Questions re Polikarpov-fighters.
 

Technical issues relating to soviet aircrafts are not the most popular topic here, but in the faint hope that some "connoisseurs" are lurking here...

The wikipedia entry for the Polikarpov I-180, which is well sourced, names a number of projected developments of the I-16, that I have never seen mentioned before. As I understand it, these were attempts to re-engine the basic design with 14 cylinder, two-row radial engines. derived from the Gnome Rhone Mistral-Major (14K I presume). The are called I-161, I-162, I-163, I-164, and I-165.
These seem to be precursors to the second variation of the I-180, (mixed construction), represented by the second prototype. (I-180-2).

Does anyone have any info on these planes? or know of websites with more information about them?

A related topic. The wikipedia authors relate M. Maslovs conclusions that the I-180 was cancelled for "irrational" reasons. That, over-awed by the Bf 109, the soviet high command cancelled the radial engined I-180 in favour of in-line engined aircrafts. (Lagg-3, Yak-1).

It is a a reasonable conclusion that the Soviet airforce would have been better off with a fully developed design (I-180), rather than immature designs that were not ready, (MiG, Lagg & Yak), although the expected performance was slightly lower.

One noticeable difference is that the M-88 engines seem to have had better altitude capability than the M-105. (Full throttle height of 7000m v. 5000m?) (The tactical significance is beyond my knowledge).

The irony is that it seems that the factory (No 21 in Gorky) ended up producing +- 1000 I-16, type 24 & 29 fighters in 1940/1941. Why?

Could engine availability be the determining factor? It seems that in mid-1940, there where awful lot of applicants for the utilisation of the M-88 engines, (Ilyushin´s DB-3M bomber, Sukhoi´s BB-2 attack bomber, Tairov´s twin engined fighter, as well as Yatsenko´s I-28 project.) Was production-capacity awailable for the required engines. (As contrasted to great supply of Cyclone-derivatives from Perm, lacking applications.)

Anyone care to comment?

Birgir Thorisson

Re: Questions re Polikarpov-fighters.
 

Wasn't that in fact the Su-2?

Re: Questions re Polikarpov-fighters.
 

Hello Birgir,

There is a lot of questions, inside your post:

Not exactly
http://i16fighter.narod.ru/mods/exp1.htm

The first I-161 (1935) was an experimental tip 4 plane with the M-22 engine intended to carry four ShKaS machines guns and four 20 kg bombs. Finaly the decision was made to use 20 mm canons instead.

The second I-161 (1937) was a lighter version intended to have a M 88 engine, but this work was nerver achieved

The number I-162 was never used

The first I-163 (1937) was a lightened version with a M 25 E engine and flaps instead of full lengh ailerons that could be lowered simultaneously on the serial I-16 tip 5 on that time.

The second I-163 had an oleo-pneumatic undercarriage retraction system instead of the standart hand-krank one.

The I-164 or I-16s was a long range escort fighter with extra tanks and a M-25V

None of the two I-165 escort fighter with the M-62 engine an all metalic wing and modified fuselage shape were never flown.

The I-166 was an extra light version (1383 kg at Take Off) with a M-25V engine and a modified NACA coml with adjustable rear slots. Trials were made in 1939

All theese versions were to remain purely experimental

Quote:

These seem to be precursors to the second variation of the I-180, (mixed construction), represented by the second prototype. (I-180-2).

Does anyone have any info on these planes? or know of websites with more information about them?[/quote]

In russian only: http://www.airwar.ru/enc/fww2/i180.html
Try with google translater


In fact the MiG fighter (I-200) was a Polikarpov design too. It was designated “Samolet Kh” by Polikarpov before he was banished from its own design bureau OKO by Mikoyan and Gurevitch, when Polikarpov was outside during his travel with the soviet delegation in Germany. A great surprise when he came back...

In the eastern front, this is a marqued disavantage, virtually all fight took place under 4000m.

Unfortunately those engines (Gnome Rhone and derivatives) we suffering numerous problems and were poorly operational, even in France but they were all pratically resolved in late 1939 versions GN 14N. In the same time, russian leading engeeners of the zavod 29 working on the licenced M-87 and 88 were prosecuted and arrested due to the unsatisfactory work of the french engine. This decision on its turn dit not accelerate the devellopement of the soviet version.
Moreover, when Polikarpov was banished from the powerful state factory n°1 to the experimental factory n°51 (a simple empty hangar in the vicinty of the Khodinka airport) with a very reduced team wich, he had lost his experimental production facilities. Pre-series machines were build at very slow rate in factory 21 at Gorki, when despite official requests, the directors were trying as much as they could to help to the Pashinine I-21 fighter project, due to a local cheef ingeneer.



Sources :
http://i16fighter.narod.ru/index.htm

Polikarpov ‘s I-16 Fighter yefim Gordon and Keith Dexter

Polikarpov I 16, Maslov Armada Moscow, and its french version by José Fernandez Kytka editions

Last Polikarpov Fighters I 180 and I-185 Youri Gouglya Arkhiv-Press Kiev 1998


My opinion: Considering that I-18 reached 575 km/h without canopy and a wrecked unsatisfactory fuselage:
Yes, the virtual speed of 600 km/h was virtualy attained and considering the plane astonishing agility it was probably the best fighter in the world in 1940! But its developpement was too slow and it had no other improvement opportunities.
Polikarpov itself was working on the I-185 project since mid 1939.

Best regards

Re: Questions re Polikarpov-fighters.
 

Thank you "Arsenal VG 33" for your detailed response. The Russian websites look very informative, but unfortunately for me, I have not mastered the use of translation programs.

About sources in other languages. How good is the french Polikarpov I-16 book by LELA press? (Cony, Ledet, Cerda, Louie & Kulikov). I guess sources have become rapidly outdated recently, so you should always look for the latest.

Now, specific topics that you might be able to shed further light on. Re. the M-88 engine. Had the problems been solved in the USSR, at say, decision-time of july 31 1940, (or november for that part.) That is to say, did engine supply questions affect (or determine, if you want to word it more strongly) the aircraft production plans in late 1940/early 1941.
Do you know if the M-88 was a copy of the Gnome-Rhone 14N or a seperate line of development of the 14K. Bearing in mind, the strength of the french communist party, and the fertile ground for soviet espionage in France, either direct official technology transfer, or "industrial espionage" could easily have passed information from France to Russia. (And, yes, let no-one hijack this thread to discuss interwar french politics :) ).

And on a similar theme, and prompted by your nom-de-plume, Do you know if there is any connection between the french interest in "non-strategic materials", (wood), which produced among others the Arsenal VG series in France, and the soviet efforts that led to the Lagg series? Was there anything common in either material, or process of production between the wooden aircraft projects?

A third point of interest. If you compare two designs with a common(?) engine, the Polikarpov I-180, and the Bloch MB 152, the I-180 is much superior in every respect (except, arguably, firepower). Yet the Bloch is a "modern" all-metal monocoque design, the I-180 an obsolete mixed construction. How could that be? How credible are the I-180 performance figures? In Gordon and Khazanov´s book, Soviet Combat Aircraft, the tables at the end give the preproduction 180s superior performance to the third prototype, (albeit with no range information). Yet it seems the pre-production planes were closer to the second prototype than the third.

(I must confess that I have never been able to figure out just what was so wrong with the MB 152).



(And Denes Bernad, yes BB-1 = Su-2, just my flawed memory).

Birgir Thorisson

Re: Questions re Polikarpov-fighters.
 

in one case you might be confusing the I-180 with the I-185.
the I-185 was authorized for series production and a few were used by the 728 IAP.
the reason for their cancellation was made by Josef Stalin because he felt that Polikarpov had 'fallen out of favor'- a decision mostly based on the political mechanizations of A.S. Yakovlev. (I'm sorry to say)
I'm actually not sure of the reason for the I-180 cancellation , most likely that the development wasn't going anywhere.

in December 1940 the designation system in the USSR changed to what we recognize in more recent times.
BB-1 stood for Blizny Bombardarovshik or short-range bomber.
it was changed to Su-2 in favor of it's principle designer Pavel Sukhoi.

Re: Questions re Polikarpov-fighters.
 

No, I am not confusing the I-180 prototypes with the related I-185. Indeed, I would be interested in knowing just how "new" the I-185 was. As far as I can discern, the I-180 was originally conceived as an all-metal aircraft, but never built as such. Maybe, the I-185, (started in 1939) was the all-metal I-180 with the most powerful engine, and with other modifications that came along in those years. They certainly share a very similar general configuration.

Over the last few hours I have been trying to use Google translation on the links provided by Arsenal VG 33. Unfortunately, the program only translates (rather blindly as you undoubtedly know), about half of each page.

Nevertheless, I think that I have gleaned the information, that the M-88 engine failed its tests, in summer 1940, leading to a hiatus, until it was re-certified at the end of the year. There seems to be a record of a) something called "narkomata" deciding that radial engines had no future, and b) that Yakovlev abused his position to further the fortunes of his (inferior) design, the I-26. As result, the I-180 was cancelled. But the case is made, that because of it´s family relationship with the I-16, hundreds could have been made in early 1941, and that the I-180, unlike the Lagg, Yak, and MiGs, would have been bon-de-guerre, as the french would say.

Birgir Thorisson.

Re: Questions re Polikarpov-fighters.
 

http://www.online-translator.com/Default.aspx/Site

I prefer this one as it works much better and it it goes to the bottom of this particular web-page.

Re: Questions re Polikarpov-fighters.
 

"It is a a reasonable conclusion that the Soviet airforce would have been better off with a fully developed design (I-180), rather than immature designs that were not ready, (MiG, Lagg & Yak), although the expected performance was slightly lower."

It would be a reasonable conclusion if the I-180 was indeed a fully-developed design: I'm not convinced that is a fair description. As an aero engineer, the Polikarpov designs (and the MiG 3 is little better) all look to be lacking in longitudinal and directional unstablity, something confirmed by pilots' and engineers' comments on the difficulty they presented to inexperienced pilots. Arguably dead novices are a fair trade-off against agility.

Whether the airframe could have been in production, in the numbers and timeframe you suggest, I leave to others to judge. I'm sceptical. However, if there are no engines it doesn't matter how good the airframe.

On the other matter, as far as I know the VG.33 used conventional wood/plywood construction, and not the Russian resin-impregnated birch. Interior structures can be expected to be similar, although the types of wood used (and hence the details) may be different, depending upon the sources available to each nation. I believe the balsa/spruce sandwich construction of the Mosquito was completely different.

Re: Questions re Polikarpov-fighters.
 

This is what the russian website has to say about the status of the I-180 in May 1940, as translated by Google.

May 20, Polikarpov sent a memorandum Shahurinu, which reported that in the immediate deployment of serial production I-180 plant in 1940, may issue 100 vehicles, including, in September - 10 October - 20 November - 30, December - 40.
In January 1941, the rate of release could amount to 100-120 fighters in a month. Nikolay suggested many changes I-16 remain in production only type 29 and presented a list of activities aimed at ensuring the release of such a program I-180.
At the same time (May 18) completed the second phase of the factory test I-180-3. Unlike the first test machines, at the initiative of Polikarpova on the plane intensified weapons: two 12.7 mm machine gun BS and two 7.62 mm ShKAS were collected into a single battery for the first time in the world mounted on lafete, which simplifies assembly and maintenance. For adjustments "thermal engine hood provided" yubkoy. " Construction I-180-3 was carried out without concessions batch plant, using pressed profiles, stamping, casting.
Already in the first phase of flight tests showed good results: speed - 575 km / h time climb 5000 meters-5.6 min. "According to maneuver the plane was very close to I-16, but more stable and better at superelevation, landing - wrote in a report Ulyahin. - At speeds of less than 350 km / h to 160 km / h, the aircraft has no tendency to stall in tailspin ... With adjusted trimmerami thrown administration remains set to flight. Longitudinal sustainable while centering 24% of SAH good lateral stability and sustainability of the road-good ".
There have been and disadvantages: the lack of lamp cabin, poor adjustment mechanism for cleaning tail wheel, poor design of the screw, poor quality of surface finish. It was expected that after removing the maximum speed reached 600 km / h. Soon the aircraft found the lamp, ordered a new screw, increased V-wing cross. In such a fighter handed over to gosispytaniya in NII Air Force, which took place in a generally successful.

The translation is not very clear, but it seems to indicate that unresolved issues regarding debugging the prototype were rather minor. So compared with the other russian fighters, it was a mature design. (Lamp in cabin, cleaning tailwheel? real problems :) or mistranslations?)
Also the production programme is not unreasonable, in view of the fact that the factory changed over to producing Laggs, using totally different technology, and still produced several hundred machines in the first half of 1941. The proplem of engine supply could have been tackled the same way as the Germans did with the 109E, when the DB601 was delayed, that is, airframes were produced, and stockpiled until the engines became available. This allowed the Luftwaffe to change over to 109E in a short period in 1939. It seems that the M-88 was only in hiatus for 4-5 months in 1940.

Birgir Thorisson

Re: Questions re Polikarpov-fighters.
 

In aircombat altitude is always an advantage! Combat altitude on the eastern front was so low because Soviets had no aircraft able to fly higher.
I would look for a rational reason in regard of canceling I-180. Possibly they have realised they would not have engines in quantities, or the aircraft was too expensive/time consuming. I initially thought that several Soviet decisions were irrational, but this turned untrue, when my knowledge deepened.

Re: Questions re Polikarpov-fighters.
 

Not just Soviet, I'd like to add. The more study that is made of the wartime decisions, and all the factors acting on the decision makers, the more understandable and reasonable their decisons become. Not always right, no, but very rarely (if ever) irrational. Certainly the "bureaucrats and politicians" come out much better than enthusiasts for given types rush to claim.

Which isn't meant to claim that the I-180 decision was necessarily right.

One point that could be made, following on from comments earlier. It was suggested that the Russians would have been better off with an interim type, of known limitations, than waiting for something that promised to be better. When this is done, the interim type tends to stay in production for too long and the better type may never appear. It is all too often assumed that more of the same is better than the loss of production from the changeover to the superior type. The decision point for such a changeover must always have been one of the most difficult in military procurement. I doubt whether many cases could ever be proved either way, but they do provide lots of discussion points for we who follow on!

Re: Questions re Polikarpov-fighters.
 

That is my "hunch" too, with the exception that in cloudy skies, it can become irrelevant, (as happened a certain day over Dunkirk in 1940, when the topcover (Spitfires) above the clouds save nothing, but a fierce battle raged below. (Hurricanes and Defiants).
Somehow, (never having been there), my "hunch" too is that the weather on the Eastern Front was clearer than in the West. (Continental climate, versus Oceanic). May just be my prejudice.
Soviet aircraft were noticably short-legged. That, as well as low altitude rated engines, may explain there disregard of altitude advantage. Too much fuel would be used up in climbing to altitude.

The "rational" explanation for the soviet aircraft production program, must be based on construction factors, primarily engine supply. Now, M-88 were available for DB-3F (Il-4), and BB-1/Su-2. Maybe there was a situation akin to the DB600 situation in Germany, where the engine was just not good enough for fighters. Or, that so much productive capacity had been invested in in-line engines, (M-105 and AM 37/38) that uses had to be found for them. But then, what was the M-82 intended for? The soviets found themselves trying to attach it to all fighter projects, because it lacked application, (but seemingly had plenty of production capacity). I haven´t noticed cancelled programs, that would explain this anomaly of supply and demand.

Birgir Thorisson.

PS, on the translation. Could the "Lamp" be the glass, enclosing the cockpit? Cleaning the tailwheel be retracting the tailwheel?

Re: Questions re Polikarpov-fighters.
 

Graham Boak.

I think there is ample evidence that Stalin erred during WW2 by always preferring quantity to quality. The best case in point being the decision not to put the I-185 into production. If the I-180 had been produced, it would have been a natural progression to move towards the 185, in the winter of 1942/43.

I also tend towards the opinion, shared at it seems by the person using the name Arsenal VG 33, that indeed, the I-185 would have been equal, or better than Yak-1 and LaGG-3, where production aircraft were of far inferior performance to the prototypes. In fact, it took until late 1943, for the last LaGGs to match the prototype performance. Being "older" in production terms, would mean lesser retrogration from prototypes to production. Thus, soviet pilots would have had a better mount, giving better chances of survival, with the resulting cumulative effects on the airforce efficiency. Then there is the unresolved issue of the value of greater altitude capability.

Birgir Thorisson

Re: Questions re Polikarpov-fighters.
 

I've seen 'Lamp' and 'Lantern' used to describe the canopy.
(glass around the cockpit)
as for 'cleaning the tail-wheel' , making it retractable would be my guess as well.

Re: Questions re Polikarpov-fighters.
 

What would the losses of fighter production have been in this scenario, with two cycles of production changeover as opposed to one? What would have the cost been for the additional (re)training of aircrew and groundcrew, and the establishment of different logistical chains, with additional stores capacity required? How did the I-180 and I-185 compare in production costs (time, money, output) with the Yak/LaGG family? Did they use more of materials (e.g. aluminium) that were in desperately short supply? If so, how would this affect other priorities with in the Russian system - other military production and/or mobility over the railway system? More significantly, perhaps, what would have been the losses in bomber production if the limited engine supply was diverted from Ilyushins and Sukhois to Polikarpov? What would all these factors have done to operational effectiveness?

The suggestion that it was a better fighter is not sufficient in itself, even if true.

I have no doubt that better decisions could have been made at the top - show me a country claiming a perfect procurement policy and I shall laugh. However, proving any particular policy wrong takes a lot of evidence, and proving the alternative superior has to depend much on supposition and belief rather than facts. There is, after all, only one history that can (theoretically) be fully described with all the implications known.

Re: Questions re Polikarpov-fighters.
 

I posted this question because I wanted to know if more recent information than I posessed, (mainly the book by Gordon and Khazanov) would throw further light on the issue.
The merits of the various aircrafts do not seem to be in question. Engines are a different matter. The Polikarpovs would seem to be better choices all-around than the others, both from the standpoint of operational efficiency, and producton.

The Polikarpov series were progressive developments of the same basic design, moving towards more use of higher quality materials, which as you say, was in short supply. The decision NOT to produce the 1-185 caused disruption in the production process in 1940/41.
The decision to replace the I-180, (with metalworking share in the airframe construction of ca 1/3 with the LaGGs with only 8% share, meant that factory 21 had to turn metalworkers into woodworkers, and suffered from drastic shortage of skilled woodworkers. As result, production quality was so poor, that a lot of aircraft delivered were useless. Same in Swerdlovsk. It is reported (admittently by a self-serving source, Yakovlev), that when the snow melted in 1942, the around the factory airfield was littered with LaGG aircrafts, and aircraft parts. (It is so veird, that I cannot really believe it, that Factory 31 was turned over from producing all-metal flying boats (including the Consolidated Catalina) to producing wooden fighters. There simply must be something wrong with THAT story).

One could compare it with Britain converting the factories producing Typhoons to produce Mosquitoes rather than Tempests.

As the war progressed, the Yak and Lavochkin design bureaus worked on refining their aircrafts, using superior material. Still, it was only in 1944/45 that their products matched the I-185, the preproduction batch of which was reportedly tested in combat in 1942.
Opportunity cost? By autumn 1942, the Soviet Union was receiving sufficient numbers of Lend Lease fighters, to do without the production lines devoted to producing Lavochkins, for 3-6 months. One must bear in mind that it really only with the La5FN version, that it became a viable fighter, in the second half of 1943.
When you have fighter that your experts tell you that is by far the best fighter in the world, (I-185 as reported in spring 1942), it is really strange not to put it into production.
I would argue that the increased efficency that would be garnered from allowing young pilots to survive and aquire skills to challenge Luftwaffe would in very real "near-term" prove superior to trying to keep the skies full of planes, that only provided convenient cannon-fodder for Luftwaffe experts.

The problems with engine supply is less clear. The I-180 competed with other designs for the M-88 engines. Production of Su-2 was stopped, and the DB-3F continued to be the main user of them, until replaced by the ubiqutious Shvetsov M-82. The M-71 versus M-82 is a complex issue. They were closely related design, and produced in the same factory. Could even be 14 and 18 cylinder versions of the same designs. I dont know. Bearing in mind that both Yaks and MiGs with M-82 failed, and that the LaG-5 and early La-5 were indifferent fighters, the M-82 didn´t become a war-winning asset right away. The opportunity cost suffered by the Red airforce in doing without them for say 6 months, in order to get an even better engine that would provide a fighter that would reverse the quality gap vis-a-vis the Luftwaffe, doesn´t seem great to me.

Regarding material shortages. The priority projects in 1940-41, were the MiG fighter and the NKVD sponsored Samolet 100, (designed as fighers, but became the successful Petlyakov Pe-2). The MiG was then cancelled in favour of Ilyushin Sturmoviks. I would tend to think that the Soviet airforce would have been better served with 1000 I-180s rather than 500 MiG-3s (the exchange ratio is a pure guess), or 1000 I-185, and a thousand fewer Sthurmoviks.

The assumption of rational behavior doesn´t mean that the decisions were right. Looking at a decision, one always finds that there were reasons for the decisions. (Although it can sometimes be hard to figure out what exactly were the reasons for Stalins decisions. A very interesting case is provided by Rohwer and Monakovs book, Stalin´s Ocean Going Fleet, were the authors attempt to deduce from the decisions themselves, what was the thinking behind them.)

If one reduces oneself to only looking at why the one and only history we have, played itself out as it did, and say, this was done for that reason, or not done for this reason, one really puts on a blinker, that prevents oneself from seeing the elements of free will and choice in history. I happen to think that Stalinist Russia was atrociusly managed, and the the peoples of the Soviet Union paid with millions of lives for the inefficency of the system, (and this leaves out completely the deliberate acts of repression.)
I visited Russia two years ago, and I was shocked by the adulation shown for Stalin, mainly for winning WW2. Spending Victory Day at the site of the mass graves in Leningrad (St.Petersburg) brought home to me that the people of the Soviet Union defeated the Nazis, not Stalin, or Zhukov, or the leadership. The shear tenacity of the workers, largely female, who slaved like logs to outproduce the enemy, and soldiers who endured enormous hardships, and died in proportions unknown in the west, produced the vicory, despite a leadership which wasted their work, and threw away their lives with callousnes only rivaled by Hitler or the Japanese.

There is a lot more to be said, but this forum is probably not the place for it.

I am off for the Christmass holidays, and will not be checking back until next year. Thank you all who cared to comment.

Happy holidays to everone who seas this post, and may you all prosper in coming years.

Birgir Thorisson

Re: Questions re Polikarpov-fighters.
 

Hello Birgir

Sorry for being so late, a lot of job here!
Happy new year anyway!

Quote:

About sources in other languages. How good is the french Polikarpov I-16 book by LELA press? (Cony, Ledet, Cerda, Louie & Kulikov). I guess sources have become rapidly outdated recently, so you should always look for the latest.

Avoid it as much as you can, a very low level of knowledge, too much errors. The same for Polikarpov Fighters in action, squadron signal n° 162.
Polikarpov I-16 Fighter from Gunston and Dexter, is a little better but less than average in all and...quite boring.

In my opinion the best book for the I-16 in english translation would be the J Kytka editions one, because il’s the closest to the original Mikhail Maslov’s book:
http://www.aerostories.org/~aerobiblio/article18.html
but there is a very little information about the I-18/185.

Quote:

Now, specific topics that you might be able to shed further light on. Re. the M-88 engine. Had the problems been solved in the USSR, at say, decision-time of july 31 1940, (or november for that part.) That is to say, did engine supply questions affect (or determine, if you want to word it more strongly) the aircraft production plans in late 1940/early 1941.

AFAIK, the M-88 was "put in production" again on automn 1940, after it had passed with success the second batch of state tests on previous summer. In fact, no production was stopped, only deliveries during the state investigation due to numerous complaints from VVS units.
)
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.

Quote:

And on a similar theme, and prompted by your nom-de-plume, Do you know if there is any connection between the french interest in "non-strategic materials", (wood), which produced among others the Arsenal VG series in France, and the soviet efforts that led to the Lagg series? Was there anything common in either material, or process of production between the wooden aircraft projects?

I only know that zavod 301 in Khimki was preparing (slowly) the Caudron 690 production in Russia (and about the high opinion of Yakovlev for french wood designs) , when it was roughly occupied by Lavotchkin bureau and quckly turned to the LaGG production. But the later was rather a composite plane, than a wood one because of the delta D materials.

Quote:

A third point of interest. If you compare two designs with a common(?) engine, the Polikarpov I-180, and the Bloch MB 152, the I-180 is much superior in every respect (except, arguably, firepower). Yet the Bloch is a "modern" all-metal monocoque design, the I-180 an obsolete mixed construction. How could that be?

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.

Quote:

How credible are the I-180 performance figures? In Gordon and Khazanov´s book, Soviet Combat Aircraft, the tables at the end give the preproduction 180s superior performance to the third prototype, (albeit with no range information). Yet it seems the pre-production planes were closer to the second prototype than the third.

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.

Quote:

(I must confess that I have never been able to figure out just what was so wrong with the MB 152).

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.

Best wishes

Re: Questions re Polikarpov-fighters.
 

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

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 isn´t 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; Joanne´s 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 France´s 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 it´s 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; Don´t 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
Wasn´t 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

Re: Questions re Polikarpov-fighters.
 

[quote]
I would be very cautious in my turn about your knowledge in the catastrophic situation in the french industry in 1936. We were desesperatly trying to resolve problems, by different ways. I personnaly think that the Polikarpov I-17 produced in the USSR with licensed tree-bladed Ratier prop and hispano engine could have been a good temporary solution.


Oh, really? You see that...
Well read my post again...about 1940, thin tubes, chromansils end etc...


Stap'me! Did you find it by yourself once more, without any help?
Thank you for all this "Lapalissades"* (*trivial evidencies from Lapalisse a french Phylosoph from the Rennaissance aera).
But read Shavrov, Kosminkov: sometimes it was the opposite.


Are you still kidding? I-180, was no more overstressed, understressed either hyperstressed than the others soviet fighters of its time. It was just responding to the soviet specification standarts of the year (7,5-8G, i thing). Maybe more, but NOT LESS. Furthermore before building a plane you have to send a complete file of calculations to the state acceptance commission, and theorycally wait for a positive answer.

But you might be very youg, ask to your older poles what was it to be leaving under soviet (heavy) administration. Even Kafka, would have not enough imagination...

Your Faithfully,
Arsenal

Stay high!

Re: Questions re Polikarpov-fighters.
 

Hello!

I am sitting on the fence on the topic of this thread. But about the materials. With the values you give steel with strength 120 kg/mm2 has less than 4% better strength/weight ratio than "light alloys".

But can you make whole airframe out of steel? No! Usually steel is used only to make the load carrying members like fuselage tubular frame which has to be covered to get the aerodynamic form. Many times it was aluminum "roof" and fabric covering below that. Steel fuselage frames most often were statically determined meaning there was no alternative load paths if the frame tubes were damaged. I do not know if this was generally taken in account in design.
BTW the delta wood was similar to steel in the use - it was used only where high strength was needed (spars, stringers). Not for whole airframe.

For light alloys the design is usually totally different. The whole "cover" was load carrying element which was supported by frames and stringers against buckling/collapsing (some reversible buckling of panels is usually allowed for). Conservatively designed stiffened structure usually had redundancy and provided multiple load paths even when damaged ("fail safe"). Curtiss design is a good example.

In the real light structures stability is usually of more concern than material strength. Even in tubular frames. If so, then the much higher density of steel becomes literally a burden. There is no use for the extra strength of steel over light alloys then.

Plus. Was the "30Kh GSA" steel really stainless? Was it weldable, and how easily?

As far as I know steel frames usually were of chromolybdene (spelling) steel like AISI 4130 (good weldability). It rusts easily, the high-strength version (4130N) rusts like hell. I have right now one test series in environmental chamber downstairs, a work project. It was covered with rust spots within hour when in 60 degrees Celsius/95% relative humidity. Aluminum 7075 - both clad and bare - have got only some oxidation spots after couple of weeks. Another thing to ponder in design.

Regards,
Kari

Re: Questions re Polikarpov-fighters.
 

Hello

Quote:

The problem I have with the relative performance of the pre-production series I-180 relative to the third prototype isn´t about the expected fall in performance with mass-produced aircrafts versus hand-crafted prototypes, as Franek Grabowski deduced.

On that point, Franek is right, but pre-production and the very first serial aircrafts are usually better in USSR, than the mass-produced ones.

Quote:

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?

According to Youri Gouglya, the I 180-3 had many defaults noticed during state acceptance trials reports (may 40)

-lack of the plexiglass canopy
-unsatisfactory work of the tail weel retraction system
-unsatisfactory propeller
-rough surfaces in general (high rugosity)

-and from Polikarpov letter, wrecked (twisted) fuselage...

But it was considered, once those small problems resolved the plane would easily reach 600 km/h. In other worlds, virtually this contractual speed was attained and aircraft officialy accepted for production.
Heavier? But at 2429 kg the I-180S had only 4 kg more that the I-180-3.
Look at http://articles.gourt.com/en/Polikarpov%20I-180

So, in order to reassure Franek, the serial aircraft did lost some performance...


I will exchange you with great pleasure some scans from Googlya and Maslov books about i 180 against your4S MB 152 by PM. It’s rather expensive even for me...

Quote:

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.

I wouldn’t say that, the Hawk was much more reliable in terms of MTTF and MTBR (mid time to fault)/ (mid time to repear) and the Bloch a kind of “hangar queen”. But this latter point was progressevely improved...
Both of them were underpowered and slower than the Me 109E but could outfight it in a turning circles dogfight.

The rest for tomorrow...

VG

Re: Questions re Polikarpov-fighters.
 

Steel was often used for spars, in order to increase stiffness.
I presume you know the answer, as you would not ask not knowing it, would you?
Another good temporary solution would have been to establish Gulag archipelago across the Europe and to send there people's enemies. Certainly it could substantially improve the French industry.
Yes, I have read, and I stand by my comment, that steel is still heavier than aluminum. Feel free to think otherwise, if you want.
I do not know what has Shavrov or Kosminkov or even Lapalisse to the question of Birgir.
I am not sure if this was the correct word, but I have no better one. Nonetheless I see you are confusing things. One thing is to withstand specifications, say that 8G, and completely another a safety margin, size, etc. allowing for installation of more powerful engine, heavier armament and equipment, additional fuel, etc. The best case of such development is Spitfire which started as 1000 hp powered bird with 8 mgs, and ended as a 2000 hp beast with 4 cannons and ordnance racks, this without any major structural changes of the basic airframe. If any modification of I-180 required to redesign the aircraft, then it was absolutely justified to cancel it.
What calculations?!
I am old enough. But even they did not manage to turn a carrot into a fruit nor to consider curvature of banana.

Re: Questions re Polikarpov-fighters.
 

Sorry Birgir,

I have missed your post here:

The real translation is lack of the bulkhead, non retracting tailwheel

Now considering the same plane with

satisfactory prop ( + ? km/h)
enlosed canopy (+ 15/20 km/h)
retracted tailwheel ( + 5 km/h)
highly polished with accurate fuselage lines (+ 10 km/h)

I would say YES, the plane would be faster than 600 km/h!




The Lagg was a technological "beast" since it could reach 515 km/h at SL with only 1020 hp. But a kind of industral disaster too, cause resins used to make the Delta D were travelling from the USA to USSR through germany.


AFAIK, problems with M 88 occured when soviets were trying to put in production a new M-88 with 200 hours (300h?) overhall, instead of the old one (100) (150?). I don't remember original values exactly... No production was stopped, only deliveries and flights with the new modernized engine, during state investigation tests in summer 1940. Planes with the old engine versions were still flying...

Best regards

Re: Questions re Polikarpov-fighters.
 

Hello Kari

[quote]
But 120 kg force is an exceptionnal value for mid 30ies! In France we use 80-95 kgf/mm² even in mid 40ies.
38-42 kg is usual for dural, anywere.

The same for delta D. with 27,4 kg/mm². French "hardened woods" were weaker, even with the same density.



The best repartition "load" for cover is obtained in a monocoque structure, wich is even better in that way that the Vickers "Geodetic one". It's why a wood plane could be lighter (Arsenal VG against Dewoitine 520) or equivalent to à dural one, even with the disastrous weight/resistance ratio of wood materials. Cf Mosquito. Even with oregon pine or balsa.

If Dural is a superior material by itself and you have a lot or very strong plane parts only attached by rivets one to each other. Don't forget the whole plane balance (in 1938 of course) count also the weakness lines due to holes for rivets, and the advantages of the glue and welding techneakes.




two links:

http://www.viam.ru/index.php?section=169&language=2

http://www.metaltrade.ru/abc/x/2257.htm


AFAIK 140 kg/mm² is a value fo clean metal, 120 for the welded one.
Stainless is a translation from the dear Green-Swanborough-Dexter Gordon books.
Haw stainless it was, how was it weldable? Better wright or mail to the VIAM. I only know that this metal Chromansil was used in thin welded tubes in I-153/i-16, 18; Yak airframes.

I'm not fluent in AISI standards, i'm using french XC ones. But i'v got a friend of mine working at L'Institut Français de la Soudure, as an inspector. If problems persits, he will tell you what to do.

Best regards

Re: Questions re Polikarpov-fighters.
 

Smooth aerodynamics does not make a perfect fighter alone. Otherwise I am not sure what are you trying to prove.
May I ask again, what resistance are you comparing?
Wooden aircraft will never be lighter than a metal one. IIRC Mosquito was about 1,5 ton heavier than a contemporary metal aircraft, though better aerodynamics was certainly a gain.
It is superior, and that is why we are doing metal aircraft, not wooden ones.
I bet Kari knows the answer. The question is if you know, what are you writing about.

Re: Questions re Polikarpov-fighters.
 

First I didn't follow the complete thread, and second I am not an expert.

Just some random thoughts.

The design philosophy I-180 seemed to have lived on in the I-16x-series you mention, the I-185 and even the MiG-1 (!) and its many derivatives. Even if many of these didn't reach production status, it appears that enough effort was made to do (extensive) research and develop these types.

By the time the I-185 might have been the best Soviet fighters, there were thousands of aicraft of established types rolling off the production lines that had nearly equal performance. Development life of these contemporaries wasn't exactly short and unsuccessful, both Yakovlev and Lavochkin fighters started a (direct) line of high performance piston engine fighters that served until the arrival of the jet.

Polikarpov may just have been unlucky, the loss of Soviet hero Chkalov in the I-180 prototype, his I-16 and I-153 being obsolescent at the start of the second world war, finally the misuse of the MiG-3 (forced to fly under conditions that did not bring out the best it had to offer - high altitude performance).

The radial engine I-180 might just had the bad luck to have been introduced when inline engines were the vogue (and arguably for the right reason). Radials just took a while to catch up again.

Re: Questions re Polikarpov-fighters.
 

No need to ask, just read!

Give us an example

About we i don't know. You are certainly doing nothing. I have restored a wooden JoDel wing.

No comment. Just read my posts and links.

Re: Questions re Polikarpov-fighters.
 

I am just doing that, and I cannot find what resistance do you mean. You do not know too much about resistance, do you?
Do it yourself, compare such aircraft like Beaufighter, Invader, Ju 88, Me 110, etc. and draw your own conclusions. Or calculate if you can.
When was Jodel designed and was it a high performance aircraft?
I am just doing that, and my impression is that your knowledge on the subject is quite limited.

Re: Questions re Polikarpov-fighters.
 

[quote=Franek Grabowski;79608]
And what are you thinking of? That i gave you break limits (Re) for Delta D or Steel and elastic (Rm) one for Dural.

Don't worry for me, be useful just one time, sent us your values.

Can you show me a wooden Beauf, Invader or Ju-88, or a metallic Mosquito?

So what?

What is your problem?

Can you reapeat the question please?

Re: Questions re Polikarpov-fighters.
 

Hello!

This thread is on the borderline to bother with an answer.

About the steel 30ХГСА. I was not familiar with the Soviet/Russian material codes but my own searches and the given links helped.

To be stainless steel the material should contain at minimum 11% chromium, usual amount is around 18%. Steel 30 HGSA data is given here:
http://www.metaltrade.ru/steelinfo/30xgsa.htm
The steel contains only 0,8-1,1% chromium. No way it is a stainless steel. It is a structural steel and is it possible that some of the letters "GSA" mean drawn, seamless tube? Because that it is, the 30 HGSA steel.

My suspicion was awakened because stainless usually is not that strong. Welding makes it weaker and prone to corrosion if it is not post-treated by removing the low-chrome layer either chemically, mechanically or both.


Wood is light and IMO good choice for structures with low loading. Case in point is MiG-3 rear fuselage which was work of art. Veneer layers bonded over mold; light, strong, aerodynamically and estethically beautiful piece. Actually all material choices with MiG-3 make engineering sense if you ask me.

For high load structures like wing spars wood is not the best material. Steel strip spar caps do not help if they cannot be bonded reliably to the wooden structure, screws are not enough to transfer the load. As Soviets found out too? Another problem is joining the wooden parts to the rest of airframe. Many a Il-2 did throw off their wing(s), rear fuselage or tail when they were hit in some hard spot. In one case Il-2 lost it's tail after getting AAA hit on wing gun barrel. The big wooden wing spar box in Jak-7 (Jak-1 too?) ate much of the wing inner volume which could have been used to store fuel. Short endurance was the achilles heel for many Soviet fighter types. Bingo fuel for La-5 - even FN - meant that Brewsters could turn the tables in battle.

One problem with wood and also composites like carbon fiber is that they have no plastic deformation like metals have. Shot through aluminum skin makes hole, but the shock damages wood (typically veneer layers, plywoood) in larger diameter area around the hole. This is even more pronounced with carbon fiber laminates, BTW. Most dangerous are outwardly invisible damages in laminates (delaminations).

BTW About the AISI 4130N test pieces and corrosion. We are testing something else where the corrosion of outer surfaces does not factor in. It was problem (nuisance) known beforehand.

Cheers,
Kari

Re: Questions re Polikarpov-fighters.
 

Indeed, it is hard to discuss with people, who believe stone is a perfect material for aircraft.
Check German 14 342, this should be similar.
Yes, it is corroding, rather hard to weld and prone to breaks (sorry, I am lacking technical vocabulary), so there are some penalties. HGSA stands for chromium, manganese, silicone, with reduced phosphorus and sulphur. The number shows percentage of carbon. It is offered in a wide range of products, including seamless drawn tubes. Obviously it affects resistance, and figures given seem totally bogus for me (unless I cannot convert them to MPa).
Any source for those figures?
http://www.spawalnictwo.com.pl/index...umer_watku=586
Do you see any difference?
Do you have any idea about estimating weight of aircraft? I see you do not.
So nothing, perfectly nothing.
I do not like BS, and you spread BS as hell. Like many other anonymous users, you try to lower the level of discussions to the dangerous bottom. That is all.
You got the answer.