| B-29 Superfortress | |
|---|---|
 Boeing B-29 assigned to B-29 Transition Training School,Maxwell Field,Alabama | |
| General information | |
| Type | Strategic bomber |
| Manufacturer | Boeing |
| Status | Retired (seeSurviving aircraft) |
| Primary users | United States Army Air Forces |
| Number built | 3,960 |
| History | |
| Manufactured | 1943–1946[1] |
| Introduction date | 8 May 1944 |
| First flight | 21 September 1942[2] |
| Retired | 21 June 1960 |
| Variants | All models Boeing KB-29 Superfortress XB-39 Superfortress Boeing XB-44 Superfortress Boeing B-50 Superfortress |
| Developed into | Boeing 377 Stratocruiser Tupolev Tu-4 |
TheBoeing B-29 Superfortress is aUnited States Army Air Forces long range, strategic heavy bomber that was produced in manyexperimental and production models from 1943 to 1946.
TheXB-29, Boeing Model 345, was the first acceptedprototype or experimental model delivered to theArmy Air Corps, incorporating a number of improvements on the design originally submitted, including more and larger guns andself-sealing fuel tanks. Two aircraft were ordered in August 1940, and a third was ordered in December. Amockup was completed in the spring of 1941, and it first flew on September 21, 1942.
Testing was conducted on the XB-29 until February 18, 1943, when the second prototype crashed. The flight was conducted byBoeing's chief test pilot,Edmund T. "Eddie" Allen on a two-hourpowerplant performance test. The accident happened when leaking fuel from a filler cap in the wing leading edge ran down inside the leading-edge and ignited. The fire spread to the engines, and due to the much reduced power, the aircraft, unable to climb, crashed into the Frye meat-packing plant. The crash demolished the majority of the packing plant and killed all eleven XB-29 crew, 22 employees at the plant, and one fireman.[4] Many leading Boeing personnel involved in the design perished in the accident; the pilot, Allen, was chief of the Research Division. After the crash, theUnited States Army Air Forces and acongressional committee headed by then-SenatorHarry S. Truman investigated the B-29 program, issuing a scathing report, prompting the Army Air Forces to take control of the program.
TheYB-29 was an improved XB-29 and 14 were built for service testing. Testing began in the summer of 1943, and dozens of modifications were made to the planes. The engines were upgraded fromWright R-3350-13s to R-3350-21s. Where the XB-29 had three-bladed props, the YB-29 had four-bladed propellers. Various alternatives to the remote-controlled defensive systems were tested on a number of them, particularly the fourth one delivered. After alternative arrangements had been fully tested, defensive armament was standardised at ten .50-calibre machine guns in turret-mounted pairs. The YB-29 also featured a betterfire control system.[5]
TheB-29 was the original production version of the Superfortress. Since the new bomber was urgently needed, the production design was developed in tandem with the service testing. In fact, the first B-29 was completed only two months after the delivery of the first YB-29. Forty-six B-29s of this variant, built by theGlenn L. Martin Company at itsOmaha plant, were used as the aircraft for theatomic bomb missions, modified toSilverplate specifications.
Some 2,513 B-29s were manufactured by Boeing-Wichita (1,620), Bell-Atlanta (357), and Martin-Omaha (536).[6]
TheB-29A was an improved version of the original B-29 production model. This is the definitive wartime variant of the B-29. All 1,119 B-29A's were built at theBoeing plant inRenton, Washington, formerly used by theUnited States Navy.
Enhancements made in the B-29A included a better wing design and defensive modifications. Due to a demonstrated weakness to head-on fighter attacks, the number of machine guns in the forward dorsal turrets was doubled to four beginning with production block 20. Where the wings of previous models had been made by the sub-assembly of two sections, the B-29A wing was built up from three. This made construction easier, and increased the strength of the airframe. The B-29A was produced until May 1946, when the last aircraft was completed. It was employed up to, and through, theKorean War, after which it was then quickly phased out when theB-47 Stratojet became operational.
Washington B Mk 1 – This was the service name given to 88 B-29As supplied to theRoyal Air Force.
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TheB-29B was a modification used for low-level raids, designed with the intent offirebombingJapan. Since fighter opposition was minimal over Japan in late 1944, many of the Army Air Force leadership — most notablyCurtis LeMay, commander of theXXI Bomber Command — felt that a (lighter) faster bomber would better evade Japaneseflak.
In the B-29B, as with the atomic raid-dedicatedSilverplate versions earlier, all defensive armament was removed except for that in the tail turret. Initially the armament was two .50 inAN/M2 machine guns and one 20 mmM2 cannon which was soon changed to three .50 in AN/M2s. The weight saved by removing the guns increased the top speed from 357 mph to 364 mph (575 km/h to 586 km/h).
Also incorporated on this version was an improvedAPQ-7 "Eagle" bombing-through-overcast radar that was fitted in an airfoil-shaped radome under the fuselage.[10]
All 311 B-29Bs were built at theBell plant inMarietta, Georgia ("Bell-Atlanta").
TheB-29C was a modification of the B-29A re-engined with improvedWright R-3350 Duplex-Cyclone engines. The Army Air Force originally ordered 5,000, but cancelled its request whenWorld War II ended and none were built.[11]
TheB-29D was an improved version of the original B-29 design, featuring 28-cylinderPratt & Whitney R-4360-35Wasp Major engines of 3500 hp (2600 kW) each — nearly 60% more powerful than the usualDuplex-Cyclone. It also had a taller vertical stabilizer and a strengthened wing. TheXB-44 was the testbed designation for the D model.
WhenWorld War II ended, the B-29D was given the quartet of Wasp Major engines to become theB-50, which served throughout the 1950s in the U.S. bomber fleet.
A number of B-29s were converted to serve as test beds for new systems. These all received variant designation, even though many existed only as a single converted aircraft.
TheXB-29E forfire-control systems (one converted) was a model B-29-45-BW.[13]
TheB-29F for cold-weather operation inAlaska were six converted B-29-BWs.[14]
The B-29 was used in the development ofjet engines. Stripped of armament, a converted B-29B-55-BA[15] (44-84043)(Bell) designated theXB-29G carried experimentaljet engines in its bomb bay, which were extended into the airstream for testing during flight. This plane was used to test theAllison J35,General Electric J47 andJ73 jet engines.[16]
TheXB-29H to test armament configurations was a converted B-29A.[17]
Experimentation in piston engines continued. Six B-29s (redesignatedYB-29J)[18] of various designation were upgraded to R-3350-79 engines. Other engine-associated items were also upgraded, including newCurtisspropellers, and 'Andy Gump' cowlings, in which the oil coolers have separate air intakes. Two were later converted to aerial refueling tanker prototypes, and redesignatedYKB-29J. The remainder were used forreconnaissance, and designatedRB-29J.
TheEB-29 (E stands for exempt), was used as a carrier aircraft in which the bomb bay was modified to accept and launch experimental aircraft. They were converted in the years followingWorld War II. One EB-29 was converted to carry the famousBell X-1 until it was replaced by aB-50. Another was used to carry and test theXF-85 'parasite fighter'. This fighter was intended to be carried by theConvair B-36 on long-range missions to protect it fromSoviet fighters. Another EB-29 was used to carry twoEF-84B Thunderjet fighters as part ofProject Tom-Tom. All three Tom-Tom aircraft (the B-29 and the two jet fighters) and their crews were lost in a crash on April 24, 1953.[20]
EarlyB-29/B-29As that were modified for photo reconnaissance carried theF-13/F-13A designations, with "F" meaning 'photo'. The aircraft (118 modified B-29BWs and B-29As) carried three K-17B, two K-22 and one K-18 cameras. Between the end of World War II (1945) and 1948 the designation was changed toFB-29J. In 1948, theF-13/FB-29s were redesignatedRB-29 andRB-29A.
SixB-29A/F-13As were modified with the Wright R-3350-CA-2 fuel injected engines and designated atYB-29Js. These were then converted toRB-29Js.[22]
In January 1949, RB-29s were assigned to the91st Strategic Reconnaissance Wing and moved toYokota AB, Japan in December 1950; to provide support to the Korean War and attached to the15th Air Force,Far East Air Force.
TheSB-29 'Super Dumbo' was a version of the B-29 adapted forair-sea rescue duty afterWorld War II. Sixteen B-29s were modified to carry a droppableA-3 lifeboat under the fuselage; redesignated SB-29, they were used mainly as rescue support for air units that flew long distances over water. The first SB-29s were received by theAir Rescue Service in February 1947. With the exception of the forward lower gun turret, all defensive armament was retained; the aircraft additionally carried a variety of radio equipment, provisions,survival kits, and extracrew. The SB-29 was used operationally throughout theKorean War into the mid-1950s. It received its nickname fromDumbo, the Disney character, whose name was given to theaircraft used in previous missions to pick airmen up when they crashed at sea.
TheTB-29 was a trainer conversion of B-29 used to train crew for bombing missions; some were also used to tow targets, and the designation included B-29s modified solely for that purpose. Their most important role was serving as radar targets in the 1950s when theUnited States Air Force was developing intercept tactics for its fighters.
TheWB-29s were production aircraft modified to perform weather monitoring missions. An observation position was fitted above the central fuselage section. They conducted standard data-gathering flights, including from theUK over the Atlantic. They were also used to fly into the eye of ahurricane ortyphoon to gather information. Following nuclear weapons tests, some WB-29s used air sampling scoops to test radiation levels. On 3 September 1949, a WB-29 returning fromYokota AB, Japan, toEielson AFB, Alaska, recovered radioactive debris in air sampling scoops from the cloud generated by thefirst atomic bomb test by the Soviet Union on 29 August.[23]
In 1951, three B-29s were modified for use in theAirborne Early Warning program. The upper section of the forward fuselage was extensively modified to house anAN/APS-20C search radar, and the interior was modified to house radar andElectronic Counter Measures (ECM) equipment. This development led to production radar picket aircraft, including theEC-121 Warning Star. (×3, converted)
A Soviet-built copy of the B-29, theTu-4, was used as the platform for a Chinese experimental airborne early warning aircraft, theKJ-1 AEWC, in the 1970s.
A study for the conversion of B-29s to long-rangecruise missiles was conducted by theAir Materiel Command between 1946 and 1950; given the designation MX-767, it was given the codename Project Banshee. Flight tests were conducted, however no full conversions were carried out before the project was abandoned.[24]
TheU.S. Navy acquired four B-29-BWs from theU.S. Army Air Forces on March 14, 1947. These aircraft were modified for long-range patrol missions and given the designation P2B-1S with NavyBureau Numbers (BuNo) 84028, 84029, 84030 and 84031.
BuNo 84029, previously AAF Ser. No. 45-21787,[26] was modified to carry the Navy'sDouglasD-558-2 Skyrocket high-speed research aircraft. Thebomb bay was modified to carry the Skyrocket II under the belly and drop for supersonic speed testing. The first Skyrocket test flight occurred on September 8, 1950, with test pilot William B. Bridgeman, and George Jansen flying the B-29.Scott Crossfield later broke Mach 2 flying the Skyrocket on November 20, 1953; the last Skyrocket flight was in December 1956.
The P2B-1S "mother-ship" was nicknamedFertile Myrtle and was assigned theNACA number 137. As of May 2013, this aircraft was in the collection ofKermit Weeks at hisFantasy of Flight aviation museum inPolk City, Florida. The forward fuselage section was restored and briefly displayed at theFlorida Air Museum inLakeland, Florida. It has since been relocated to Fantasy of Flight's "Golden Hill" storage facility along with the remainder of the disassembled aircraft, awaiting future restoration to flyable status.[27][28]
BuNo 84030 and 84031 were later modified into anti-submarine patrol bombers and redesignated P2B-2S.[29]
TheXB-39 Superfortress was a singleYB-29 modified to use water-cooledAllison V-3420-17 Vee type engines. Since the Army Air Force was concerned that problems might develop with their first choice of engine, theWright R-3350, they contractedGeneral Motors to test a modified aircraft to show that it could still be used if the R-3350 development was not successful. Since the R-3350 did not have significant enough problems to prevent its use, no XB-39s were ordered.
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In 1945, three B-29s were forced to land inSoviet territory after a bombing raid on Japan because of lack of fuel. Since the Soviet Union was not at war with Japan at the time, the aircraft and crew were interned. Eventually, the B-29 crew members were returned, but the aircraft remained in Russian hands. Seeking a modern long-range bomber,Joseph Stalin ordered theTupolevOKB to reverse-engineer the Superfortress.
The resulting aircraft first flew on May 19, 1947, and immediately began series production, totalling 847 Tu-4s. Although largely identical in appearance to American B-29s, the Tu-4 (NATO reporting name: "Bull") had Soviet-designed defensive guns and had been re-engineered to suit production using material ofmetric thicknesses, resulting in an aircraft that was slightly heavier and slower than the B-29. The Tu-4 presented a significant leap forward in Soviet strategic bombing. Not only did theSoviet Air Forces have the means to deliver nuclear weapons, but the Tu-4 had sufficient range to reach the United States on a one-way trip. On October 18, 1951, a Tu-4 was used in the first air-drop test of a Sovietatomic bomb.
The Tu-4 had been phased out of Soviet service by the early 1960s, being replaced by more modern aircraft such as theTupolev Tu-95. Although the Tu-4 had never delivered any explosive payload with offensive intent, it influenced Soviet aircraft technology, particularly airframe construction and onboard systems. Advanced transport and bomber variants of the Tu-4 design such as theTu-70,Tu-75,Tu-80, andTu-85, were developed and built, but none of these achieved series production.
ThePeople's Liberation Army Air Force ofChina attempted to use the Tu-4 airframe in theKJ-1AWACS aircraft.[31]