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TU-91 Bychok / Boot

The TU-91 was a naval multi-purpose strike aircraft - diving bomber, torpedo-carrier, land-based attack aircraft. The Tu-91 had a powerful turboprop in the mid fuselage, behind the cockpit, with split exhausts behind the wing roots. It had a big three-bladed contra-rotating propeller. It had straight wings, but slightly swept tail surfaces. Characterized by quite original arrangement of powerplant (engine installed behind cockpit, torque moment transfer to two coaxial propellers), for the time it was a powerful offensive weapon, improved armor structure and enhanced performance.

The prototype was initially was designed as a carrier-based aircraft. After a first flight on 02 September 1954, the aircraft successfully passed plant and combined tests, and was recommended for serial production, preparation for which had been already begun. The second copy of the machine was built which was going to become a standard for the serial production, training and anti-submarine versions were tried out. But by a number of subjective and objective reasons the TU-91 was removed from production and all work on this aircraft were terminated.

At the beginning of the 1950s the military-political management of the USSR raised a question about the creation of the domestic aircraft carriers of different designations. In parallel with the creation of aircraft carriers it was planned to develop carrier-based fighters, attack aircraft and bombers. Development of deck bombers and attack aircraft was charged to the design OKB A.N. Tupolev. At OKB Tupolev there was at this time little theoretical understanding of the design of carrier-based heavy aircraft.

In 1950, in a team of OKB projects led by B. Kondorski, preliminary exploration work began on two projects of flight deck aircraft: a single-engine torpedo bomber "507" with a theater and a torpedo bomber-509 project for two turbojets. Tupolev was given the task of designing a strike aircraft for the new fleet. Tupolev asked two of his teams to prepare design proposals. One of these, Project '509' (1950 ninth project) was a Tu-l4 version, essentially taking a Tu-l4T and equipping it with folding wings (for below deck storage), an arrestor hook and boosters.

The task for the project "509" provided for the exploration of the possibility of creating a deck torpedo bomber with two VK-1 engines with the following parameters: crew - 2 people, maximum speed of flight km/h at an altitude of 5000 m, take-offs with two accelerators in the course of the ship 20 knots, range of km at 1500 kg load. Rifle and cannon armament was fixed forward - two caliber guns 23 mm and back - two guns of 23 mm caliber in the stern remote installation. Dimensions of the aircraft with a folded wing - a height of 6 m, a span of 8 m and a length of 15 m. In the course of the studies, the possibility of linking the "509" aircraft on the basis of the projects of the front-line bomber OKB "81" and "82" was considered.

By October 1950, prepared proposals for a twin-engine deck aircraft with a direct folding wing of 54 square meters. Although the designers succeeded in meeting the specified dimensions and requirements, there were difficulties when placing a stern remotely controlled installation on the airplane with the Argon aiming radar, as well as with the fulfillment of the requirements for the take-off length, which was provided only with the use of four launch accelerators. Proposals for the "509" aircraft were not further developed, and all efforts were focused on the aircraft for the theater, which promised fewer problems in the takeoff and landing modes.

Tupolev Samolyet 509 In late 1950-early 1951, when the USSR was still thinking about the creation of aircraft carriers, there was an unwillingness to develop suitable aircraft for them. Andrei Nicolaevich suggested that the OKB consider two ways to find a universal aircraft suitable for aviation Navy, and for the Air Force, and for the army on the basis of twin turbojet. The main difficulty was to find the idea of the layout. The twin-motored by plane (Project 509) was engaged by I.B.Babin, single-engine- theater aircraft (the future Tu-91) by A.A.Yudin.

The OKB, computing, evaluated comparative data of the layout options. For twin aircraft there were difficulties in the layout of the efficient mechanization of the wing in conjunction with its folding (Reduction of dimensions to be placed on the aircraft carrier). Then the designers began to familiarize with ideas and ways of realization of blowing on the flaps, then the most detailed plan began to emerge.

When A.N. Tupolev appeared an idea to make such a flap based on the modification of Tu-124 (Tu-124a) aircraft, its implementation for the study of blow on the flaps was carried out by a flying laboratory Tu-11OLL. While this work was ongoing, the question of creating aircraft carriers was decided in the negative. The Air Force took the IL-28, the Navy the Tu-14. As a result, the Project 509 quietly ended.

The Tu-91 multi-purpose (dive bomber, naval, Attack) single-engine aircraft differed by the original layout of the power installation, powerful offensive armament, and high flight data. The first flight was performed on September 2, 1954. (test pilot D. V. Zyuzin) and was recommended in the series. However, the Leadership of the USSR decided not to create aircraft carriers which led to the cessation of works on Tu-91, although a second copy of the aircraft was built, successfully passing the necessary tests.

According to project the aircraft "509" had to be flight vehicle with two TRD (turbojet engine) of the type VK-1, similar to the assembly solutions to the Tupolev's aircraft "81" (Tu-14) and "82". The wing of the aircraft was intended be straight, which would fold on the deck of the ship. The takeoff of the aircraft, whose mass was 15 t, had to be produced with the aid of the accelerator with the speed of running of the aircraft carrier of 20 knots. Takeoff with the aid of a catapult was not provided for. Work on the deck torpedo bomber- bomber "509" did not leave the stage of preliminary design, since the entire attention of the customer gradually switched to the project of OKB - aircraft "507" (seventh project 1950 g.), work on which in parallel was conducted in the brigade of B.M.Kondorskogo.

The project 507 dealt with a deck torpedo bomber- bomber, attack aircraft with a single TV-2F turboprop engine with a power of 6250 e.hp. In the course of design in 1952 the OKB examined the design of the aircraft of the class of the machine "507", but with a TV-12 with a power of 12000 e. hp and a wing with a sweep angle on quarter-chords of 35. The Aircraft had to, according to the calculations, fly at a speed of approximately 1000 km/h and into some of degree become competitor the carrier-based fighter, which was being worked on at OKB A.S. Yakovlev, preserving in this case the bomber-assault possibilities of project "507". The discussion dealt with the creation of a universal carrier-based aircraft of the type of fighter-bomber, capable of executing the wide circle of the tasks, laid on the carrier-based aircraft. Overall sizes and mass of a similar aircraft had to be more than analogous, given to project "507", because of the considerably larger mass of power plant. Work along this aircraft did not leave the stage of technical proposal, and later a similar version was not evaluated.

Stalin died on 05 March 1953 and the operational need for the Tu-91 disappeared after Stalin's death, when the ship-building program was cut back and the carriers cancelled. At the beginning 1953 the interest in aircraft carriers in the USSR decreased, and naval aviation changed its requirements for the aircraft. Now the discussion dealt with the creation of the purely land-based combat flight vehicle, intended for action in the coastal theaters of military actions. On June 1, 1953. the command of aviation Navy gave out operational requirements for the torpedo dive bomber with one TV-2m engine. For chief designer on the design of the aircraft "91" (precisely this final designation on OKB obtains new machine) A.N.Tupolev appointed V.A.Chizhevskogo, who had worked in OKB A.N. Tupolev and had large experience of designing attack aircraft with piston power plants.

According to the decision of government aircraft "91" was intended for dive bombing ships, Naval bases and coast construction; torpedoing combat ships and transports; and as an additional task: assault actions on the ships, the transports, the landing facilities and the personnel of landing, and also level bombing. Aircraft "91" had to carry out takeoffs and landings in the daytime and at night, also, in the adverse weather conditions from the unpaved airfields and the airfields with the limited runways. The fulfillment of combat missions in putting of torpedo and bomb attacks, and also assault actions it had to be achieved both by the single aircraft and in the composition of group under the conditions of the strong opposition to antiaircraft artillery of enemy.

The chief characteristic of aircraft was use of the TV-2M engine (with equivalent horsepower 6250 e. hp, with plans to bring it in the future to 7650 e. hp). The reduction gearing was set into rotation with the aid of the long shaft, passing through the flight deck between the seats of the pilot and navigator. The reducer revolved two coaxial propellers, that were rotating in opposite directions. Air intake to the engine was made from the front from below. Exhaust gases were directed to the sides on the sides of the fuselage through the double exhaust nozzle.

The prototype of the TV-2f engine was designed and built in OKB-276 N.D.Kuznetsov on the basis of the German Jumo 022 (TV-022) engine and was designed for the installation to a number of aircraft, in particular to the aircraft "94". Its coupled version ( 2TV-2F) was established on the first experiment aircraft "95-1". The engines TV-2f and 2TV-2F passed the large volume of ground and flying tests on the Tu-4LL flying laboratory. Since the beginning of the works on the TV-12 (NK-12) engine work on TV-2 was transmitted to OKB-19 P.A.Solovev, where the engine was modernized and given the new designation TV-2m. By the special feature of flight tests TV -2m on Tu-4LL was the fact that it was mounted to the flying laboratory together with the section of forward fuselage section, which held the compartment of the aircraft "of 91" together with the extension shaft.

The construction of the cabin for the protection of crew from the splinters of anti-aircraft shells included armored covering of plates with a thickness of from 8 to 16 mm. The overall mass of the armor was 568 kg. In the fuselage construction widely used casting from magnesium alloys. For installation and dismantling the engine from above the fuselage was a large hatchway. In the forward section there were three special triplex glass for the pilot, with two special triplex glass below, to the right and to the left. The aircraft was equipped with the ejection seats of crew, which ensured the vertical velocity of abandoning aircraft 20-22 m/s. The seats had shielding shutters, which protected face of pilot and navigator from the air flow.

The experimental aircraft "91" was built at the plant #156. In April 1954 the first prototype aircraft was finished. In the autumn, "91" was transported to Zhukovsky LIiDB and assembled. On November 2, 1954. the test pilot D.V. Zyuzin and the instructor navigator K.I.Malkhasyan accomplished the first official flight of aircraft "91". From October 14 to 17, 1954, ground-based test range [polygon] rocket armament firings were carried out. The original system of rocket armament, jet torpedoes, rocket weapons, containers were initially checked on the aircraft Tu-14. Other systems and assemblies of aircraft were checked and were perfected analogously. After the end of these tests they transmitted aircraft for the joint flight tests for combat employment, which were passed on the naval air station Theodosius until June 29, 1955. The first stage of factory flight tests continued until January 21, 1955.

In the course of this stage were executed 25 flights by the total duration of 14 hours. During the tests was achieved a comparatively low fuel consumption, which made aircraft "91" cheap to operate. For example, in flight to the distance 2100 km with 1000 kgf of the bombs "91" consumed 2700 kgf of fuel (for comparison: in flight to the same distance Il-28 required 6400 kgf).

During the plant and joint testing, from the light hand of ground-based personnel, the aircraft "91" obtained its second, unofficial designation "Bychok" - "bull calf" (also a type of fish). Distributed throughout the Caspian, there are 27 kinds of "bychok", found only in Lake Baikal. A bottom dweller found in rivers and near the shore of lakes, preferring rocky habitats with many places to hide. It preys on small fish, such as darters and the eggs of lake trout, and many other fish. Adult Neogobius melanostomus aggressively defend spawning sites and will occupy prime spawning areas, preventing native species from utilizing these sites. This fish may out-compete native fish for food resources, due to its ability to feed in darkness. The aircraft is also known as "Chiz-Pin-Bog-15Sh" for "Chizhevski, Pinegin, Bogdanov, and Shumov" designers

According to the results of joint testing the aircraft was recommended for series building. Meanwhile in the depths of OKB were prepared the modifications of aircraft "91", intended for the antisubmarine defense, training version and aircraft of radio-electronic opposition. All these works had to enlarge the range of the application "91", it was essential to increase the series production of machines and to thus reduce the prime cost and to also grant to fleet aviation a universal machine.

There were more pure political troubles. There was a competing Ilyushin Il-28 project, and Ilyushin's team was considered to be more skilled in this class of aircraft. Another trouble was that Tu-91 was demonstrated to N.S.Khrushchev with the rocket armament option, despite it was known that Nikita Sergeevich always was skeptical about efficiency of air-surface rockets. In the summer of 1955 the "91" was presented to the leadership of the country at one of the showings of new aviation equipment. The head of state N.S.Khrushchev, after looking under the wing of "91", interested herself in aircraft. An officer said the aircraft could substitutes for a heavy cruiser, instead of saying: "The volley of bombs is equivalent to the onboard volley of the heavy cruiser". Khrushchev reacted to this instantly, and said that if this is so, why do we need heavy warships? All accompanying persons from VVS, Navy and MAP laughed at Khrushchev's observations and quickly came to the conclusion that the aircraft would not enter series production. This episode became prelude to closing of works on the aircraft "91".

The experimental model of aircraft "91" was demonstrated on June 25, 1956 at the Moscow airfield Nubbin to an American aviation delegation, which visited the USSR on an official visit. The head of the delegation was General Nathan Twining. Besides the aircraft "91" it showed the not yet flown "Tu-98" and the Il-54. All three aircraft were experimental, and fate of two of them was already decided that they would not go into series production (Il-54 and "91"). After the trip of the delegation Twining to the USSR, approximate configurations of the aircraft "91" appeared in the western aviation press. The first photograph of the "91" appeared in the western press at the beginning of the 1960. In the photo the aircraft was foreshortened 3/4 from the starboard. Prior to the beginning of the 1990 this was the only published photograph of machine. On the basis it for the almost 30 years were done the very approximate drawings of aircraft, which briefly gave some idea about the "bull calf".

The experience of the local wars of the 1960s forced servicemen to return to the concept of the well protected and heavily armed, comparatively low-speed aircraft, but this was made already in the 1970s, when the attack aircraft Su-25 and A -10 appeared, in some degree the ideas developed in the "bull calf".

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Page last modified: 03-04-2018 18:08:22 ZULU