Новые известия(en)
Nails are hammered with a Stradivarius violin: where did the problems with the TV7-117 aircraft engine come from
16 August, 15:31
Nails are hammered with a Stradivarius violin: where did the problems with the TV7-117 aircraft engine come from
Photo: Фото автора.
Recently, absolutely absurd requirements have been imposed on the TV7-117 helicopter engine. You can not demand the impossible from the motor.

Andrey Zlobin, candidate of technical sciences

Recently, we often hear about alleged problems with the TV7-117 aircraft engine. I want to put everything on its head and give my comments as an engine scientist. This will allow to cool the hotheads who make claims to the most modern domestic helicopter engine. My acquaintance with the motor and its developers took place in the mid-1980s after a business trip to Leningrad, where I was sent from CIAM (Central Institute of Aviation Motors). I remember the checkpoint of LNPO named after Klimov, the brilliant designer O.V. Karasev, with whom he talked every day, his colleagues, the premises of the design bureau, drawings on drawing boards and fruitful workshops.

CIAM helped Klimov specialists in the creation of the TV7-117 engine. The cooperation was so extensive that the institute independently developed one of the variants of the motor. Earlier I already wrote that I took part in this work. Under the guidance of experienced mentors, he worked at the drawing board on the design of the engine, performed various engineering calculations. Even then it was clear that the motor was designed for record-breaking parameters and therefore required special attention, including a lot of new technical solutions. The requirements for weight, dimensions, fuel efficiency, resource imposed severe restrictions on the design. Suffice it to say that according to the drawings, I manually calculated the weight of each engine part, each of its components and compiled a detailed weight summary. The work and my report were praised by the head of CIAM D.A. Ogorodnikov. The engine was intended for a helicopter, and this made the task even more difficult, since specific operating conditions were provided for. When taking off and landing, a helicopter, as a rule, raises clouds of dust, especially at unprepared field airfields. Therefore, for all helicopter engines, the high dust content of the air is a critical factor.

For TV7-117, the problem of dust was especially acute. Operating temperatures were planned to be very high, and the turbine blades turned out to be small. It was necessary to ensure reliable air cooling of the turbine so that dust would not interfere with the operation of the cooling system. Central Institute of Aviation Motors analyzed various cooling schemes, including exotic ones, and proposed a new helicopter engine scheme, which significantly increases the efficiency of dust protection. All this great work was carried out under the guidance of the Head of the Turbine Department, Doctor of Technical Sciences, Professor K.M. Popov, who later became the supervisor of my PhD thesis. Actually, the cooling system of the TV7-117 engine became the starting point from which my own studies of heat transfer on the blades of high-temperature and highly loaded aircraft turbines began. The results of these studies were subsequently implemented on the engines of NPO Saturn.

I have had to perform thermal calculations for the TV7-117 engine many times, and in this sense I can characterize the engine as “strict”. This means that many nuances must be observed in its design and production, especially the hot end. That is, the motor requires conservatism in everything related to thermal processes. The strictest technological discipline is a guarantee that the TV7-117 will never let you down. I don’t know how it is now, but the classic version of the engine was well developed in terms of reliability. The complex modes of operation of the helicopter propulsion system, including emergency takeoff and landing, were carefully thought out and calculated. The helicopter gas turbine engine is characterized by special specifics and is very different from the aircraft. In the late 1980s, I watched helicopters "in action" in the field and have a good idea of all the "charms" of real operation.

I was very lucky. In 1988, he took part in an expedition to Podkamennaya Tunguska under the leadership of Academician N.V. Vasiliev. During the expedition, I had the opportunity to fly helicopters, observe the operation of these wonderful machines and engines, and communicate with the pilots. It was especially useful to see the work of helicopters in difficult field conditions, when, hovering over the Tunguska taiga, the pilots meticulously planted a heavy machine on swampy hummocks. At such moments, I made a lot of practical observations concerning the real modes of helicopter motors.

Returning to the TV7-117 engine, I want to note once again that it requires an extremely responsible attitude towards itself. I specifically mentioned a lot of problems that are associated with helicopter engines and which were successfully solved by domestic engine engineers for TV7-117. Many scientists and designers worked on a unique helicopter motor, carefully “tuning” it like a Stradivarius violin. The classic version of the TV7-117 is a technological masterpiece worthy of the highest praise. Unfortunately, what I read in the media today is hair-raising. Recently, completely absurd demands have been made on the engine, at the same time accusing it of all sins. You can not demand the impossible from the motor. What is happening compared to what? For me, as a specialist in aircraft engines, it is obvious that they are trying to hammer nails with the Stradivarius violin.

In the photo: complex modes of helicopter engines: balancing on the verge - a jewelry landing of an expeditionary helicopter on the bumps of a taiga swamp Photo by A.E. Zlobin, Podkamennaya Tunguska, 1988

Andrey Zlobin - Ph.D., in the 90s, head of the engine sector of the Central Institute of Aviation Motors CIAM