Project Su-27KM. Reverse sweep for an aircraft carrier

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Project Su-27KM. Reverse sweep for an aircraft carrier: 

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Scheme of the S-22 fighter, mid-80s. Figure Paralay.com

At one time, the Su-47 Berkut experimental aircraft was widely known. It was distinguished from other equipment by its unusual architecture with a reverse sweep wing (CBS). Sukhoi Design Bureau began to study the topic of CBS in the early eighties and even developed several projects using such a wing. The immediate predecessor of the experimental Su-47 in this context was the Su-27KM project, which offered a carrier-based fighter of an unusual aerodynamic design.

First developments

At the turn of the seventies and eighties, a program was launched in our country to create a promising fighter for updating the Air Force fleet in the nineties. Work on this topic was transferred to the Mikoyan Design Bureau, and the bureau named after BY. Dry instructed to make other aircraft.

In early 1983, M.P. became the general designer of Sukhoi Design Bureau. Simonov. Almost immediately, he suggested starting the initiative development of a promising fighter - without an order from the military. “For disguise” the project was given a working index C-22, which could be confused with the name of one of the production aircraft. The chief designer was appointed V.S. Konokhov.

At that time, Simonov and his colleagues showed great interest in CBS. Studies have shown that such a wing has significant advantages over the "ordinary", although it is more difficult to manufacture. A COS fighter could outperform a normal circuit technique in a number of ways.

The layout of the aircraft S-32. Photo Testpilot.ru

Within the framework of the S-22 project, we conducted the necessary studies and prepared a complete set of working documentation. It was proposed the construction of an aircraft scheme "duck" with front horizontal tail and CBS. The car was equipped with one engine; there was a single cabin. Take-off weight reached 22-24 tons, including several tons of combat load.

Project C.32

At the final design stage, it turned out that the S-22 turned out to be excessively heavy. Correction of these shortcomings required a radical revision of the project. In this regard, work on S-22 was stopped, and the accumulated experience was put at the heart of a new project - C.32.

Now considered the creation of a twin-engine aircraft with increased thrust-to-weight ratio. It was proposed to preserve CBS with all its advantages, as well as to use some ideas in the field of reducing radar visibility. Designers led by M.A. Pogosyan considered several options for the layout and equipment of the aircraft, and then chose the best.

Glider C.32 as a whole was like a previously developed one. Scheme "duck" received an additional rear swivel stabilizer. Above him was a pair of keels. The wing of the reverse sweep remained. The power plant was now made up of two R-79M engines or a pair of developed AL-41F with a controlled thrust vector. In the latter case, access to supersonic speed without afterburner was provided. UVT and CBS were to provide unique maneuverability.

Su-27KM in flight. Figure Popmech.ru

Provided for modern instrumentation of the cockpit, providing unloading of the pilot and the solution of all basic tasks. At the Zvezda NPO, they proposed an original ejection seat of variable geometry, which reduces the effect of overload on the pilot.

“Ship, modernized”

Initially, C.32 was considered as a land-based aircraft. However, by the mid-eighties, the Ministry of Defense began to show increased interest in carrier-based aircraft. OKB them. Sukhoi reacted to this with an appropriate initiative - the development of a deck modification of the S.32 fighter.

In 1988, the preliminary design of the promising Su-27KM fighter (“Ship, modernized”) was prepared. It was based on the project C.32, but was positioned differently. In order not to embarrass the customer with excessive novelty, he was served as a deep modernization of the existing Su-27K (future Su-33).

The main provisions of the Su-27KM project remained the same. A “longitudinal triplane” type glider was proposed with a reverse sweep wing, two engine compartments in the tail, etc. At the same time, measures were taken to strengthen part of the units experiencing certain loads during operation on an aircraft carrier ship. Redesigned instrumentation.

Fighter variant with folding wing. Figure Popmech.ru

Advanced glider offered to build from metal and composites. Metal parts were used in the power pack and partially in the casing. The loaded portion of the wing skin was composite. This made it possible to provide the required structural strength, but made it difficult to place the wing folding mechanism. It had to be outside the projections of composite parts so that they could distribute the loads in the right way.

Developed two methods of reducing the dimensions of the aircraft for a more dense placement in the hangar. In the first case, the hinges for folding were placed in the center section and did not affect the composite part of the wing. The planes had to fold up and down and lie on the fuselage.

The second option did not use wing hinges. Instead, keels laid out to the sides were used. Airplanes of such a scheme, having a minimum height, could be stored on special racks in several tiers.

A power plant with two R-79M engines with UVT was transferred to the "ship" project. The possibility of withdrawing two jet jets through a common plane nozzle with control in a vertical plane was considered.

A flying laboratory based on the Su-27 for testing a flat nozzle. A similar unit could be used on the Su-27KM. Photo Airbase.ru

The Su-27KM project provided for the use of promising avionics and armament control systems. The aircraft was supposed to conduct air battles or attack ground / surface targets. The weapon was planned to be carried on the external sling and in the internal compartment.

The promising aircraft was similar in size to the existing models, and the maximum take-off mass reached 40 tons. With this mass, the aircraft needed a launch catapult, but there were no such units at that time. The alternative was the so-called ballistic take-off from the springboard, which could provide only the wing of the reverse sweep.

During a ballistic take-off, the plane, passing a section of a springboard, has insufficient lift. By inertia, it gains a small height, but then sags by 10-15 m. Reaching the lower point of this decrease, the aircraft develops the necessary speed, and the CBS is gaining lift. After that, the car can confidently stay in the air and perform a flight.

Customer decision

An advance project of the Su-27KM aircraft was prepared in 1988 and immediately received customer support. The research work received the necessary funding, and the construction of a flight prototype was expected in the foreseeable future. However, this did not happen.

Experimental aircraft Su-47 "Golden Eagle". Photo Airwar.ru

In May 1989, the Military Industrial Commission under the USSR Council of Ministers decided to close a number of promising projects in all major areas. Together with other projects, the Su-27KM fell under the reduction. Work on the aircraft in the interests of the Navy ceased. According to some reports, the Su-27KM project was closed in favor of creating the future two-seater Su-27KUB.

The Su-27KM project was closed early enough, and the construction of the prototype did not begin. Moreover, by May 1989 they did not even have time to build and test the necessary flying laboratories. Similar work was carried out later and as part of another project.

From project to experiment

OKB them. Sukhoi was forced to stop creating a carrier-based fighter with a CBS. However, it did not abandon the promising direction as a whole. Work on the reverse sweep wing continued - again in the context of land-based aviation.

Already in 1989, on an initiative basis, they continued work on topic C.32. This project was revised taking into account the experience of developing the Su-27KM. It introduced new solutions, components and technologies. At the same time, I had to abandon some overly bold and expensive solutions. At this stage, flying laboratories with one or another equipment were tested.

Deck fighter Su-33. Due to the failure of the Su-27KM project, he did not receive a replacement. Photo by the Ministry of Defense of the Russian Federation

Soon a new version of the project C.32 appeared, which received its own designation C-37. In 1997, a prototype aircraft of a characteristic type was built under this project, and two years later a car named "Golden Eagle" was first shown to the general public. In the future, this experimental aircraft was involved in various studies, including during the development of the fifth generation fighter.

Predecessor and followers

Thus, the carrier-based fighter with the Su-27KM reverse sweep wing remained on paper, although it had a chance to reach at least flight tests. However, the developments on this project did not disappear, they were implemented and tested in practice. In the future, the pilot project S-37 / Su-47, partially repeating the Su-27KM, contributed to the emergence of a new generation of domestic fighters.

However, the most interesting design decisions of the S-22, S.32, Su-27KM and Su-47 projects did not reach the series and operation in the army. The newest and most perfect Su-57 received a traditional swept wing.

Author: Рябов Кирилл

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