Tupolev Tu-4

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Tupolev Tu-4
Tupolev Tu-4 in the Monino Aviation Museum
Tupolev Tu-4 in the Monino Aviation Museum
Type: Strategic bomber
Design country:

Soviet Union 1923Soviet Union Soviet Union

Manufacturer:

OKB Tupolev

First flight:

May 19, 1947

Commissioning:

1948

Production time:

1948-1952

Number of pieces:

847–1296 (depending on the source)

The Tupolev Tu-4 ( Russian Туполев Ту-4 , NATO reporting name : Bull ) was a four-engine long-range bomber of the early days of the Cold War , which in the Soviet Union from the design office Tupolev through replica of the American US Boeing B-29 was realized.

history

In order to find a successor to the hitherto only Soviet heavy bomber Petlyakov Pe-8 , the Soviet Union had already tried unsuccessfully during the Second World War to get modern strategic bombers from the allied USA as part of the loan and lease agreement .

Therefore, in the mid-1940s , the Soviet long-range aviation forces did not have a long-range strategic bomber. In mid-1943, various design offices were given the task of developing a four-engine bomber aircraft similar to the American B-29, which should correspond to the state of American technology. The design department of Iossif Neswal worked on a comprehensively further developed TB-7 , Ilyushin on a four-engine machine called Il-14 (the name was later reused for another aircraft) and Myasishchev on the DBW-202 and DBW-203. From September 1943, Tupolev worked on a prototype named internally aircraft 64. The machine was to be powered by Schwezow-M-71TK-M motors with 2200 hp each, achieve a range of 6000 km with a 8000 kg bomb load, a maximum speed of 500 km / h at a height of 10 km and a maximum internal bomb load of 10 t . A mock-up was completed in September 1944 and approved in April 1945, whereby increased performance parameters, better equipment and other engines (e.g. AM-46TK-3PB) were required for the later production aircraft. Both Tupolev and Stalin realized that it would take several years to develop the required equipment and make the aircraft ready for series production. Thereupon Stalin made the decision in June 1945 to stop all work on the machine and instead to produce an exact copy of the American Boeing B-29. Four American Boeing B-29s that had crashed in Siberia towards the end of the Second World War were kept by the Soviets; these should be used as the basis for your own replica. These were a B-29-5-BW that was damaged by shelling on July 20, 1944 and landed near Vladivostok, a B-29A-1-BN that got lost and crashed near Khabarovsk on August 20, 1944, and a B-29A-1-BN on November 11, 1944 through Japan Flak damaged B-29-15-BW and an emergency landed in the Soviet Union, as well as a B-29-15-BW that reached the Soviet coast on November 21, 1944 after an engine failed and was directed by Russian air forces for an emergency landing on a Russian airfield has been. Under the terms of the Japanese-Soviet Neutrality Pact and the Geneva Conventions , the crews were interned and the machines confiscated. A fifth B-29 that landed in the Soviet Union on August 29, 1945 was returned to the United States, as the Soviet Union had now entered the war against Japan on the side of the United States in accordance with the Treaty of Yalta .

For the replica, it was necessary to transfer the dimensions into the metric system and adapt them to the available materials and engines. For this purpose, the machine, which landed on November 11, 1944 and has since been made airworthy again, was transferred to Moscow on June 23, 1945 and dismantled into all its individual parts, its dimensions removed and the parts rebuilt. All parts were not only measured, but also weighed and photographed. Material analyzes were also carried out for many parts and partial structures (such as electronics) were passed on to a large number of specialized institutes and plants for analysis and reconstruction. In total, the technical production documentation for the machine comprised around 40,000 A4 pages and was completed in March 1946. The replica required great efforts in production, coordination and management. Only about 10% of the materials used for important structural parts were produced in the Soviet Union at that time. The replication of the electronics used, the plastics used and the resistance of some works to the exact replication of American parts instead of the use of Soviet devices also turned out to be a challenge. A replica of the double radial engines Wright R-3350-23 was not necessary because the Schwezow ASch-73TK (a further development of the manufactured under license in 1820 R Wright Cyclone) a suitable drive was available. The IFF system and the defensive armament were also explicitly excluded from the copy, the latter being viewed as too weak in the B-29. The accuracy of the copy was remarkable, as the empty weight of the first replicated machine (35.27 t) differed by less than 1% from the empty weight of the B-29 (34.93 t).

With the first flight on May 19, 1947, the testing of the aircraft, initially designated as the B-4 , began, carried out by pilots M. Gallai , N. Rybko, W. P. Maroonow, A. Wassiltschenko and others and ended in the winter of 1947/48. The first flight itself was carried out as pilot by Nikolai S. Rybko, A. G. Wassiltschenko as copilot and W. N. Saginow as flight engineer. With a take-off mass of 47.7 t, the test showed a maximum speed of 427 km / h at sea level, 543 km / h at 11 km, a rate of climb of 4.6 m / s at sea level, a service ceiling of 11.5 km, as well as a range of 3300 or 6000 km with 9 or 2 t payload. The bombers were shown for the first time in August 1947 during the overflight on flight day in Tuschino . Western observers, however, held the machines for the B-29 that had been made airworthy again. Production took place in plants No. 18 ( Samara ), No. 22 ( Kazan ) and No. 23 (Fili near Moscow).

As defensive armament, NM Afanassjew initially intended to use 12.7 mm machine guns specially developed for this type, but later it was decided to use B-20E cannons. The first three machines built in Kazan received eleven 12.7 mm Beresin UBK machine guns (three in the rear stand). In the later series, the B-20E was replaced by 23mm NR-23 cannons .

In the course of series production, the aircraft was modernized several times and modified for special tasks. This resulted in 20 different versions. In order to be able to accommodate the initially relatively large Soviet atomic bombs , the specially equipped Tu-4A was developed. It differed from the basic Tu-4 by an electrically heated, temperature-stabilized bomb bay, which was equipped with an electronic control. The suspension system for the bulky atomic bomb had to be redesigned and special shielding installed in the pressurized cabins to protect the crew from radiation during the flight. The first ballistic drop tests began in early 1948 with the dropping of dummies of the RDS-1 near Noginsk. The tests with two bombers converted to Tu-4A were completed in 1951 and on October 18, 1951 at 9:52 a.m., the use of such a weapon from an aircraft was tested with this type for the first time in the Soviet Union . During the test, an RDS-3 atomic bomb was dropped from a height of 10 km over Semipalatinsk , which exploded 380 m above the ground. The aircraft was piloted by Captain Konstantin Isaakowitsch Urschunzew and co-pilot Wladimir Semenowitsch Suvorov. To be on the safe side, another Tu-4 with a dummy FAB-1500HE bomb and two Lavochkin La-11s accompanied the Tu-4A to the vicinity of the dropping point. The second Tu-4 was to take the lead if the targeting systems of the plane armed with the atomic bomb should fail. With the help of a series of sound-modulated radio signals to the Tu-4A and the dropping of the dummy bomb, the exact time and place of the drop should be transmitted to it. The Soviet long-distance air forces thus received their first nuclear bomber with the Tu-4A. A total of 18 Tu-4A were built, which from 1952 carried RDS-4 and RDS-5 as series armament. Between 1951 and 1953 another variant was tested with the Tu-4K and Tu-4KS. This was optimized for the use of two KS-1 anti-ship missiles suspended under the wings . In 1955, 300 machines were converted into Tu-4D transport machines for 30 paratroopers and two light armored vehicles in boxes under the wings. From 1956 similarly converted Tu-4Ts were approved for use for up to 42 paratroopers and two to four boxes under the wings. There was also a version converted to the Tu-4R reconnaissance aircraft with AFA-33 aerial cameras, in the front bomb bays of which additional fuel tanks were carried to increase the range and in the rear the camera equipment was carried. When using night cameras NAFA-33S / 50 or NAFA-5S / 100, the tanks could be removed and replaced with light bombs . There were also variants for navigation training, for ECM, ELINT, radiation reconnaissance, communication transmission and as a tanker. Individual machines were also used as test vehicles Tu-4LL (Letajuschtschaja laboratorija, flying laboratory) in various tests such as propeller turbines TW-4 and NK-12 from Kuznetsov and TW-02 from Ivchenko (there as Tu-4TWD ), air refueling systems and radio and radio measuring devices.

In 1952, Tu-4s were stationed at the newly established near-polar air bases in Dikson and on Schmidt Island to shorten the flight distance to North America . Other locations were the Baltic States, Ukraine, Poland and Czechoslovakia. In the GDR, Tu-4s were stationed in Werneuchen in 1955/56 . During the Hungarian People's Uprising , Tu-4s of the 43rd Air Army stationed at Borispol Airfield received orders to bomb the insurgents' headquarters, believed to be in a Budapest theater. On November 3, 1956 at 11:40 p.m., a group of four aircraft, led by Lieutenant Colonel Semyonovich, each carried 3000 kilograms of bombs on board, took off for the flight. The group was ordered to turn back via Romania, as it was feared that their own troops would be accidentally bombed. Two years later, the command aircraft was transferred to the Central Museum of the Air Force of the Russian Federation in Monino, where it has been on view ever since.

KJ-1

Ten machines were donated to the People's Republic of China in 1953 on the occasion of Mao Zedong's sixtieth birthday . There five pieces after the expiration of their time in the 1970s with propeller turbines were fitted WJ-6 and as a test vehicle for drones or AEW - Radom used (as KJ-1) on the fuselage. Two machines of these versions, including the KJ-1, are in the Chinese Aviation Museum in northern Beijing . Overall, China received between 13 and 25 machines (depending on the source).

The series production of the Tu-4 ran out in 1952 after 847 copies (according to other sources based on the production data of the plants up to 1296).

Further developments

Derivatives of the Tu-4 were the Tu-70 passenger aircraft and the Tu-75 transporter . Like these, the further development of the bomber as the Tu-80/85 with more powerful piston engines or propeller turbines did not go into series production.

technology

The Tu-4 was a four-engine, heavy long-range bomber that could be used day and night and also under instrument flight conditions. It was constructed as a self-supporting all-metal middle decker in half-shell construction. The outer skin consisted of D16AT duraluminium plates with a thickness of about 0.8 to 2.0 mm, which were attached to the inner structure by mostly flush rivets. Structurally, the 30.18 m long and maximum 2.9 m wide fuselage consisted of six sections: the glazed nose (section F-1), the front cabin (section F-2, frames 2 to 13), the central fuselage (section F -3, frames 13 to 37), the middle pressure cabin (section F-4, frames 37 to 46), the rear fuselage (section F-5, frames 46 to 57) and the rear fuselage or end section (section F -6, frames 57 to 61), which contained the rear gunner's pressurized cabin. All sections were pre-assembled separately and connected with flanges. The forward and middle pressurized cabins were connected by a pressurized tunnel that ran along the top of Section F-3. Some of the systems and equipment were also housed in the pressurized sections. There were two bomb bays in the central fuselage, which were closed by folding doors and separated by the wing spar box. The forward pressurized cabin accommodated six people: the pilot and co-pilot, the bombardier, the flight engineer, the navigator and the radio operator. In the middle pressurized cabin were the three gunmen who operated the remote-controlled defensive armament and the bomb target radar operator. The glazed nose was made from a dome-shaped casting made from a magnesium alloy . Some panes of glass were made of triplex silicate glass and the rest of plexiglass . In addition, part of the front pressure cabin roof was glazed (again, both silicate and Plexiglas were used), while the middle pressure cabin received three Plexiglas viewing domes (two lateral and one dorsal). The glazing of the rear armament consisted mainly of Plexiglas, with silicate glass panes to the rear. The crew was protected from projectiles and shrapnel by steel plates and bulletproof glass. The pilots were protected by bullet-proof panes of glass, front armor plates, armored seat backs and folding back armor plates. The gunner and the radar operator in the central cabin were protected by an armored door and an armored box containing the weapon control systems, while the rear gunner was protected by a steel plate and bulletproof panes of glass.

The trapezoidal, non-swept and two-spar wings had an aspect ratio of 11.5 and a profile similar to the RAF-34. They were made in three sections (middle part and one outer wing each). The middle section consisted of 32 ribs and 24 stringers, the duralumin paneling of which varied in thickness between 1.0 and 2.5 mm in the lower part and 4 to 5 mm in the upper part. The middle section also contained the engines, the main landing gear and the integral tanks (22 flexible tanks with a total capacity of 20,180 liters). For long-range missions, three additional fuel tanks with a capacity of 2,420 liters could be installed in the front bomb bay. Each outer wing consisted of four parts - the torsion box, a removable leading edge, a removable front fairing, and an aileron with trim tabs. In addition, they housed slotted flaps over the entire trailing edge of the wing center section, which were set at 25 ° for take-off and 45 ° for landing. The rudder and horizontal stabilizer had rubber leading edges for de-icing. The three-part electrically retractable landing gear was equipped with twin tires (1,450 mm × 520 mm main landing gear and 950 mm × 350 mm nose wheel) and had a track width of 8.68 m and a wheelbase of 10.44 m. The main landing gear was pulled forward into the inner engine nacelle and had hydraulic brakes (56-70 bar) and shock absorbers. At the stern there was an extendable spur to protect it from touching down.

The engines used were four air-cooled 18-cylinder double radial engines of the Schwezow ASch-73TK type with a two-stage charger ( turbocharger with intercooler + fan), the 2,400 hp (1.8 MW) at 2,600 rpm at start and 2,000 hp 1.5 MW) delivered nominal power at 2,400 rpm in cruise flight. The motors are each connected via a planetary gear with a ratio of 0.375 to the V3-A3 or V3B-A5 four-blade propellers with a diameter of 5.06 m. Each engine is 2.29 m long, 1.37 m in diameter and weighs 1,339 kg when dry. The specific fuel consumption is 350 g / PS h (476 g / kW h) at take-off power and 315–335 g / PS h (428–455 g / kW h) at nominal power. Each motor was attached to a carrier via nine vibration dampers, which in turn was attached to six points on the nacelle structure. There are several electrically operated flaps on the rear edge of each bonnet to control the flow of cooling air. Each engine has its own oil system with an oil cooler in the respective engine nacelle, which was supplied by five bag oil tanks (four main tanks and one auxiliary tank) with a total of 1,540 liters. The motors themselves, but also the tail units and trim rudder, were controlled without amplification by means of cables and pulleys.

In section F-5 there was the M-10, a 10 HP motor for electrical supply in an emergency. More than 150 electrical servo systems were installed in the Tu-4, which were operated with 28 V (26 V / 400 Hz and 115 V / 400 Hz via converters for special systems). The power supply was provided by six motor-driven 9-kilowatt generators GS-9000M or GSR-9000 (two on each outer motor and one on each inner motor) or as backup 12A-30 silver-zinc batteries (28 V, 30 Ah) and a 5 kW generator GS-5000, powered by the M-10 APU. Depending on the bomb racks installed in the bomb bays, the Tu-4 could hold up to 48 FAB-50 or FAB-100, 40 FAB-250M46, 24 FAB-250M43 or FAB-250M44, 12 FAB-500M43 / 44/46, 8 FAB-1000M44 or FAB-1500M44 / 46, 4 FAB-3000M44 / 46 or 2 FAB-6000M46- free -fall bombs with a maximum weapon load of 12 t and dropped in volleys of 1, 2, 4 or all. Bombs with chemical warfare agents ChAB-500-280S M-46 and ChAB-250-150S or other special bombs could also be used. The cobalt radar derived from the American AN / APQ-13 enabled the targeted dropping of bombs at night and in bad weather from heights of over 3000 m. It was able to discover larger industrial plants at a distance of about 100 km, with a directional accuracy of 2 ° and a distance accuracy of 100 m.

operator

Technical specifications

Parameter Data
crew 9-10
length 30.19 m
span 43.08 m
height 8.46 m
Wing area 161.70 m²
Wing extension 11.5
Wing loading 379.5 kg / m²
Power load 6.6 kg / hp
Preparation mass 35,270 kg
Takeoff mass normal 47,500 kg
maximum 66,000 kg
Top speed 420 km / h near the ground
558 km / h at an altitude of 10,000 m
Service ceiling 11,200 m
Range 5,100 km with 2,000 kg bombs
Engines four 18-cylinder twin star engines Schwezow ASch-73TK with 2,400 hp (1,765 kW) each
Armament five turrets with four twin and one triple cannon B-20E (20 mm) or five twin cannons NR-23 (23 mm) and a total of 3150 rounds,
up to 12,000 kg bombs

See also

literature

Web links

Commons : Tupolev Tu-4  - collection of pictures, videos and audio files

Individual evidence

  1. Vladimir Kotelnikow: Tupolew Tu-4 (2nd part) . In: Aviation Classics . No. 4/2015 . Motor Presse, Stuttgart, p. 27 .
  2. a b c d e f g h i j Jefim Gordon , Dmitri Komissarow, Wladimir Rigmant: Tupolev Tu-4: The First Soviet Strategic Bomber . Schiffer Publishing, Limited, 2014, ISBN 978-0-7643-4797-9 , pp. 6 ( limited preview in Google Book search).
  3. a b c d FliegerRevue 8/2017, Tupolew Tu-4 bomber , pp. 48–53
  4. Сергей Кремлев: Берия. Лучший менеджер XX века . Litres, 2017, ISBN 5-04-043370-0 ( limited preview in Google Book Search).
  5. wikireading.ru: 10. Первое воздушное испытание атомной бомбы 18 октября 1951 г .. Авиация и ядерные испытания , accessed on July 17, 2017.
  6. Rainer Göpfert: “Maria” and “Tatjana” - The testing of nuclear weapons by the air forces of the USSR . In: Flieger Revue Extra . No. 36 . PPVMedien, 2012, ISSN  2194-2641 , p. 11 .
  7. Jewgeni Podolny, Ulrich Unger: Your goal is Budapest . In: Fliegerrevue . No. 3/96 , p. 35-37 .
  8. ^ Andreas Rupprecht: AWACS in Chinese. Early warning programs beyond the great wall . In: Fliegerrevue . No. 01/2010 , p. 28 .
  9. Chinese Nuclear Forces: Tu-4 BULL , accessed July 17, 2017.
  10. Paul Duffy, AI Kandalov: Tupolev The Man and His Aircraft . SAE, 1996, ISBN 978-1-56091-899-8 , pp. 93 ( limited preview in Google Book search).
  11. ^ Walter J. Boyne: Air Warfare An International Encyclopedia . ABC-CLIO, 2002, ISBN 978-1-57607-345-2 , pp. 636 ( limited preview in Google Book search).
  12. Pavel Podvig, Frank van Hippel: Russian Strategic Nuclear Forces . Massachusetts Institute of Technology, Cambridge 2001, p. 367 (English).