Boeing B-29 Superfortress

The Boeing B-29 Superfortress (Boeing Model 341/345) was a four-engine heavy bomber propeller aircraft 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.

A B-29 over the Alabama River during transition training at Maxwell Field

Manufacturing

Manufacturing 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 history

The 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 refueling. 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.

Variants and design stages

Unlike many other aircraft designed to play a similar role, the variants of the B-29 were all essentially the same. The developments made between the first prototype XB-29 and any of the three versions flown in combat were all minuscule. The most specialisation was made in modifying planes for non-bombing mission profiles.

The biggest differences were between variants modified for non-bomber missions. In addition to acting as cargo carriers, rescue aircraft, weather ships, and trainers, some were used for odd purposes such as flying relay television transmitters under the name of Stratovision. Other aircraft acted as the mothership for experimental aircraft, including the Bell X-1 and XF-85 Goblin. One modified B-29 was used to develop the Airborne Early Warning program; it was the ancestor of various modern radar picket aircraft.

Some B-29s were modified to act as test beds for various new systems or special conditions, including fire-control systems, cold weather operations, and various armament configurations. Several converted B-29s were used to experiment with aerial refueling. Perhaps the most important tests were conducted by the XB-29G; it carried prototype jet engines in its bomb bay, and lowered them into the air stream to conduct measurements.

B-29 users

USAAF / USAF / US Navy

USAAF

The United States Army Air Force (later United States Air Force) was the principal user of the B-29. USAAF designations included B-29, B-29A, F-13 (Photographic reconnsaissance - later redegignated RB-29/29A), KB-29P aerial refuelling tankers and various experimental aircraft under the designation EB-29.

Several EB-29s were modified with the intention of carrying the McDonnell XF-85 Goblin parasite fighter. One B-29 was as used as the "mother" aircraft for the Bell X-1 research aircraft. On October 14, 1947, Capt Charles E. "Chuck" Yeager was dropped in the X-1 from the B-29 and became the first pilot to exceed speed of sound in the X-1.

US Navy

The US Navy used four B-29s for long-range search missions. The Navy desgination P2B-1S was assigned for the Naval B-29.

One P2B-1S was extensively modified to cary the Douglas D-558-II Skyrocket high-speed rocket-powered research aircraft. The first Skyrocket launch took place on September 8, 1950. The Skyrocket exceeded Mach 2 for the first time on November 20, 1953 (piloted by Scott Crossfield). The last Skyrocket flight took place in December 1956.

Royal Air Force

B-29s were named Boeing Washington B.1 in RAF Service. Eighty-seven B-29s served on loan with RAF Bomber Command from 1950 as a longer-range nuclear-capable bomber pending the introduction of the English Electric Canberra in quantity. Most Washingtons had been returned by 1955 although two or three remained in the UK as gunnery targets. Two RAF Washingtons took part in the SAC bombing competition in 1951 alongside USAF B-29s.

Royal Australian Air Force

Two ex-RAF Washingtons served with the Royal Australian Air Force.

Soviet Air Force VVS

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.

People's Liberation Army Air Force

A number of ex-soviet TU-4 served in the Chinese PLAAF until the late 1960s

Noteworthy survivors

Airworthy aircraft

B-29A-60-BN 44-62070 "Fifi" belonging to the Commemorative Air Force is the only airworthy B-29 in the world at present. Although two other aircraft are intended to be returned to airworthy condition in the long-term.

B-29-70-BW 44-69972 "Doc" is a Korean War veteran which has been used as a radar trainer and ballistic missile target. The airframe was acquired by the United States Aviation Museum (western division) based at Inyokern, California for eventual restoration to flying status. It is now at the Boeing plant in Wichita, Kansas (where it was originally built) for eventual restoration to flying status.

P2B-1S BuNo 84029 (Formerly B-29-95-BW 45-21787) "Fertile Myrtle" (which carried the Douglas D-558-II Skyrocket research aircraft) was donated to an aviation museum in Oakland, California in 1984. It was sold to the Kermit Weeks Aviation Museum of Miami, Florida, and is on the US Civil register as N29KW. There may be an attempt to restore this plane to flying condition, using as parts some airframes acquired from the US Naval Weapons Center at China Lake, California.

Preserved veterans

A number of B-29s which were used operationally in the Second World War survive in museums in the United States

B-29-40-MO 44-86292 "Enola Gay" - A "Silverplate" (A-Bomb Carrier) conversion. 393rd Bomb Squadron, 509th Composite Group. On Aug 6, 1945 dropped "Little Boy" Uranium Atomic bomb on Hiroshima, Japan . For many years was in storage at Paul Garber facility at National Air and Space Museum, Washington, D.C. recently re-assembled after lengthy restoration and displayed at the Smithsonian's Steven F. Udvar-Hazy Center at Dulles International Airport.

B-29-35-MO 44-27297 "Bockscar" A "Silverplate" (A-Bomb Carrier) conversion. 393rd Bomb Squadron, 509th Composite Group. On Aug 9, 1945 dropped the "Fat Man" Plutonium Atomic Bomb on Nagasaki, Japan. Stored for many years and now on display at the National Museum of the United States Air Force at Wright-Patterson Air Force Base near Dayton, Ohio.

B-29-60-BW 44-69729 "T-Square" . 44-69729 was assigned to the 875th Bomb Squadron, 498th Bomb Group and completed thirty-seven bombing missions. Converted to KB-29 (aerial refueling tanker) in June 1949. It was first put on display in 1996 at the Museum of Flight in Seattle, Washington. The restoration used parts from three other B-29s

B-29-75-BW 44-70016 "Sentimental Journey" Originally flew with the 330th Bomb Group, 20th Air Force from Guam, now displayed at the Pima Air & Space Museum in Tucson, Arizona.

B-29-80-BW 44-70113 flew with the 73rd Bomb Wing 20th Air Force. Decommissioned in 1956 and stored until the Marietta B29 Association sponsored restoration in 1994. Now on display at Dobbins AFB, Georgia.

There are currently between 35 and 40 B-29s preserved worldwide. Some airframes recovered from the US Naval Weapons Center at China Lake are still being stored.

There is at least one confirmed Soviet Tu-4 surviving. It is located at The Monino Air Force Museum, which is located on the grounds of the Yuri Gagarin Air Force Academy, outside Moscow. There are unconfirmed reports of two additional Tu-4's at The Peoples Air Museum. The Tu-4 at Monino was tasked with bombing the Budapest headquarters of the Hungarian rebel movement during the 1956 rebellion; although the mission was planned and rehearsed, it was never carried out. Unconfirmed rumors also claim the existence of at least 15 other Tu-4 airframes somewhere in Russia. Two Soviet-built Tu-4's survive at the National Air Museum near Beijing, China. One of these has been converted to an AWACS-type aircraft, the other carries an unmanned spy plane under each wing.

Specifications (B-29)

General characteristics

Crew: 10: pilot, co-pilot, flight engineer, bombardier, navigator, radio operator, side gunners (two), top gunner, and tail gunner
Length: 99 ft 0 in (30.2 m)
Wingspan: 141 ft 3 in (43.1 m)
Height: 27 ft 9 in (8.5 m)
Wing area: 1736 ft² (161.3 m²)
Empty: 74,500 lb (33,800 kg)
Loaded: 120,000 lb (54,000 kg)
Maximum takeoff: 133,500 lb (60,560 kg)
Powerplant: 4× Wright R-3350-23 supercharged radial engines, 2,200 hp (1600 kW) each

Performance

Maximum speed: 357 mph (574 km/h)
Cruising speed: 220 mph (350 km/h)
Combat range: 3,250 miles (5,230 km)
Ferry range: 5,600 miles (9,000 km)
Service ceiling: 33,600 ft (10,200 m)
Rate of climb: 900 ft/min (270 m/min)
Wing loading: 69.12 lb/ft² (337 kg/m²)
Power/mass: 0.073 hp/lb (121 W/kg)

Armament

12× .50 in (12.7 mm) M2 machine guns in remote controlled turrets
1× 20 mm M2 cannon in tail
20,000 lb (9,072 kg) of bombs

References

Bowers, Peter M. (1999). Boeing B-29 Superfortress. Stillwater, Minnesota: Voyageur Press. ISBN 0933424795.
LeMay, Curtis and Bill Yenne (1988). Super Fortress. Berkley Books. ISBN 0425118800.
Mann, Robert A. (2004). The B-29 Superfortress: A Comprehensive Registry of the Planes and Their Missions. Jefferson, North Carolina: McFarland & Company. ISBN 0786417870.
Pace, Steve (2003). Boeing B-29 Superfortress. Ramsbury, Marlborough, Wiltshire, United Kingdom: Crowood Press. ISBN 1861265816.
Vander Meulen, Jacob (1995). Building the B-29. Washington, D.C.: Smithsonian Books. ISBN 1560986093).
(The economic aspect of the B-29 program)
Wheeler, Keith (1982). Bombers over Japan. Virginia Beach, Virginia: Time-Life Books. ISBN 0809434296.
"Boeing B-29 Superfortress." Encyclopedia of American Aircraft. Accessed on October 26, 2004.
"Boeing B-29 "Superfortress". USAF Museum. Accessed on October 10, 2004.