| B-29 Superfortress | |
|---|---|
| A USAAF B-29 Superfortress | |
| Role | Strategic bomber |
| Manufacturer | Boeing |
| First flight | 21 September 1942 |
| Introduction | 8 May 1944 |
| Retired | 21 June 1960 |
| Status | 1 airworthy, 1 in restoration and several in whole or part in museum collections |
| Primary users | United States Army Air Forces United States Air Force Royal Air Force |
| Produced | 1943–1946[1] |
| Number built | 3,970 |
| Unit cost | US$639,188 ($8.62 million in today's dollars)[2] |
| Variants | All models KB-29 Superfortress XB-39 Superfortress Boeing XB-44 Superfortress Boeing B-50 Superfortress Tupolev Tu-4 |
The B-29 Superfortress is a four-engine propeller-driven heavy bomber designed by Boeing that was flown primarily by the United States Air Forces in late-World War II and through the Korean War. The B-29 was one of the largest aircraft to see service during World War II. A very advanced bomber for this time period, it included features such as a pressurized cabin, an electronic fire-control system, and remote-controlled machine-gun turrets. The name "Superfortress" was derived from that of its well-known predecessor, the B-17 Flying Fortress. Though the B-29 was designed as a high-altitude daytime bomber, in practice it actually flew more low-altitude nighttime incendiary bombing missions. It was the primary aircraft in the American firebombing campaign against the Empire of Japan in the final months of World War II, and carried out the atomic bombings that destroyed Hiroshima and Nagasaki. Unlike many other World War II-era bombers, the B-29 remained in service long after the war ended, with a few even being employed as flying television transmitters for the Stratovision company.
The B-29 served in various roles throughout the 1950s. The British Royal Air Force flew the B-29 and used the name Washington for the type, replacing them in 1953 with the Canberra jet bomber and the Soviet Union produced an unlicensed reverse-engineered copy as the Tupolev Tu-4. The B-29 was the progenitor of a series of Boeing-built bombers, transports, tankers, reconnaissance aircraft and trainers including the B-50 Superfortress (the first aircraft to fly around the world non-stop) which was essentially a re-engined B-29. The type was finally retired in the early 1960s, with 3,970 aircraft in all built. While dozens of B-29s have survived through today as static displays, only one remains on active flying status.
A transport derived from the B-29 was the C-97, first flown in 1944, followed by its commercial airliner variant, the Boeing Model 377 Stratocruiser in 1947. This bomber-to-airliner derivation was similar to the B-17/Model 307 evolution. The tanker variant of the B-29 was introduced in 1948 as the KB-29, followed by the Model 377-derivative KC-97 introduced in 1950. Later jet-powered models from Boeing carried on the lineage, including the B-47 Stratojet and B-52 Stratofortress bombers, as well as the "Dash 80", from which today's modern airliners are evolved. A heavily modified line of outsized-cargo variants of the B-29-derived Stratocruiser is the Guppy/Mini Guppy/Super Guppy which remain in service today with operators such as NASA.
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Boeing began work on pressurized long-range bombers in 1938, when, in response to a United States Army Air Corps request, it produced a design study for the Model 334, a pressurized derivative of the Boeing B-17 Flying Fortress with nosewheel undercarriage. Although the Air Corps did not have money to pursue the design, Boeing continued development with its own funds as a private venture,[3] so that when, in December 1939, the Air Corps issued a formal specification for a so called "superbomber", capable of delivering 20,000 lbs of bombs to a target 2,667 mi (4,290 km) away and capable of flying at a speed of 400 mph (640 km/h), they formed a starting point for Boeing's response.[4]
Boeing submitted its Model 345 on 11 May 1940,[5] in competition with designs from Consolidated Aircraft (the Model 33, later to become the B-32),[6] Lockheed (the Lockheed XB-30),[7] and Douglas (the Douglas XB-31).[8] Douglas and Lockheed soon abandoned work on their projects, but Boeing received an order for two flying prototypes, given the designation XB-29, and an airframe for static testing on 24 August 1940, with the order being revised to add a third flying aircraft on 14 December. Consolidated continued to work on its Model 33 as it was seen by the Air Corps as a backup in case of problems with Boeing's design.[9] An initial production order for 14 service test aircraft and 250 production bombers was placed in May 1941,[10] this being increased to 500 aircraft in January 1942.[5] The B-29 featured a fuselage design with circular cross-sections. The circle, being the geometry of minimum perimeter for a given area, is the theoretical ideal for minimum structural weight to prevent deformation due to strong pressurization forces. For a 3-dimensional volume, the minimum surface is a sphere, however drag considerations shift the fuselage geometry optimization toward a circular cross-section cylindrical design with taper. This basic geometry has persisted in airliner design from the Model 307 through today's 787. The need for pressurization in the cockpit area also led to the B-29 having the only "stepless" cockpit design, without a separate windscreen for the pilot, on an American combat aircraft of World War II.
Manufacturing the B-29 was a complex task. It involved four main-assembly factories: a pair of Boeing operated plants at Renton, Washington, and Wichita, Kansas, a Bell plant at Marietta, Georgia ("Bell-Atlanta"), and a Martin plant at Omaha, Nebraska ("Martin-Omaha").[5][11] Thousands of subcontractors were involved in the project.[12] The first prototype made its maiden flight from Boeing Field, Seattle on 21 September 1942.[11] Because of the aircraft's highly advanced design, challenging requirements, and immense pressure for production, development was deeply troubled. The second prototype, which, unlike the unarmed first, was fitted with a Sperry defensive armament system using remote-controlled gun turrets sighted by periscopes,[13] first flew on 30 December 1942, this flight being terminated due to a serious engine fire. On 18 February 1943 the second prototype experienced an engine fire and crashed. [14] Changes to the production craft came so often and so fast that in early 1944, B-29s flew from the production lines directly to modification depots for extensive rebuilds to incorporate the latest changes. The Air Force–operated modification depots struggled to cope with the scale of work required, with a lack of hangars capable of housing the B-29 combined with freezing cold weather further delaying the modification, such that at the end of 1943, although almost 100 aircraft had been delivered, only 15 percent were airworthy.[15][16] This prompted an intervention by General Hap Arnold to resolve the problem, with production personnel being sent from the factories to the modification centers to speed modification of sufficient aircraft to equip the first Bomb Groups in what became known as the "Battle of Kansas". This resulted in 150 aircraft being modified in the six weeks between 10 March and 15 April 1944.[17][18]
The most common cause of maintenance headaches and catastrophic failures was the engine.[17] Although the Wright R-3350 later became a trustworthy workhorse in large piston-engined aircraft, early models were beset with dangerous reliability problems. This problem was not fully cured until the aircraft was fitted 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. Interim measures included cuffs placed on propeller blades to divert a greater flow of cooling air into the intakes, which had baffles installed to direct a stream of air onto the exhaust valves. Oil flow to the valves was also increased, asbestos baffles installed around rubber push rod fittings to prevent oil loss, thorough pre-flight inspections made to detect unseated valves, and frequent replacement of the uppermost five cylinders (every 25 hours of engine time) and the entire engines (every 75 hours).[N 1][17]
Pilots, including the present day pilots of the Commemorative Air Force’s Fifi, the last remaining flying B-29, describe flight after takeoff as being an urgent struggle for airspeed (generally, flight after takeoff should consist of striving for altitude). Radial engines need airflow to keep them cool, and failure to get up to speed as soon as possible could result in an engine failure and risk of fire. One useful technique was to check the magnetos while already rolling rather than from a "braked" start.[19]
In wartime, the B-29 was capable of flight up to 40,000 feet (12,000 m), at speeds of up to 350 mph (true airspeed). This was its best defense, because Japanese fighters of that day could barely get that high, and few could catch the B-29, even if they were at altitude and waiting. Only the heaviest of anti-aircraft weapons could reach it, and since the Axis forces did not have proximity fuzes, hitting or damaging the aircraft from the ground in combat was next to impossible.
With the revolutionary Central Fire Control System (CFCS), the B-29 had four remote-controlled turrets, each armed with two .50 cal M2/AN machine guns.[N 2] Four gunners were able to control these turrets with the use of four General Electric-made analog computers, one above the Norden bombsight in the nose[N 3] and three in a pressurized compartment in the rear fuselage, which featured clear blown sighting blisters. The gunner manning the sight in the upper rear station was the "Central Fire Control gunner", whose job was to allocate turrets to each of the other three gunners, avoiding confusion in the heat of battle. The CFCS had (at that time) a highly advanced analog computer that corrected for the B-29's airspeed, the target's speed, target lead, gravity, temperature and humidity.[20][21][22] Because of this, the .50 caliber machine guns of the B-29 had a maximum effective range of 1,000 yards (910 m), double the range of the manually aimed machine guns of the B-17 Flying Fortress. The tail gunner could only control his own weapons (two M2/AN Brownings plus, in early production B-29s, a 20 mm M2 cannon) and the lower rear turret. After World War II, the tail guns eventually got their own APG-15 gun control radar sets.[20][21]
In early 1945, with a change of role from high-altitude day bomber to low-altitude night bomber, LeMay reportedly ordered the removal of most of the defensive armament and remote-controlled sighting equipment from his B-29s so that they could carry greater fuel and bomb loads.As a consequence of this requirement, Bell Marietta (BM) produced a series of 311 B-29Bs that had turrets and sighting equipment removed, except for the tail position, which initially had the two .50 cal Browning machine guns and single M2 cannon with the APG-15 radar fitted as standard. This armament was quickly changed to three .50 caliber Brownings. This version also had an improved APQ-7 "Eagle" bombing-through-overcast radar fitted in an airfoil shaped radome under the fuselage. Most of these aircraft were assigned to the 315th Bomb Wing, Northwest Field, Guam.[23]
The crew enjoyed, for the first time in a bomber, full-pressurization comfort. This first-ever cabin pressure system for an Allied production bomber was developed for the B-29 by Garrett AiResearch. [N 4] The nose and the cockpit were pressurized, but the designers were faced with deciding whether to have bomb bays that were not pressurized, between fore and aft pressurized sections, or a fully pressurized fuselage with the need to de-pressurize to drop their loads. The decision was taken to have a long tunnel over the two bomb bays so that crews could crawl back and forth between the fore and aft sections, with both areas and the tunnel pressurized. The bomb bays were not pressurized.[24]
In flight, the pilot called for engine and flap settings instead of moving the throttles and the flap levers himself. Another innovation was the number of calculations the crew had to perform before and during the mission. Prior to the B-29, flight manuals provided only approximate performance figures, and pilots relied largely on instinct and experience. The B-29 manual had charts to compute takeoff and landing speeds based on weight, elevation and temperature. Finding the optimum power settings for cruising speed required consideration of the cruising altitude, outside temperature, aircraft weight, and desired true airspeed. The power settings were recalculated every two hours or with every change in altitude. These types of computations are routine in modern civil and military aviation, but they were an innovation in 1944. The benefits of improved range and performance were irrefutable.
Unlike aircraft such as the Consolidated B-24 Liberator, the B-29 lacked boosted controls. As a consequence they required considerable physical strength to operate.[25] As it was, most aircrews found the B-29 to be relatively mild-mannered.
Though it could be flown with only two engines once airborne, the bomber suffered from engine overheating throughout its service, and several B-29s crashed in Saipan after single engine failures on takeoff at full gross weight.
The initial plan, implemented at the direction of President Franklin D. Roosevelt as a promise to China and called Operation Matterhorn, was to use B-29s to attack Japan from four forward bases in southern China, with five main bases in India, and to attack other targets in the region from China and India as needed.[26] The Chengdu region was eventually chosen over the Guilin region to avoid having to raise, equip, and train 50 Chinese divisions to protect the advanced bases from Japanese ground attack.[27] The XX Bomber Command, initially intended to be two combat wings of four groups each, was reduced to a single wing of four groups because of the lack of availability of aircraft, automatically limiting the effectiveness of any attacks from China.
This was an extremely costly scheme, as there was no overland connection available between India and China, and all supplies had to be flown over the Himalayas, either by transport aircraft or by the B-29s themselves, with some aircraft being stripped of armor and guns and used to deliver fuel. 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 B-29s launched from India bombing the railroad shops in Bangkok and Thailand. Five B-29s were lost during the mission, not to hostile fire.[26][28]
On 15 June 1944, 68 B-29s took off from bases around Chengdu 47 of which reached and bombed the Imperial Iron and Steel Works at Yahata Japan. This was the first attack on Japanese islands since the Doolittle raid in April 1942.[29] The first B-29 combat losses occurred during this raid, with one B-29 destroyed on the ground by Japanese fighters after an emergency landing in China,[30] one lost to anti-aircraft fire over Yawata, and another, the Stockett's Rocket (after Capt. Marvin M. Stockett, Aircraft Commander) B-29-1-BW 42-6261,[N 5] disappeared after takeoff from Chakulia, India, over the Himalayas (12 KIA, 11 crew and one passenger)(Source: 20th Bomb Group Assn.) This raid, which did little damage to the target, with only one bomb striking the target factory complex,[32] nearly exhausted fuel stocks at the Chengdu B-29 bases, resulting in a slow-down of operations until the fuel stockpiles could be replenished.[33] Starting in July, 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).
The tactic of using aircraft to ram American B-29s was first recorded on the 20 August raid on the steel factories at Yawata. Sergeant Shigeo Nobe of the 4th Sentai intentionally flew his Kawasaki Ki-45 into a B-29; debris from the explosion following this attack severely damaged another B-29, which also went down. Lost were Colonel Robert Clinksale's B-29-10-BW 42-6334 Gertrude C and Captain Ornell Stauffer's B-29-15-BW 42-6368 Calamity Sue, both from the 486th BG.[34] Several B-29s were destroyed in this way over the ensuing months. Although the term "Kamikaze" is often used to refer to the pilots conducting these attacks, the word was not used by the Japanese military.[35][36]
B-29s were withdrawn from airfields in China by the end of January 1945. Throughout this prior period, B-29 raids were also launched from China and India against many other targets throughout Southeast Asia. However, the entire B-29 effort was gradually shifted to the new bases in the Marianas Islands in the Central Pacific, with the last B-29 combat mission from India flown on 29 March 1945.
In addition to the logistic problems associated with operations from China, the B-29 could only reach a limited part of Japan while flying from Chinese bases. The solution to this problem was to capture the Mariana Islands, which would bring target such as Tokyo, about 1,500 mi (2,400 km) north of the Marianas within range of B-29 attacks. It was therefore agreed in December 1943 to seize the Marianas.[37]
Saipan was invaded by US forces on 15 June 1944, and despite a Japanese naval counterattack which led to the Battle of the Philippine Sea and heavy fighting on land, was secured by 9 July.[38] Operations followed against Guam and Tinian, with all three islands secured by August.[39]
Work began at once to construct air bases suitable for the B-29, work beginning even before the end of ground fighting.[38] In all, five major air fields were built, with two on the flat island of Tinian and one on Saipan and two on Guam. Each was large enough to eventually accommodate a bomb wing consisting of four bomb groups, giving a total of 180 B-29s per airfield.[28] These bases, which could be supplied by ship and unlike the bases in China, were not vulnerable to attacks by Japanese ground forces, became the launch sites for the large B-29 raids against Japan in the final year of the war. 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, raids intensified, launched regularly until the end of the war. These attacks succeeded in devastating almost all large Japanese cities (with the exception of Kyoto and several others), and they gravely damaged Japan's war industries. Although less publicly appreciated, the mining of Japanese ports and shipping routes (Operation Starvation) carried out by B-29s from April 1945 significantly affected Japan's ability to support its population and move its troops.
Perhaps the most famous B-29 is the Enola Gay, which dropped the atomic bomb "Little Boy" on Hiroshima on 6 August 1945. Bockscar, another B-29, dropped "Fat Man" on Nagasaki three days later. These two actions, along with the Soviet invasion of Manchuria on 9 August 1945, brought about the Japanese surrender, and the official end of World War II. Both aircraft were handpicked for modification from the assembly line at the Omaha plant that was to become Offutt Air Force Base.
Following the surrender of Japan, V-J Day, B-29s were used for other purposes. A number supplied POWs with food and other necessities by dropping barrels of rations on Japanese POW camps. In September 1945, a long-distance flight was undertaken for public relations purposes: generals Barney M. Giles, Curtis LeMay and Emmett O'Donnell, Jr. piloted three specially modified B-29s from Chitose Air Base in Hokkaidō to Chicago Municipal Airport, continuing to Washington, D.C., the farthest nonstop distance to that date flown by Army Air Forces aircraft and the first-ever nonstop flight from Japan to the U.S.[N 6][41] Two months later, Colonel Clarence S. Irvine commanded another modified B-29, Pacusan Dreamboat, in a world-record-breaking long-distance flight from Guam to Washington, D.C., traveling 7,916 miles (12,740 km) in 35 hours,[42] with a gross takeoff weight of 155,000 pounds (70,000 kg).[43][44]
Although considered for other theaters, and briefly evaluated in England, the B-29 was predominantly used in World War II in the Pacific Theatre. The use of YB-29-BW 41-36393, the so-named Hobo Queen, one of the service test aircraft flown around several British airfields in early 1944, was thought to be as a "disinformation" program intended to deceive the Germans into believing that the B-29 would be deployed to Europe.[18]
Postwar, several RAF Bomber Command squadrons were equipped with B-29s loaned from USAF stocks. The aircraft were known as the Washington B.1 in RAF service, and remained in service from March 1950 until the last were returned in early 1954, having been replaced by initial deliveries of the UKs V bombers.
On three occasions during 1944, individual B-29s made emergency landings in Soviet territory after bombing raids on Japanese Manchuria and Japan. In accordance with Soviet neutrality in the Pacific War, the bombers were interned and kept by the Soviets, despite American requests for their return.[45]
Captain Howard Jarrell and his 10-man crew took off from Chengdu, China, on 31 July 1944 for a mission against the Japanese Showa steel mill in Anshan, Manchuria. Capt. Jarrell's B-29, called "Ramp Tramp",(B-29-5-BW serial number 42-6256)[45] was assigned to the 462nd (Very Heavy) Bomb Group and was part of a large air strike composed of approximately 100 aircraft. At the end of the bomb run, the inboard right engine (No. 3) "ran away" and could not be "feathered" (setting the variable pitched propeller blades parallel to the airflow to minimize aerodynamic drag). So, the engine had to be shut down, which increased the drag of the unfeathered propeller. This made the plane burn more fuel, so it could not get back to Chengdu. The pilot headed toward the Soviet base at Vladivostok, Russia to land the damaged bomber.[45] The crew were allowed to escape into American-occupied Iran in January 1945. The bomber was not returned and instead used in the USSR during 1948-49 as a drop ship for underwing launching of 346P glider, a development of the German DFS 346 rocket-powered aircraft. It was also used by the Soviets in the effort to copy the B-29 as the Tu-4 Bull.[46]
On August 20, 1944 the US Army Air Force B-29 Superfortress "Cait Paomat" (42-93829) flying from Chengdu was damaged by anti-aircraft gunfire during a raid on the Yawata Iron Works. Due to the damage sustained, the crew elected to divert to the Soviet Union. The aircraft crashed in the foothills of Sikhote Alin Range east of Khabarovsk after the crew bailed out. The crew was interned and allowed to escape into American-occupied Iran in January 1945. The airframe was used by the Soviets in the effort to copy the B-29 as the Tu-4 Bull. The complete wing and engines of this aircraft were later incorporated into the sole Tupolev Tu-70 transport aircraft.[46]
On 11 November 1944, during a nighttime raid on Omura on Kyushu Japan, the USAAF B-29 "General H.H. Arnold Special" (42-6365) was damaged and forced to divert to Vladivostok in the Soviet Union. The crew was interned.[46] On 21 November 1944, the USAAF B-29 "Ding Hao" (42-6358) was damaged during a raid on an aircraft factory at Omura, Japan and also forced to divert to Vladivostok. The interned crews were allowed to escape into American-occupied Iran in January 1945. Both B-29s were not returned and instead used in the Tu-4 Bull development effort.[46]
On 29 August 1945, a Soviet Air Force Yak-9 damaged a B-29 dropping supplies to a POW camp in Korea, and forced it to land at Konan (now Hŭngnam), North Korea. The 13-man crew of the B-29 was not injured in the attack, and were released after being interned for 13 days.[47]
The Tupolev OKB dismantled and studied Ramp Tramp and the other two B-29s, and Stalin ordered Tupolev and his design bureau to copy the B-29, and produce a design ready for quantity production as soon as possible. As the supply of aluminum in the USSR was in different thicknesses than available in the US (metric vs imperial),[45] the entire aircraft had to be extensively re-engineered and the Tu-4 cannot be regarded as an exact copy despite external appearances, with Tupolev even substituting his own favored airfoil sections for those used by Boeing.
In 1947, the Soviets debuted both the Tupolev Tu-4 (NATO ASCC code named Bull) copy of the B-29, and the Tupolev Tu-70 transport variant. The Soviets used tail-gunner positions similar to the B-29 in many later bombers and transports.[48]
While the end of World War II caused production of the B-29 to be phased out, with the last example completed by Boeing's Renton factory on 28 May 1946, and with many aircraft sent for storage and ultimately scrapping as surplus to requirements, the remaining B-29s formed the combat equipment of Strategic Air Command when it formed on 21 March 1946.[49] In particular, the "Silverplate" modified aircraft of the 509th Composite Group remained the only aircraft capable of delivering the atomic bomb, and so the unit was involved in the Operation Crossroads series of tests, with B-29 Dave's Dream dropping a "Fat Man"-type bomb in Test Able on 1 July 1946.[49]
The B-29s were outfitted with air filters and monitored debris from above ground nuclear weapons test by the United States and the USSR. The aircraft were also used for long-range weather reconnaissance (WB-29) and for signals intelligence gathering and photographic reconnaissance (RB-29).
The B-29 was used in 1950–53 in the Korean War. At first, the bomber was used in normal strategic day-bombing missions, though North Korea's few strategic targets and industries were quickly reduced to rubble. More importantly, in 1950 numbers of Soviet MiG-15 "Fagot" jet fighters appeared over Korea (an aircraft specifically designed to shoot down the B-29), and after the loss of 28 aircraft, future B-29 raids were restricted to night-only missions, largely in a supply-interdiction role. Over the course of the war, B-29s flew 20,000 sorties and dropped 200,000 tonne (180,000 ton) of bombs. B-29 gunners were credited with shooting down 27 enemy aircraft.[50]
The B-29 was notable for dropping the large "Razon" and "Tarzon" radio-controlled bomb in Korea, mostly for demolishing major bridges, like the ones across the Yalu River and for dams. Also conducted countless leaflet drops in North Korea, such as those for Operation Moolah.[51]
The B-29 was soon made obsolete by the development of the jet engined fighter aircraft. With the arrival of the mammoth Convair B-36, the B-29 was reclassified as a medium bomber with the new Air Force. However, the later B-50 Superfortress variant (which was initially designated B-29D) was good enough to handle auxiliary roles such as air-sea rescue, electronic intelligence gathering, and even air-to-air refueling. The B-50D 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. A total of 3,970 B-29s were built.
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, excluding the Silverplate models built for the Manhattan Project. 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.
An example of a later variant of the B-29, the B-50 Superfortress (which was powered by four 3,500 hp (2,600 kW) Pratt & Whitney R-4360-35 Wasp Major engines), acted as the mothership for experimental parasite fighter aircraft, such as the McDonnell XF-85 Goblin and Republic F-84 Thunderjets as in flight lock on and offs. It was also used to develop the Airborne Early Warning program; it was the ancestor of various modern radar picket aircraft. A B-29 with the original Wright Duplex Cyclone powerplants was used to air-launch the famous Bell X-1 supersonic research rocket plane.
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 and re-designated as KB-29s. 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.
Twenty-two B-29s are preserved at various museums worldwide, including one flying example, along with four complete airframes either in storage or under restoration, eight partial airframes in storage or under restoration and there are four known wreck sites.[52] Only two of the 22 museum aircraft are outside the United States, one is in the American Air Museum at the Imperial War Museum Duxford in the United Kingdom, the other at the KAI Aerospace Museum in Sachon, South Korea.
Notable B-29 accidents and incidents include the 1948 Waycross B-29 crash, which resulted in the United States v. Reynolds lawsuit regarding State Secrets Privilege and an August 1945 accident when two B-29s collided over Weatherford Texas.
Data from Quest for Performance[53]
General characteristics
Performance
Armament
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