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Re: Questions re Polikarpov-fighters.
Arsenal VG-33
Thank you for your input.
The problem I have with the relative performance of the pre-production series I-180 relative to the third prototype isnīt about the expected fall in performance with mass-produced aircrafts versus hand-crafted prototypes, as Franek Grabowski deduced. The pre-production aircrafts are less developed than the third prototype. They have the same powerplant, (M-88R), but are heavier, and are without the aerodynamic "improvements" of the third prototype. Yet, they are supposed to be faster, and with a higher rate of climb.
Are you saying that the difference is due to the pre-series having larger propellers?
The alternative explanation is that performance measurements are in some way "doctored", as is alleged that Yakovlev did for the Yak-1, and as Bloch did for the MB-152. (I bought a rather expensive book; Joanneīs Le Bloch MB 152, mainly in order to find out the details of that story, but although superbly detailed in almost every respect relating to the MB-150 series, he just mentions it in passing, confirming that the test figures were indeed faked, and then goes on to other subjects.)
I disagree with you about there being nothing wrong with the MB 152. As the late Gaston Botquin argued 30 years ago, the Curtiss H 75 was a far more effective fighter.
In industrial terms, the MB-152 should have been Franceīs Bf.109. It was a big mass-production project. It had all the features of a modern fighter, and it had as powerful an engine as was available at the time. The GR-14, N-49 is comparable to the DB-601 and RR Merlin III. Now there is a tendency to argue that radial engines need to be more powerful than inline engines, for the same speed, but, if so, how do we explain the Mitsubishi A6M2? The Curtiss was slower, even with itīs best engine, (H75-A3), but then, it was a much bigger plane. (I have 1/72 scale models standing side by side). The MB-152 was actually slower than the twin engined reconnaisance-bomber MB-174, which is much more than twice the size in the terms of volume and surface area.
Therefore, there must have been something seriously wrong with the aerodynamics of the MB-152. (And yes, the MB-157 was as much a new design as the I-185).
Compared to British, American, and Japanese designers, French and Russians (and even Germans) went for the biggest engines, in the smallest airframes, with the smallest wings they could get away with.
It is therefore understandable that Polikarpov was incrementally enlarging the wing, as the I-180/I-185 series was evolving. It seems that the I-185 was an incremental development of the family that started with the I-16, using mixed construction, but going for more advanced materials in the wings. The same path was followed with the La-7 and La-9 and Yak-3.
I do not see a logic in Franek Grabowski deduction that the designs was in some way overstressed, and therefore not viable. The FW-190 is also a very compact design, with high wing-loading. The primary "cost" of this configuration is high landing speed, and a long landing/take-off runs.
To recapitulate my line of reasoning.
1) There is a choice between optimal, and the best technology. In 1940 Soviet authorites decided to go helter-skelter for the most advanced protypes (Yak, Lagg, and Mig) and cancelled the seamingly inferior development (I-180) of there now obsolescent standard fighter, (I-16).
As result, the bulk of the trained soviet figher pilots was lost in 1941, in a battle of attrition, flying either old and obsolete aircraft, (I-15 & I-16), or uncombatworthy production examples of unfinished prototypes. (Yak, Lagg, Mig). (This is a hypothesis, I have not been able to find data about a) numbers of pilots, b) standard of training, or c) rates of attrition, in 1941).
I would argue, that more pilots would have been able to survive, and improve their skill, while inflicting more damage on the Luftwaffe, in a mount like the I-180, rather than actually happened historically. On paper, the I-180 is comparable to the Spitfire I. Production versions should have lesser retrogression than the new types, so production versions should be rated as better than the Hurricane II, and comparable to the Tomahawk II. Not quite a match for the Bf.109F, but better than what they had.
2) There is choice between quantity and quality. Historically Stalin issued a dictum, which I have seen expressed so in english; Donīt touch the production line! As result, the soviet aircraft industry was mass-producing huge numbes of Il-2, Yak1/7/9, and La-5 from 1942-44, with little improvents in performance. Real advances coming mainly with the Yak-3 and La-5FN in 1944. (Yes some La-5FN were produced late in 1943). Superior types were available, from the Polikarpov and Mig bureaus. The earliest, and the most promising was the I-185. If the I-180 had been produced, it would not have been question to switch over to the I-185 in the winter of 1942/43. That is why the decision to cancel the I-180 is so important. But even in hindsight, it would have been preferrable to switch, IF the M-71 could have been produced. That is the one technical issue that really is obscure. Zavod-21 was turning out about 400 La5 a month. These aircraft were still suffering from teething troubles, resulting from the shotgun marriage of a big radial engine to an airframe designed for an inline engine. If the change-over had taken 3 months, the loss of output would have been 1200 planes, if 6 months, the loss would have been 2400 aircrafts. These are large numbers, but in the end, what matters is the effective frontline strength, not the numbers of unsatisfactory planes sitting at depots, repair facilities, or training centres. If the Soviets had fielded a few chosen IADs with 2-300 I-185s at Kursk, my estimate is that they would have done a lot better than what the 2400 mostly absent, and inadequate La-5s bought them.
PS
Wasnīt the M-89 of the Gnome-Rhone lineage, (Nazarov/Tumansky), rather than Wright Cyclone/Shvetsov? Maybe related to either GR-14P or GR-14R?
Birgir Thorisson
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