The B-29 heavy bomber set new standards in performance, armament and range. It was used only in the Pacific, finally dropping the A-bombs on Hiroshima and Nagasaki. After the war it became the main means of delivery for nuclear bombs. The USSR copied it as the Tu-4. The KB-29 was the tanker version of the B-29, the SB-29 the search & rescue version, carrying a lifeboat; the DB-29 was a drone controller, the TB-29 a trainer, the RB-29 a reconnaissance aircraft. Some B-29s were also used as launch aircraft for research aircraft like the X-1 and X-2. 3970 were built. The type was developed into the more powerful B-50.
The Boeing B29 Superfortress was the largest bomber to enter service in World War Two. B29's played a major part in the overall bombing campaign in the Far East and two B-29 Superfortress bombers ('Enola Gay' and 'Bockscar') took part in the atomic bomb raids on Hiroshima and Nagasaki in August 1945.
The B29 weighed almost 60 tons and its Wright Cyclone air-cooled radial engines were considered to be the most powerful of the time developing 2,200 hp in each engine. The four engines gave it just under 9,000 hp. The B29 was the first production aircraft to have fully pressurised crew compartments for its eleven crew. The B29 was also the first plane to have a central gunnery-control system operated by remote control. For all its firsts in terms of plane design, the B29 was rushed into service and contained a number of design faults that had to be corrected as more and more were produced.
The B29 was designed to fly at 400 mph when it was not loaded. It was able to fly at 30,000 feet and to carry a 2000 lb bomb load 5,000 miles. However, on smaller distances, the B29 was capable of carrying sixteen 500lb bombs in its after bomb bay and another sixteen 500lb bombs in its forward bomb bay.
It has massive armaments: ten .50 inch machine guns in turrets in both its upper and lower fuselage. In later models, the B29's forward upper turret had a four gun battery and a 20 mm cannon supplemented the tail gun. Each gun was served by a 1,000 round bullet belt.
B-29 SuperfortressThe Boeing B-29 Superfortress (Boeing Model 341/345) was a four-engine heavy bomber flown by the United States Army Air Force. It was one of the largest aircraft to see active service during World War II. It was one of the most advanced bombers of its time, featuring innovations such as a pressurized cabin, a central fire-control system, and remote-controlled machine gun turrets. It was designed as a high-altitude daytime bomber, but flew more low-altitude nighttime incendiary bombing missions. It was the primary aircraft in the U.S. firebombing campaign against Japan in the final months of World War II, and B-29s carried the atomic bombs that destroyed Hiroshima and Nagasaki. Unlike many other bombers, the B-29 remained in service long after the war ended, a few being employed as flying television transmitters for Stratovision. By the time it was retired in the 1960s, some 3,900 planes had been built.
DevelopmentThe development of the B-29 can be traced to Project A, an 1934 Army feasibility study for a bomber that could carry one ton of bombs 5,000 miles. This was an ambitious goal for an air force whose largest bombers at that time were two-engine models. In June of that year, Boeing presented the Army with the Boeing Model 294. The Army liked the design, and eventually designated it the XB-15. The single prototype dwarfed anything on active duty at the time; its empty weight was only 13 percent less than that of the B-29. The B-29 shows remarkable resemblance with the German Messerschmitt Me 264 Amerika developed one year earlier.
In August 1934, Boeing also began work on a slightly less ambitious design, the Model 299. This design became the B-17 Flying Fortress. In 1938, Boeing agreed to do a design study on a more advanced development of the B-17, the Model 322, which would feature a pressurized cabin. However, the project was deemed infeasible and abandoned.
In March 1936, a team lead by Lysle Wood began work on an updated XB-15, the Model 316. This plane featured the all-glass nose that would make the B-29 distinctive. Designated the Y1B-20, it was 17 percent heavier than the eventual B-29. The Army was not interested. Boeing continued heavy bomber development in 1938 and 1939 with Models 330, 333, 333A, 333B, 334, and 334A. In August 1939 they began work on the Model 341, featuring a much improved wing: the Boeing Model 115 airfoil.
Around 1938, General Henry H. 'Hap' Arnold, the head of the Army Air Corps, was growing alarmed at the possibility of war in Europe and in the Pacific. To prepare the Air Corps, Arnold created a special committee chaired by Brigadier General W. G. Kilner; one of its members was Charles Lindbergh. After a tour of Luftwaffe bases, Lindbergh became convinced that Nazi Germany was far ahead of other European nations. In a 1939 report, the committee made a number of recommendations, including development of new long-range heavy bombers.
When war broke out in Europe, Arnold requested design studies from several companies on a Very Long-Range bomber capable of travelling 5,000 miles (8,000 km). Part of Arnold's motivation for these studies was the fear that Britain might fall to the Nazis. In that event, it would be imperative that the Army Air Force have a bomber capable of flying round-trip from the U.S. East Coast to Europe to strike targets on the European mainland. Approval was granted on December 2. This request, R-40B, fitted perfectly with the research Boeing was doing at the time.
In January 1940, the B-17 was entering service and the somewhat larger Consolidated B-24 was still more than a year away. At this time, the Air Corps issued a request for proposals for a much larger bomber, which was to have the range for operation over the Pacific; this bomber would serve in the inevitable war with Japan. Four firms submitted design studies: the Boeing XB-29, Lockheed XB-30, Douglas XB-31, and Consolidated XB-32. Douglas and Lockheed soon withdrew, in part because Boeing was well ahead of them in the design process. In 1940, September, Boeing and Consolidated were awarded development contracts for the XB-29 and the XB-32, respectively.
In early 1940, the Army Air Corps analysed the performance of bombers used in Europe against the Luftwaffe, and requested that the B-29 have self-sealing fuel tanks, more machine guns, and higher-caliber guns. Boeing incorporated these into a redesign of the Model 341, and resubmitted it to the Army Air Corps as Model 345, which would become the XB-29. Impressed by the mock-up completed in the spring 1941, the Army Air Corps had placed a massive order for 1,500 B-29s, a year before the prototype would fly for the first time on September 21, 1942. A long-range bomber was urgently needed, so service testing proceeded largely in tandem with production. The first B-29 rolled off the assembly line two months after the first service test flight. In under a year, the B-29 was in full-scale production.
The B-29 was a giant airplane, nearly twice as heavy as the heaviest previously serving bomber. Mid-set wings with a high aspect ratio gave it exceptional range. To reduce the dangerously high landing speed of the B-29, it was fitted with enormous Fowler flaps. It had three separate pressurized crew compartments: one in the nose, a second aft of the wing for the gunners, and an isolated compartment for the tail gunner. Rather than the traditional bulky manned gun turrets, Boeing used small, remote-control units 'networked' together with an analog computer that compensated for factors such as air temperature and bullet drop. This system was very difficult to develop, but it proved effective. There are several accounts of 'healthy' B-29s peeling out of formation to drive off successfully fighters preying on damaged brethren.
ManufacturingManufacturing the B-29 was an immense task. It involved four main factories: two Boeing plants at Renton, Washington and Wichita, Kansas, a Bell plant at Marietta, Georgia, and a Martin plant at Omaha, Nebraska. Thousands of subcontractors were involved in the project. Because of its highly advanced design, challenging requirements, and immense pressure for production, development was deeply troubled. The first prototype crashed during testing, killing the entire crew and several ground personnel. Changes to the production craft came so often and so fast that in early 1944, B-29s would leave the production lines and fly directly to modification depots for extensive rebuilds to incorporate the latest changes. This 'battle of Kansas' nearly sank the program, which was only saved by General Hap Arnold's direct intervention. It would still be nearly a year before the aircraft was operated with any sort of reliability.
The most common cause of maintenance headaches and catastrophic failures, even more so than the advanced gunnery system, was the engine. Though the Wright R-3350 would later become a trustworthy workhorse in large piston-engined aircraft, early models were beset with dangerous reliability problems. It had an impressive power-to-weight ratio, but this came at a heavy cost to durability. Worse, the cowling Boeing designed for the engine was too close (out of a desire for improved aerodynamics), and the early cowl flaps caused problematic flutter and vibration when open in most of the flight envelope.
These weaknesses combined to make an engine that would overheat regularly when carrying combat loads; it frequently swallowed its own valves. The resulting engine fires were exacerbated by a crankcase designed mostly of magnesium alloy. The heat was often so intense the main spar burned through in seconds, resulting in catastrophic failure of the wing. This problem would not be fully cured until the aircraft was re-engined with the more powerful Pratt & Whitney R-4360 'Wasp Major' in the B-29D/B-50 program, which arrived too late for World War II. Pilots, including the present-day pilots of the Commemorative Air Force's Fifi, describe flight after takeoff as being an urgent struggle for airspeed; generally, flight after takeoff should consist of striving for altitude. Radial engines need that airflow to keep cool, and failure to get up to speed as soon as possible could result in an engine failure and risk of fire.
Operational historyThe initial plan was to use B-29s to attack Japan from airfields in southern China, with the main base in India, and to attack other targets in the region from China and India as needed. This was an extremely costly scheme, as there was no overland connection available between India and China, and all the supplies had to be flown over the Himalayas. The first B-29s started to arrive in India in early April, 1944. The first B-29 flight to airfields in China (over the Himalayas, or "The Hump") took place on 24 April 1944. The first B-29 combat mission was flown on 5 June 1944, with 77 out of 98 planes launched from India bombing the railroad shops in Bangkok (5 B-29s were lost to non-battle causes).
On June 15, 1944, 47 B-29s launched from Chengtu in China bombed the Imperial Iron and Steel Works at Yawata, Japan. This was the first attack on Japanese islands since the Doolittle raid in April, 1942. The first B-29 combat loss occurred during this raid, with 1 B-29 destroyed on the ground by Japanese fighters after an emergency landing. Because of the extreme cost of operations, the raids against Japan from Chinese airfields continued at relatively low intensity. Japan was bombed on: 7 July 1944 (14 B-29s), 29 July (70+), 10 August (24), 20 August (61), 8 September (90), 26 September (83), 25 October (59), 12 November (29), 21 November (61), 19 December (36) and for the last time on 6 January 1945 (49). B-29s were withdrawn from airfields in China by the end of January, 1945. Throughout this period B-29 raids were also launched from China and India against many other targets throughout South-East Asia. However, the entire B-29 effort was gradually shifted to the new bases in the Marianas, with the last B-29 combat mission from India flown on March 29, 1945.
The need to use inconvenient bases in China for attacks against Japan ceased after the capture of the Marianas islands in 1944. On the islands of Tinian, Saipan and Guam a series of airfields were built, which became the main bases for the large B-29 raids against Japan in the final year of the war. The islands could be easily supplied by ship. The first B-29 arrived on Saipan on 12 October 1944, and the first combat mission was launched from there on 28 October 1944, with 14 B-29s attacking the Truk atoll. The first mission against Japan from bases in the Marianas was flown on 24 November 1944, with 111 B-29s sent to attack Tokyo. From that point ever more intense raids were launched regularly until the end of the war. These attacks succeeded in devastating all large Japanese cities and gravely damaged Japan's war industries.
Perhaps the most recognized B-29 is the Enola Gay, which dropped the atomic bomb 'Little Boy' on Hiroshima on 1945 August 6. The Bockscar, also a B-29, dropped 'Fat Man' on Nagasaki three days later.
The B-29 was used in World War II only in the Pacific Theatre. It was later used in the Korean War, over the course of which they flew 20,000 sorties and dropped 200,000 tons (180,000 tonnes) of bombs. 3970 of the aircraft were built before they were retired in 1960. The B-29 was soon made obsolete by the development of the jet engine. With the arrival of the mammoth B-36, the B-29 suffered its first ignominy by being classified a medium bomber with the new Air Force. However, the later B-29D/B-50 variant was good enough to handle auxiliary roles such as air-sea rescue, electronic intelligence gathering, and even air-to-air refuelling. It was replaced in its primary role during the early 1950s by the Boeing B-47 Stratojet, which in turn was replaced by the Boeing B-52 Stratofortress. The final active duty variants were phased out in the mid 1960s.
Shortly after World War II, the Tupolev design bureau in the Soviet Union manufactured a near-copy of the B-29, the Tupolev Tu-4, based on reverse engineering of three interned early-model B-29s. Some of these remained in service into the 1960s in the Soviet Union. All but one of the Tu-4s were scrapped in the 1960s. The lone example of a Tu-4 known to exist today is located at the Yuri Gagarin Air Force Academy near Moscow, as a static display. This particular airplane was tasked with bombing the Budapest headquarters of the Hungarian rebel movement during the 1956 rebellion; but although the mission was rehearsed it was never put into play.
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