Questions re Polikarpov-fighters.

[Franek Grabowski]

Originally Posted by Arsenal VG-33

M-88, was different since soviet engeeners ware ambitious and developped it on a different way. Even too much ambitious... Blum governement idea was to exchange french technology against soviet production in 1936. Not a bad idea, but unfortunatly with no continuation.

Never ending romance with communism it seems. I would be very cautious with terms like unfortunately here.

In fact I-18 was tremendously small, see its dimensions. Even with an equivalent or slightly worse Cx value it would be faster. Moroever, it was light: there is no interest in the “modern” or “obsolete” definition, but only on the strenth vs weight ratio. The highly stesses stainless steel 30Kh GSA used on the I-18 airframe (120-140 kg/mm²) was very effective on that way. “Modernity” is a kind of industrial problem, and technically not always the best. In 1939, light alloys were giving 40 kg/mm² resistance, at best. And they were riveted, not glued or welded, with certain loss of resistance on stress lines.

What resistance it is supposed to be? I am not sure what do you want to prove by those numbers. If that steel is stronger than aluminum, then you forget to add, that the former is a little bit heavier than the latter. The same about wood or wood composite. That is why all modern fighters were built of aluminum, and Soviets turned to the technology as soon as it was possible and feasible for them. Otherwise, velocity is only one of parameters defining fighter aircraft, the range being often much more important.

There is nothing to discuss about, it’s only physicall measurements. As for the Eiffel tower lengh or weight. I don’t understand your question. Furthemore, The plane was equipped with the M 88 R (R for reductor) engine that was calculated for 3.6m propellers. The use of propellers less than 3.2m was generating an important loose of the output.

The question is very simple. While performance measurements indicated overall increase of parameters, series aircraft had them substantially worse. The question is valid, but the one must have in mind different configuration, loss of quality caused by series production, possibly less experience of pilots, etc.

There is nothing specially wrong with the MB-152, it was not worse than the american curtiss H-75 (P-36). Of course, it had some developpement problems as for all planes in the world but finally it could withstand without substantial modification the powerfull 1500-1700 hp Gnome le Rhone engine (MB 157).
Polikarpov, was obliged to design a new plane for the use of M 82 and M 71 engines: the I-185.
I-180 itself, had no no more developpement opportunities, except for the Shvetsov M-89 engine.

I understand MB-152C-1 was underpowered, and I think it was not liked by pilots, contrary to H-75. I cannot say for MB-157C-1 though. The point is valid, however, with the lack of development potential. It looks like I-180/I-185 were overstressed, and cancellation was the right decision.