Yakovlev Yak-3 v. Bell P-63 Kingcobra

Tante Ju said:

See also American Muscle cars to a European sports car like Ferrari or Porsche.. the American way always seem to be "go big", like if "big" has a quality on its own.

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BIG does have a quality all its own in this aspect ( cars )...it was luxury. it reflected "the good life" after the war and the prosperous years after. you had room for your wife, kids dog, and aunt harriet and not be crowded. was it extravagant...probably.. but that doesnt make it wrong. its what the people wanted as a symbol of personal success in life...the american dream. some car manufacturers also made small efficent cars...like the chevy corvair. most of the cars made by rambler...especially the nash, were along the lines of european cars...not the sports cars, but family auto, but these were less popular and didnt sell as well. so the correlation between euro and us cars doesnt fit in this picture except that it was built to please and serve a purpose/role.

Tante Ju said:

All Soviet fighters were light weight.... I fail to see that such doctrine of lightweight fronline fighters was somehow forced onto Soviet by invasion. They had the same doctrine and fighters before and after the invasion.

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soviet ac sacrificed survivability for performance. they seemed to have had the same mindset as the japanese who also didnt armor their fighter ac too much either. problem was russia had more men to replace lost pilots with and the japs didnt. russia was able to flood the skies with ac while japan saw theirs dwindle. i cant remember which bio i read of the LW pilot. he remarked that they would shoot down 20 vvs ac and the next day there would be 80 more of them in the air. if you would armor a yak ( or a zero ) to give the pilot the same survivabilty rate as a western ac....they would have not preformed nearly as well and very welll could have been out classed by existing ac. had the eastern war been fought at high alt like the western war...it would have been interesting to see what the VVS would have fielded.

bobbysocks said:

had the eastern war been fought at high alt like the western war...it would have been interesting to see what the VVS would have fielded.

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Probably developments of the MiG-3, with better armament and more power. High altitude was the only thing it was good for.

The Russians had a sever and chronic engine problem. It was probably made worse by the lack of high performance number fuel. The Russians were lagging behind Britain, the US and Germany in the development of high powered aircraft engines. They had plenty of ideas but lacked the ability to turn them into reliable high powered engines. I don't know if was lubrication oil, bearing materials, rare elements for alloys, heat treating technique or combinations of these and more but the Russians were usually a step or two behind when it came to production engines.
This meant certain things had to be sacrificed in order to get adequate to good performance. Russian aircraft were actually fairly well protected and the Russians had adopted some very good performing guns that were very light in relation to their power which helped offset their poor performing engines.
I am sorry but M-105P fitted to the prototype Yak and Lagg fighters in 1940 offered 1100hp for take off at 6500ft and at 1050hp at 13,120ft. Unfortunately this is as close to western engines as the series got until the end of the war. The Merlin had been making 1030hp over 3,000ft higher for over two years and the early Allison could make 1040hp at 14,300ft.
The M-105PF got to 1210hp for take-off and and 1260hp at 2,625ft and 1180hp at 8,860ft. First flight in a YAK-1 in June of 1941. Allison is already in production of teh -39 with 1150hp for take-off and 1150hp at 11,800ft. British have had the Merlin XX in production for a year. By 1943 the Russians have advanced to the M-105PF-2 which offers 1244hp for take-off, 1300hp (1290?) at 2625ft and more importantly 1240hp at 13,210ft. unfortunately it comes at a cost of 30% less time between overhauls. Allison is offering engines with 1200hp for take off and 1150hp at 14,500-15,000ft. not including turbo models. R-R had the 60 series Merlin in production, early Griffon single stage and starting two stage Griffons. There is a M-105PF-3 and M-(or VK) 106 and 107 engines but the first offers scant improvement and latter 2 offer bad reliability and are in and out of production like a revolving door. The 107 finally makes it about the end of the war.

The Klimov aero engines were just one 'line' of what Soviets have had. The 2 speed AM-39 was good for 1500 HP from circa 2 up to almost 6 km (ie. up to 19000 ft), while the M-71F (18 cyl radial) was making 2200 HP at take off.

Yep and the AM-39 (developed from the AM-35) was a 44.66 liter V-12 ( the displacement of the DB 603) that weighed several hundred more pounds than the DB 603, it was never used in a production aircraft.
The M-71F????

From Wiki so take as you will.
"Development began at the beginning of 1939 and it was bench tested that August, but did not pass its State acceptance tests until the autumn of 1942."
Granted the German Imvasion may have messed things up a bit.
"Despite this it was flight-tested in a Polikarpov I-185 prototype fighter in March–April 1942. A boosted version, the M-71F, was built in small numbers. It was flown in the prototypes of the single-engined Su-6 and the twin-engined Su-8 ground-attack aircraft in 1943–44 as well as the La-7 fighter in 1944."

"Evaluations of the M-71 were generally favorable, but no production capacity was available to use for a brand-new engine during the war"

Oookay, but the TU-4 (B-29 copy) used the M-73 radial engine post war.



And you had the M-72 in between. Was the M-71 really ready for use?

Edit> I believe the M-70, M-71 and M-72 all used the same cylinder dimensions?

Shortround6 said:

Yep and the AM-39 (developed from the AM-35) was a 44.66 liter V-12 ( the displacement of the DB 603) that weighed several hundred more pounds than the DB 603, it was never used in a production aircraft.

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If we are to believe Wiki, it's 2380 lbs vs. 2030 lbs for the AM-39 - not such big a difference. That it was never used in production aircraft has nothing to do with engine's qualities - Soviets wanted the low level Mikulin for their Sturmoviks far more.

The M-71F????

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Indeed, the 'forced' version of the M-71 (2200 HP for TO vs 2000). Bolded in the excerpt:

From Wiki so take as you will.
"Development began at the beginning of 1939 and it was bench tested that August, but did not pass its State acceptance tests until the autumn of 1942."
Granted the German Imvasion may have messed things up a bit.
"Despite this it was flight-tested in a Polikarpov I-185 prototype fighter in March–April 1942. A boosted version, the M-71F, was built in small numbers. It was flown in the prototypes of the single-engined Su-6 and the twin-engined Su-8 ground-attack aircraft in 1943–44 as well as the La-7 fighter in 1944."

"Evaluations of the M-71 were generally favorable, but no production capacity was available to use for a brand-new engine during the war"

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So the Soviets have had what it takes, but were out of factories. Again, the engine was just fine.

Was the M-71 really ready for use?

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Far readier than R-3350, BMW 801, or Sabre were when introduced.

Edit> I believe the M-70, M-71 and M-72 all used the same cylinder dimensions?

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Beats me

-added:
this might be some fine reading:
Google Translate

The Russians, at times, were more than willing to order engines into production before they had passed official acceptance tests. Sometimes this speed the process up and sometimes it was the engines equivalent of the Blackburn Botha, Hundreds of engines that nobody wants to see in an aircraft.

The point with the AM-39 is that is lower in power and heavier than a DB 603 and not much different in timing. The earlier AM-35 was a fair achievement at the time and the swirl throttle was certainly interesting and shows the Russians could be inventive and innovative. But 830 kg for a 1350hp engine was just too much. Using a really big basic engine may be simpler than using two stage engines or turbos but it still means a heavy engine installation. The Russians seem to have had a fair amount of trouble with their "follow up" engines, How much of an excuse the "lack of production facilities" is I don't know. I can believe it in 1941/42. It is even believable in 1943, it starts to become suspicious in 1944.

Like the 18 cylinder radial. One design bureau worked for (on and off) for 7-8 years on it. from wiki:

"The progenitor for the ASh-73 was the M-70. It was tested in late 1938 and was a failure because of cracks in the master connecting rod and the geared centrifugal supercharger's impeller. The exhaust valves also burnt through. The M-71 of 1939 was the successor to the M-70 and it too was not a success. It used some components from the M-62 engine, but its development was slowed by the German attack on the Soviet Union in 1941. It passed its State acceptance tests in the autumn of 1942, but was not placed into production as there was not any production capacity available, although it was tested on a number of different prototypes during the war. The M-72 of early 1945 was a boosted version of the M-71 and was superseded by the ASh-73 before production could get underway"

If the engine is "FINE" why design two more versions of it? Why wait until 1947 to get into production?

I love this sentence in Wiki on the VK-106 engine "Although reliable and easily installed in M-105-powered aircraft, VK-106 did not enter production because its cooling problems were not solved."

Reliable yet cooling problems were not solved???? it's either one or the other. BTW at least several hundred VK-106 engines were built. Maybe not "production" by Russian standards but either factory space wasn't that tight or they were desperate for better performing engines.

Try this from Wiki on the VK-107.

" Although the engine could have been ready for production as early as 1942, Soviet factories lacked the capacity to produce a brand new design."

and then several sentences later, ". VK-107A was put into production in 1944 and was used on Yak-9U fighters. The engine was not well liked by either pilots or mechanics -- it had a life expectancy of only 25 hours and war emergency power was almost never used for fear of decreasing this even more."

Now they have had 1 1/2 to 2 years to work on it, the Germans are retreating (being forced back, your choice) and at this point 1650hp for take off and 1450hp at 12,500ft is the best that they can do from a 35liter 765kg engine with one of the shortest life expectancy's since the First World War? The desperate need to produce every engine possible should be easing up.
I wonder what the 1942 version would have been like?

VK-107s were used postwar and may have been used in Korea.

Not to pick on the Russians too much and to show that "ready for production" may not turn out all that well, we all know the Wright R-3350 was just an 18 Cylinder version of the R-2600 and that it took a number years to get the R-3350 to run even somewhat satisfactorily, Some old B-29 crews may argue with that.

FWIW, the Klimov (and many other) engines do need a well researched book, that would draw it's informations from state archives. Wiki articles on techincal stuff are really messy, especially when we real English language version that deals with ex-USSR technicalities.
In the book about the fighters (by Gordon Khazanov), the M-105 follow ups (106, 107, 108 ) are many times claimed as unreliable not really acceptable for the combat use. You can note that I ( a renown expert on everything and anything )did not claimed othervise

As for the AM-39 and M-71 - same thing, we need a well researched book. How much of priority was given to those? Were they regarded as necessary worthwhile in the time their mass production was to be started? Were the Soviets better to have a bird in the hand (2000 HP) or a pigeon on the roof (2200 HP)? The article, link provided at above post, covers some issues about the soviet engines, but that should be regarded as a primer, not something definitive?

Unfortunately most books that mention soviet engines in any detail not only disagree with each other but with themselves depending on page and paragraph.

The P-185 fighter From wiki: "However, flight testing was interrupted by the need to replace the engine between 17 December 1942 and 26 January 1943. The new engine failed the next day and the aircraft crashed on 27 January. Flight tests were ordered to be continued with the original prototypes to validate the range figures, but the first prototype crashed on 5 April, killing the pilot as he attempted a dead-stick landing"

This was about the 4th forced landing/crash caused by the M-71 engine and this is 1 1/2 years after the engine was first flown. Granted things were disrupted by the German invasion but it was this last crash that ended production plans for the P-185 and the M-71 engine, not a lack of production space.

There is a lot "iffy" information. I would grant that the M-82 had higher priority for production than the M-71 but then the M-82 actually worked. The Russians were between a rock and hard place. They needed higher performing engines but they also needed engines that worked. Had a higher powered engine been available that had the same reliability as the lower powered engine I have little doubt the Russians would have switched over one factory. At least in any but the most desperate of times. This story about no factory space until mid 1944 or later has a certain smell about it considering the number of prototypes they were fooling around with, both engines and aircraft. The M-82 and the M-70/73 series are from the same design bureau. A bit like Wright and the R-2600 and the R-3350. (more than a bit as the Russian engines were based off the Wright Cyclone).

Going back to the M-105 series. At some point the Russians built 150 M-106s in 3 months ( see the AEHS articular for how long it took an American factory to reach it's 150th engine) a number of YAK -1s were fitted with these engines but little or no flying was done before the engines were pulled and replaced by M-105s.