Tu-4 Variants

Tu-4 (a copy of the American Boeing b-29 bomber) is widely known as the first Soviet post-war strategic bomber. Its development played an important role in raising the General level of domestic aviation industry and largely drafted a qualitative leap that is associated with the creation of a new generation of bombers, Tu-95 and TU-1B. Tu-4 had numerous standard and advanced versions. Along with those embodied in metal versions, there were projects that remained on paper, but rather a curious and original. The 474 and 485 Projects were a development of Tu-4 featuring six [versus four] ASh-73TK engines, a wing span of 56 meters, and a take-off weight of 95 tons. This concept did not proceed beyond the design stage.

The TU-12 (also designated the TU-70) is a passenger aircraft. Prototype. Built on the basis of B-29 components, used a new pressurized fuselage designed for 72 passengers. First flight - 27 November 1946. The aircraft was successfully tested, was recommended to serial production, but was not produced in series because Aircraft Industry Plants were overloaded with military orders and Civil Air Fleet was not ready to operate the aircraft of such class.

The TU-16 (also designated the TU-20, TU-75) is a military transport a/c. Prototype. Built on the basis of TU-4 components, new fuselage designed for transportation and descending cargo, people and equipment. The first native machine of this class; is equipped with rear fuselage ramp hatch. Was tested. First flight -21 January, 1950. Was not put into serial production because Air Force was not ready to accept such a machine.

Immediately after initial serial production of the Tu-4 began, work started to adapt the bomber to strike at American territory. Some airplanes were outfitted to carry nuclear bombs and were designated as TU-4A. During re-equipment, the bomber was outfitted with a thermostatically controlled heated bomb bay, a suspension unit for the bomb was developed, and biological protection devices for the crew were supplied. Some TU-4 bombers were equipped with aerial refueling devices, and scant few were outfitted with additional fuel tanks located under the wings. They were deployed in 1952, though the majority of the TU-4s were not re-equipped with air refueling. Although the limited range of the Tu-4 rendered it incapable of striking the United States and subsequently returning to bases in the Soviet Union, neither country was a stranger to one-way strategic bombardment missions, given the precedent of the FRANTIC operations in World War II.

In 1948, work on the "Comet" missile project began. The modified version of the Tu-4 bomber - the TU-4K - was supposed to be equipped with two KS-1 air to surface missiles and the "Comet-1"/"Comet-2" guidance system. The first TU-4K prototype was finished in 1951, with production testing in 1951 and 1952. Between July 1952 and January 1953 the bomber was tested, and subsequently deployed with naval aviation. In 1950 OKB Tupolev studied the possibility of equipping the TU-4 with the turbo-prop engines of the TB-2 aircraft. But the flight performance was only increased by 14-20 percent, and the project did not proceed into development. The "Burlak" weapon system was developed in the early 1950s to protect the bomber from attacks. The TU-4 bomber towed a pair of MIG-15 fighters as an escort. However, after proving that this was technically feasible, the project was cancelled. Some TU-4s were converted into secret command centers and though designed primarily as a bomber, the Tu-4 could also be equipped for reconnaissance missions.

In 1950, the head of the 2nd Branches of the scientific and technical division of NII VVS [Air Force Scientific and Technical Institute] major L. Martynenko and Chief Engineer of the scientific and technical division of NII VVS engineer Captain D.m. Ruter made an unusual proposal to create in the short term a domestic long-range bombers weighing 120-130 tons. To this end, they proposed to build an aircraft composed of two Tu-4. This aircraft was by removing two Tu-4 wings and docking of aircraft between the ends of the wing.

This is how the authors justify its proposal. Application of dual plane would reduce the number of cabin crew from 22 people (for two Tu-4) up to 13-14 people and remove a number of units of armament and equipment (some turrets, radar, etc.) are not required in the dual number. This could increase the weight of fuel and bombs. Increased elongation of the wing would enhance its aerodynamics. Application of the double hull would use more economical engines. All this, according to the authors, was supposed to provide a significant increase in the aircraft's dual speed and range over the original Tu-4.

Martynenko and Ruter estimated the maximum technical range when bomb load of 3000 kg increased at a height of 3000 m-6380 km up to 11000 km (73%); at a height of 8000 m-5050 km to 9450 km (87%). Application of refueling in flight could increase the range of up to 13000 km (at additional charge) and up to 16000 km (with two refuelling exercises).

It was assumed that maximum speed at an altitude of over 10000 m will rise from 545 km/h up to 610 km/h (at nominal regime). Particularly impressive was the promise of the sponsors of the proposal to enhance the bomb load. At maximum 5000 km range technical at a height of 8000 m it increased with 6000 kg (for 2-4) to 23500 kg (at 292%).

According to Martynenko and Ruter, dual-mass production of aircraft Tu-4 could be launched in a few months, and with the increased attention to this issue in a few weeks. Newly projected bomber aircraft with new engines, they noted, the AIR FORCE will be able to do enough in just a few years, and before that time the aircraft would be the best solution, a dual. At the end of his letter, the authors of the proposal wrote: "Aerobatic aircraft according to the dual property of test pilot Colonel grade 1 Nûhtikova are acceptable.

The proposal, dated July 1, 1950, was submitted to the Secretary of the CPSU (b) Malenkovu G.m. and brought to the attention of the Ministry and the air force leadership. (RSAE f. 8044.1 d. 2125 pp. 222-224).

Minaviaprom, in turn, sought the opinion of A.n. Tupolev, whose opinion was negative. He pointed out that the connection of two Tu-4 end spans of strength is not valid. In addition, the proposed dual plane will be bulky and very complex to operate the aircraft, which will be extremely difficult for the crew, because the need to centralize management of motors, control units, aircraft armament, equipment, etc.

The connection of the two planes, said Tupolev, will also require a radical transformation of a number of major parts of aircraft Tu-4. For example, you need to install a new chassis, increasing the area of ailerons, the introduction of a link between the tails of planes and a number of other changes. Thus, the proposed connection aircraft cannot be performed by small alterations of serial aircraft, required indigenous alterations are not feasible because of the complexity and the cumbersome dual aircraft.

He also noted that the alleged authors of the data to increase the range, speed and bomb load for a pair of Tu-4 clearly overstated and some characteristics of coaxial Jet would deteriorate considerably compared with existing aircraft.

This is the conclusion of the Tupolev was brought to the attention of the Deputy Chairman of the USSR Council of Ministers N. Bulganina. (RSAE f. 8044.1.2125l. 225). In the end, the idea of a "dual" Tu-4 was not accepted for implementation.

Although the Soviets phased it out as an operational bomber, it was used for this purpose for some years thereafter in the Chinese Air Force. From the early 1960s on, the TU-4 were only used as transport aircraft, training aircraft and flying airforce laboratories.

In 1955 some 300 TU-4 aircraft were converted to the transport aircraft TU-4D configuration, which remained in operational service through the mid-1960s. This modification was adapted to transport and airdrop 28 paratroopers with their equipment. Despite this outfitting, the aircraft bomber retained its long-range bombing capabilities. In 1956, the TU-4 was experimentally converted into a troop carrying aircraft (TU-4T). The TU-4 served as the basis for the passenger plane TU-70 and the military transport aircraft TU-75. In the early 1960s, a total of six Tu-4 were converted into flying laboratories (TU-4LL) to support testing of piston, turbo-prop and turbojet engines. In the late 1950s some aircraft were converted to the TU-4USHS trainer.