’ and Boeing, in competition with Consolidated Aircraft and Lockheed, succeeded in producing a prototype, which won orders for 250 planes.
The design of the B-29, with its requirements for a large pressured fuselage to enable high altitude flying, made it an unusually technologically advanced plane for the period. In addition to the pressurized cabin, the B-29 had the first computer controlled armament system. Designed by Sperry Corporation, the gun turrets, sighted by periscopes, were operated by a complex and weighty control system. Five General Electric analog computers served the five sightings and were able to calculate airspeed, gravity, temperature and humidity to correct the aiming of the four turrets, each fitted with two (later three) 0.50 Browning M2 machine guns. The complexity of the design was increased by the need to connect the pressurized front and back cockpits with a pressurized ‘crawl’ tunnel, above the unpressurized bomb bay, which connected the two. Produced by Garrett AiResearch in Phoenix Arizona, it was by far the largest pressurized aircraft cabin that had hitherto been attempted. In time the technologies developed for the B-29 formed the bedrock of US technological advance in the post-war period. Boeing in particularly benefitted from a development program that would enable it to become the dominant civil aviation company after the war.
The first run of B-29s each took 150,000 man-hours to build and brought a rush of recruitment by Boeing and their host of sub-contractors. Eventually, improved training and productivity gains brought the build time down to a still not inconsiderable 20,000 man-hours. The cost of the program was prodigious, estimated at US$3.0bn, exceeding even the famed MAN HATTAN Project that cost US$2.0bn. In fact the MANHATTAN Project would not have been possible without the B-29, which was the only plane large enough to carry and deliver the atom bomb.
Manufacturing time apart, the principal difficulty with the B-29 lay with the Wright R-3350 Duplex Cyclone radial engine. It had been developed in 1937 but the management