Yak-9U vs BF-109G-14

[Laurelix]

Yak-9U
Entered Mass Production in April 1944
Powered by VK-107A Engine: 1500 Horsepower (1.44 ata) / 1650 Horsepower (1.50 ata)
Max Speed: (1.44 ata)
575km/h at Sea Level / (594km/h , 1.5ata)
672km/h at 5000m / (???km/h , 1.5 ata)
Rate of Climb: (1.44 ata)
Time to 5000m: 5:00 / (~4:25 , 1.5 ata)
Wing Loading: 186.88kg/m2
(3205kg loaded / 17.15m2 wings)


:::

BF-109G-14
Entered Mass Production in July 1944
Powered by....
DB-605AM (1.7 ata) - 1775 Horsepower engine or... DB-605ASM (1.7ata) - 1775 Horsepower engine
Max Speed: (DB-605AM, 1.7 ata, MW-50)
573km/h at Sea Level
670km/h at 5000m
Rate of climb: (DB-605AM, 1.7 ata, MW-50)
Time to 5000m: Roughly 4:10
Wing Loading: 194.44kg/m2
(3150kg Loaded, 16.20m2 wing area)

::::

Yak-3 (VK-107A)
Entered Production in early 1945
Powered by VK-107A Engine: 1500 Horsepower (1.44 ata) / 1650 Horsepower (1.50 ata)
Max Speed: (1.44 ata)
600km/h at Sea Level / (620km/h , 1.5ata)
697km/h at 5000m / (???km/h , 1.5ata)
Rate of Climb: (1.44ata)
Time to 5000m: Roughly 4:10
Wing Loading: 197.64kg/m2
(2935kg loaded weight, 14.85m2 wing area)

 

[Dzmitry M]

Ok, there might be quite a bit to sort out in this comparison:
1. Yak-9U did not enter mass production in April 1944, it only got to the "battlefield trial" stage in October-December 1944. ("Battlefield trial" is practically equipping a small number of units with a new aircraft to see how pilots like it, what problems occur in frontline conditions and how effective it really is against the enemy). In April 1944 Yak-9M appeared, and that was just a refined Yak-9 with VK-105PF (adopted PF2 around autumn 1944), 4-tank wing from Yak-9D and a fuselage from Yak-9T. It had some Quality of Life improvements like automatic water radiator or jettisonable(?) canopy, but performance-wise it was the same as the 1943 Yak-9. And in May 1944 Yak-3 appeared, which only became operational with first frontline units in July 1944.
2. Yak-3 VK-107 never entered production, it was a testbed aircraft made to see how much potential there even was in such a fighter. A single aircraft was made, rumored to have gotten to 700-720 kmph at altitude, and then the idea was abandoned in favour of new jet fighters. Not to mention that it only flew after the war, surely not in early 1945.

 

[GrauGeist]

Perhaps compare the performance of the YaK-9U to the Bf109K-4?

 

[Dzmitry M]

Perhaps compare the performance of the YaK-9U to the Bf109K-4?

Yeah, that would be a more realistic comparison

 

[bf109xxl]

Ok, there might be quite a bit to sort out in this comparison:
1. Yak-9U did not enter mass production in April 1944, it only got to the "battlefield trial" stage in October-December 1944.

According to the book "Yak Fighters of the Great Patriotic War" by A.T. Stepanets (he was a leading engineer at the Air Force Research Institute during the war), serial production of the Yak-9U began in April 1944, immediately after the end of state tests on April 20, 1944 (according to Yakubovich - April 27), although the "frontline" tests took place in October-December 1944. According to Yakubovich, the contract for delivery of the Yak-9U was signed only in August 1944, although the first 11 serial Yak-9U were assembled at Omsk plant #166 as early as February (!) 1944. The first production batches had serious engine cooling problems, as a result engine speeds were limited to 2800 min-1​ during climb and 3000 min-1​ in level flight. The ground speed was reduced by 25 km/h and the maximum speed by 64 km/h. The time to reach an altitude of 5000 m was increased by almost a minute. According to Stepanets, the major defects were fixed by December 1944, although actual control tests in January (plant #166) and February (plant #82) 1945 demonstrated that the airplane still did not meet the requirements of the Air Force. The test data for the Yak-9U prototype aircraft do not reflect the performance of the production aircraft.

 

[Dzmitry M]

According to the book "Yak Fighters of the Great Patriotic War" by A.T. Stepanets (he was a leading engineer at the Air Force Research Institute during the war), serial production of the Yak-9U began in April 1944, immediately after the end of state tests on April 20, 1944 (according to Yakubovich - April 27), although the "frontline" tests took place in October-December 1944. According to Yakubovich, the contract for delivery of the Yak-9U was signed only in August 1944, although the first 11 serial Yak-9U were assembled at Omsk plant #166 as early as February (!) 1944. The first production batches had serious engine cooling problems, as a result engine speeds were limited to 2800 min-1​ during climb and 3000 min-1​ in level flight. The ground speed was reduced by 25 km/h and the maximum speed by 64 km/h. The time to reach an altitude of 5000 m was increased by almost a minute. According to Stepanets, the major defects were fixed by December 1944, although actual control tests in January (plant #166) and February (plant #82) 1945 demonstrated that the airplane still did not meet the requirements of the Air Force. The test data for the Yak-9U prototype aircraft do not reflect the performance of the production aircraft.

Thanks for the correction, I've relied on Stepanets' book too in fact. Although to be frank I really forgot the discrepancy in Yak-9U's case between the start of production and its use on the frontline. Guess I just went to remember only one of the dates, and that one's of frontline trials, since Yak-9U's been tested since 1943. But well, VK-107 was a steaming pile of malfunctions, and the rest of the story you've already mentioned. That's why I in general don't have that good of an impression with the VK-107 powered fighters.

 

[bf109xxl]

Thanks for the correction, I've relied on Stepanets' book too in fact. Although to be frank I really forgot the discrepancy in Yak-9U's case between the start of production and its use on the frontline. Guess I just went to remember only one of the dates, and that one's of frontline trials, since Yak-9U's been tested since 1943. But well, VK-107 was a steaming pile of malfunctions, and the rest of the story you've already mentioned. That's why I in general don't have that good of an impression with the VK-107 powered fighters.

I have the impression that the Yak-9U was Yakovlev's big failure - if he had not been Stalin's favorite and Deputy Commissar of Aviation Industry, the whole Yak-9U story could have been the end of his career. Yakovlev walked a razor blade with eyewash, forgery and manipulation during the prototype trials. The Yak-9U was _never_ brought to acceptable conditions, and not all the problems can be attributed to the VK-107A - during the rearmament of the 139 GIAP in the summer of 1944, the VK-107A engines averaged 115 hours, which exceeded the warranty (100 h). It was Yakovlev's fault that he was unable to provide the required cooling. In the spring of 1946, 2267(!!!) Yak-9U were removed from service due to design and manufacturing defects. And in general, more than 4800(!!!) fighters of wooden and mixed construction were written off at that time. Serial production of fully or partially metal Yak-9U (Yak-9P) can be explained only by the fact that in 1946 there were no real alternatives - La-9/-11 were not mass produced yet.

 

[Dzmitry M]

I have the impression that the Yak-9U was Yakovlev's big failure - if he had not been Stalin's favorite and Deputy Commissar of Aviation Industry, the whole Yak-9U story could have been the end of his career.

That I disagree with. After all practically every noticeable Soviet aircraft designer bet on a faulty engine at least once:
1) Yakovlev wasted time and effort on Yak-9U, but still produced the widespread (over 4000 built in a year) Yak-9M and high-performance Yak-3.
2) Lavochkin spent the entire year of 1941 designing LaGG-3 modifications to adopt high-altitude M-105 version or M-107 while literally everyone else were ordered to design their aircrafts to fit the unused M-82 engine (Sukhoi, Yakovlev, Polikarpov, Tupolev, Ilyushin, Mikoyan, Gudkov - the list might go on, but these are who I'm certain about).
3) Speaking of Polikarpov, he's the only case of an aircraft designer specifically ending his career by betting on a bad engine: he stagnated trials of I-185 with M-82 engine because he was certain M-71 would be finished soon enough and show much better results. As you likely know, M-71 did not in fact get finished soon. And by the time Polikarpov was practically forced to provide full trial data on I-185 M-82, the compatible in performance La-5 was already being produced, with F and FN models soon to appear in units.

The Yak-9U was _never_ brought to acceptable conditions, and not all the problems can be attributed to the VK-107A - during the rearmament of the 139 GIAP in the summer of 1944, the VK-107A engines averaged 115 hours, which exceeded the warranty (100 h). It was Yakovlev's fault that he was unable to provide the required cooling.

Here I'll simply quote Stepanets, managed to find his Yak bible in an acceptable format.

On serial aircraft manufactured in December 1944 and later, the main part of the defects of the experimental and first serial aircraft was eliminated. New water and oil radiators were installed (types 728 and 726, respectively) and the flow sections of the radiator tunnels were increased (the height of the water radiator tunnel was increased at the inlet to 300 mm and at the outlet to 100 mm), as a result of which the temperature regime of the propeller-engine group was significantly improved and in all engine operating modes, including the combat power mode (3200 rpm), was practically within the permissible limits.

 

[bf109xxl]

That I disagree with. After all practically every noticeable Soviet aircraft designer bet on a faulty engine at least once:

And how many Soviet aircraft designers could afford to deceive the country's leadership by conducting state tests of an airplane that did not correspond its declared (in official documents!) technical condition (armament removed, etc.)? I will emphasize once again: by the time the VK-107A was installed on the Yak-9, the problem was not in the engine, but in the cooling system, which was designed by the aviation engineers for a given engine performance.

1) Yakovlev wasted time and effort on Yak-9U, but still produced the widespread (over 4000 built in a year) Yak-9M and high-performance Yak-3.

There's no arguing with that. But we were only talking about the Yak-9U. The engine itself was not so bad - it had already been refined on Tomashevich's "110" airplane. Yakovlev had only to optimize the cooling system taking into account the engine requirements, but he failed in this work. The "champion" in "running-in" of completely new and unfinished motors was obviously Polikarpov.

2) Lavochkin spent the entire year of 1941 designing LaGG-3 modifications to adopt high-altitude M-105 version or M-107 while literally everyone else were ordered to design their aircrafts to fit the unused M-82 engine (Sukhoi, Yakovlev, Polikarpov, Tupolev, Ilyushin, Mikoyan, Gudkov - the list might go on, but these are who I'm certain about).

Lavochkin had much to do besides installing the M-107 - the number of design and manufacturing defects of the LaGG was enormous. But Gudkov already in August 1941 installed M-82 on the LaGG - the performance of the Gu-82 was lower than that of the I-185M-82, but still much better than those of the LaGG. As a result, the production of the Gu-82 could be established in early 1942. Usually Lavochkin is portrayed as a very polite and intelligent man, but in the story with Gudkov he showed himself as a cynical schemer.

3) Speaking of Polikarpov, he's the only case of an aircraft designer specifically ending his career by betting on a bad engine: he stagnated trials of I-185 with M-82 engine because he was certain M-71 would be finished soon enough and show much better results. As you likely know, M-71 did not in fact get finished soon.

Initially, there were no more problems with the M-71 than with the M-82, it was just that Shvetsov did not have enough staff to finish the two engines at the same time, and the NKAP (People's Commissariat of Aviation Industry) had an opinion that a smaller and less powerful engine should be easier to finish - it was a mistake.

And by the time Polikarpov was practically forced to provide full trial data on I-185 M-82, the compatible in performance La-5 was already being produced, with F and FN models soon to appear in units.

There were TWO different I-185s with M-82s. The first was with the I-185M-71 fuselage, the second was with a fuselage specially designed for the M-82 (the "I" aircraft).
The I-185M-82 "first" was tested in 1941, and it was on it that the M-82 was brought to a more or less acceptable level. Lavochkin received already an improved motor.
The I-185M-82A "I" had a significantly better flight performance than the La-5F with a more powerful engine. The La-5 was more or less finalized only by the end of 1943, and some shortcomings (heat in the cockpit) were never sufficiently eliminated.
The I-185M-82A was superior to the La-5F in almost all the characteristics (equal only by ground speed), but because of the stupidity of the Soviet leadership, which first forced plant #21 to change the technology to produce a wooden airplane (while the I-16 that was produced had a mixed construction with a large metal share - 40% of the wing skin was of metal), after which it would be necessary to change all the tooling again - in war conditions, this meant an unacceptable production decrease.
The plant in Tbilisi could produce the I-185 (some troubles with manufacturing quality were possible). But the Soviet tradition of winning by quantity did not allow to reach an optimal decision here as well.

Here I'll simply quote Stepanets, managed to find his Yak bible in an acceptable format.

Unfortunately, Stepanects pointed out not all the difficulties with the Yak-9U. Some more information could be found in the book by Yakubovich (not my favorite author, indeed) - ALL control tests (and even the state trials!!!) after all improvements to the Yak-9U design failed.

PS. Are you from Belarus?

 

[Laurelix]

Yeah, that would be a more realistic comparison

G-10