Andrey Zlobin, mathematician, candidate of technical sciences
I must warn you right away that I have not worked in aircraft engine building for a quarter of a century, and therefore my considerations refer to the period of the 80s, when work on the TV7-117 engine was actually just beginning. And yet I consider it necessary to express my point of view. I was then a young engineer, graduated from the Bauman Moscow State Technical University with a degree in Turbo Engineering and a specialization in Aircraft Gas Turbine Engines. According to the distribution, he was sent to the Central Institute of Aviation Motors CIAM and got to work in the turbine department, which was then headed by a remarkable scientist, Doctor of Technical Sciences, Professor K.M. Popov. After a short time, Konstantin Matveyevich included me in the group working on one of the modifications of the TV7-117 engine. This experience became invaluable, since I worked on the design of the aircraft engine under the guidance of the brilliant designers of the design bureau, Professor V.V. Uvarov. Among my mentors behind the drawing board were designers NL Ratushkin, IN Lipatov, BS Pevzner. While working on TV7-117, I had to be on business trips to Leningrad at the Klimov LNPO. Ultimately, I was instructed to make a report on the design of TV7-117 and its weight characteristics at a joint meeting of CIAM and LNPO with the head of the institute, D.A. Ogorodnikov. Our version of the engine turned out to be somewhat heavier and larger, and although it had other advantages, further work on it was discontinued.
Knowing well the design and hot part of the TV7-117 engine, I can say the following. The engine is promising and at the same time difficult in terms of technical solutions. Its axial dimensions are significantly reduced thanks to the counter-current combustion chamber that is located around the turbine assembly. Any aviation turbine operator will say that the turbine "loves" circumferential speeds and a decent diameter. In TV7-117, the turbine assembly is the result of trade-offs caused in particular by the small size of the turbine blades. Imagine that the first stage rotor blade of a TV7-117 turbine is slightly larger than a thumbnail. Rotating at a tremendous speed, such a part must work for thousands of hours at a temperature of the surrounding gases of one and a half thousand degrees (!). In itself, this is already a technological miracle. Nevertheless, this miracle has been realized in the Russian engine and is a huge achievement of the domestic engine building. I understand the significance of this outstanding result, since heat transfer on blades of highly loaded aircraft turbines was the topic of my Ph.D. thesis.
And yet, immediately after the Il-112V disaster, hard-hitting reviews of the engines began to appear. I think there is a lot of emotion in this. Motors TV7-117 are reliable in their classic design. At the same time, on the crashed Il-112V there were forced modifications of the engines, which are not the same thing at all. As I wrote above, the engine is made at the most advanced level of technical solutions and operating parameters, and therefore requires healthy conservatism in terms of any "upgrades". Forcing TV7-117 looks unusual for me, if not “risky”. The engine turbine is already working in very difficult conditions ... The production of such equipment requires the highest technological discipline. It should not be forgotten that the small dimensions of the turbine parts and the cooling system require strict adherence to operating conditions in terms of dust protection, especially for military aircraft. The most dangerous thing that can happen is the destruction of the turbine, for example, due to its overheating. At the same time, debris flying at the speed of a bullet destroys everything in its path, including controls. If the fuel lines or the fuel tank are damaged by the debris of the turbine, a severe fire is almost inevitable ...
A quarter of a century is a long time and, perhaps, my ideas about the current TV7-117 engines are somewhat outdated. But, reading the Russian press, I am horrified by the situation with personnel in aviation and the aviation industry. The aviation sphere is literally flooded with people with chicken brains, who, being in leadership positions, have no aviation technical education at all. Internally, I am convinced that the causes of the Il-112V crash should be sought not in engines, not in the engineering field, and even less so among the flight personnel. There are too many amateurs in the leadership of Russian aviation and the aviation industry today, random people who are blatantly uneducated in terms of aviation. At the same time, the incompetent interventions of such would-be managers in the issues of engine and aircraft construction can have the most tragic consequences. A cold sweat breaks through me at the thought that these same "scholars" may soon try to convert our aviation to hydrogen fuel. God forbid, of course. No, "the bootmaker should make the boots, and the cake-maker should bake the cakes." The Il-112V crash is yet another cruel reminder that everyone should mind their own business. And until the profane and ignorant who have warmed up near the planes are not driven from the aviation with a broom, the tragedies in the Russian sky will not stop.
Andrey Zlobin, candidate of technical sciences, mathematician, in the 90s, head of the CIAM motor sector.