Yakmovik anyone?

[Clay_Allison]

I was researching the Soviet Aircraft of the Great Patriotic War and I was amazed at the performance stats for the AM-38 compared to the Klimov engine, which was based on the biggest dissapointent of the entire war, the H.S.12.

So here was an engine that was underpowered, flying somewhat heavy LaGGs and Yak-1s. It just seems like a recipe for disaster, no wonder they were shot down in such numbers.

If a Yakovlev or LaGG had been designed to incorporate the AM-38 and the Klimov factories had been shifted to it (concentrating all Russian V-engines on a single model) could the plywood fighters of the early war been more competitive?

[HellToupee]

probly because the am-38 had a massive displacement it was much bigger than a vk-105 and 107. The engine was not that bad, the vk105 and 107 compares well power wise with DBs, they didn't have high quality fuels like the western allies.

[Clay_Allison]

Yeah, it was 600 pounds and 10L more displacement, but the power to weight ratio for the AM-38 was better.

Note that I don't think you could take a Yak-1, cut off the nose forward of the firewall and plug in a nose from an Il-2, it would clearly be utterly imbalanced. But if a new design for a Yak-5 (the only number not used in production) had been drafted around the bigger, more powerful powerplant, it could have been a very hot fighter.

[HellToupee]

Power to weight wasnt alot better, you would lose the power to weight gains on a fighter needing to be built stronger to mount the engine. The vk-107 had better power to weight.

Yak-5 was used for a prototype with the vk105.

[Venganza]

Originally Posted by HellToupee

Power to weight wasnt alot better, you would lose the power to weight gains on a fighter needing to be built stronger to mount the engine. The vk-107 had better power to weight.

Yak-5 was used for a prototype with the vk105.

As I understand it, when they put the Klimov VK-107A engine into a Yak to make the Yak-9U, it went like a bat out of Hell. (Don't judge it by its performance in the Korean War, when it was being flown by greenhorn pilots against American pilots with WWII experience.)

Venganza

[Clay_Allison]

Originally Posted by Venganza

As I understand it, when they put the Klimov VK-107A engine into a Yak to make the Yak-9U, it went like a bat out of Hell. (Don't judge it by its performance in the Korean War, when it was being flown by greenhorn pilots against American pilots with WWII experience.)

Venganza

I'm not really talking about the 1945 fighters though. I'm sure the 9U really moved but I think a fighter with more power and a bigger engine would have given the Germans a better account of itself.

[claidemore]

I posted this on another thread, but I'll repost it here as it is pertinant.


Just doing a quick comparison with the AM-38.

The Klimov 105 : 0.89hp/lb, AM38 : 0.94 hp/lb
Klimov weight: 1365 lbs, AM-38 weight: 1940 lbs.
Klimov displacement: 2142 cu/in, AM-38 : 2847 cu/ins.
Klimov supercharger: single stage two speed, AM-38: single speed.
Klimov 2600 rpm takeoff: AM-38 2350rpm.

The Klimov was lighter, had higher rpm, higher compression ratio, better supercharger.

They built over 90,000 of the M-105s. For the lightweight Soviet fighter designs like the Yak, it seems ideally suited. (later in the war they were designated VK instead of M, to recognize the head designer at Klimov)

BTW, the Yak 5 was a testbed for the high alt Klimov M-105PD (D stands for Dollezhal, the two stage supercharger that gave them development problems). The Yak 5 was flown at over 12000 meters and 650 km/h at 8500 m in 1942. Development was halted because there was no perceived need for high alt planes. The Mig 3 had excellent high alt performance, and had already proven to be less than successfull in the primarily low alt tactical air fighting on the Eastern Front.

[Clay_Allison]

Originally Posted by claidemore

I posted this on another thread, but I'll repost it here as it is pertinant.


Just doing a quick comparison with the AM-38.

The Klimov 105 : 0.89hp/lb, AM38 : 0.94 hp/lb
Klimov weight: 1365 lbs, AM-38 weight: 1940 lbs.
Klimov displacement: 2142 cu/in, AM-38 : 2847 cu/ins.
Klimov supercharger: single stage two speed, AM-38: single speed.
Klimov 2600 rpm takeoff: AM-38 2350rpm.

The Klimov was lighter, had higher rpm, higher compression ratio, better supercharger.

They built over 90,000 of the M-105s. For the lightweight Soviet fighter designs like the Yak, it seems ideally suited. (later in the war they were designated VK instead of M, to recognize the head designer at Klimov)

BTW, the Yak 5 was a testbed for the high alt Klimov M-105PD (D stands for Dollezhal, the two stage supercharger that gave them development problems). The Yak 5 was flown at over 12000 meters and 650 km/h at 8500 m in 1942. Development was halted because there was no perceived need for high alt planes. The Mig 3 had excellent high alt performance, and had already proven to be less than successfull in the primarily low alt tactical air fighting on the Eastern Front.

I responded in another thread as well, but. Basically I belive that it's worth balancing a larger engine in a lighter plane as long as the engine is efficient.

A greater power/weight ratio tells me that putting a bigger engine on is pure profit.

I believe in putting biggest most powerful engine in a light package and fighting on the boom and zoom.

EDIT: sorry about the typos, it was really late and I was tired.

[claidemore]

Originally Posted by Clay_Allison

I rwesponded in another thread as well, but. Basically I belive that it's worth balancking a larger engine in a lighter plane as long as the engine is efficient.

A greater power/weight ratio tells me that putting a bigger engine on is pure profit.

I believe in putting biggest most powerful engine in a light package and fighting on the boom and zoom.

Yup, agree with the concept completely.

In the case of the Mikulin AM-38 other factors came into play besides power/weight ratio.
Production limitations, availablility, and need in other aircraft.
Basically they needed them in the IL2. At one point the factories were still making some AM-35s for Migs, and Stalin issued a rather harsh letter. That was it for AM-35s (and the Mig) and after that they made only AM-38s and the IL2s got all of them.
Eventually they tried a AM-38F in the I-220 but only a couple of prototypes were made. Supposedly a few Mig 3's had AM-38s installed in the field as well. Actually the AM-39 might have been a better choice, with superior high alt performance.

To switch factories that were producing Klimovs to AM-35/38s would have created needless costs and delays in production.

One thing that mystifies me, is that the H.S. 12 was designed and reputed to be relatively 'leakproof', yet the Klimov M-105 had a reputation for being 'leaky'. Not sure, but this could have been due to the re-design to make it suitable for colder weather in Soviet service.

[Clay_Allison]

Originally Posted by claidemore

Yup, agree with the concept completely.

In the case of the Mikulin AM-38 other factors came into play besides power/weight ratio.
Production limitations, availablility, and need in other aircraft.
Basically they needed them in the IL2. At one point the factories were still making some AM-35s for Migs, and Stalin issued a rather harsh letter. That was it for AM-35s (and the Mig) and after that they made only AM-38s and the IL2s got all of them.
Eventually they tried a AM-38F in the I-220 but only a couple of prototypes were made. Supposedly a few Mig 3's had AM-38s installed in the field as well. Actually the AM-39 might have been a better choice, with superior high alt performance.

To switch factories that were producing Klimovs to AM-35/38s would have created needless costs and delays in production.

One thing that mystifies me, is that the H.S. 12 was designed and reputed to be relatively 'leakproof', yet the Klimov M-105 had a reputation for being 'leaky'. Not sure, but this could have been due to the re-design to make it suitable for colder weather in Soviet service.

Stalin was as bad as Hitler for interfering when he shoudn't have. He didn't back off until it was clear that he needed to trust Zhukov or lose the war.

He loved Sturmoviks the way Hitler loved the Stuka, and neither plane was self-defending unescorted.

In retrospect, perhaps a MiG-3 with an AM-38 rather than the AM-35 would have been the best of all soviet fighter worlds. It would have been worth it to make 4/5 as many Il-2s if you had a companion fighter to escort them.

[HellToupee]

Neither were supposed to be self defending, they were specialised planes that excelled when used correctly. Il2 was a dedicated CAS fighter a concept still relevant today.

Producing mig-3s with AM-38s would have been a waste, it was just unsuitable being a high alt fighter where most fighting was at low alts. The greater power to weight ratio is small would be lost in the greater airframe weight needed and the drag from its size. It would have been easier for them to produce the vk107 instead which could have been in production as early as 1942.

[claidemore]

There were plenty of fighters to escort the IL2s. The usual practice was for the La5's or P39s to do fighter sweeps or provide top cover, and the Yaks to provide close escort. One of the few examples of close escort being used successfully (relatively).

Don't forget that the AM-38 was a low alt only engine. The Klimov actually had a better supercharger and better performance at medium altitude.
There were Yaks with M-105PFs that intercepted high flying Luftwaffe recon planes successfully, though I don't know how well they would have done against 109s at those alts.

We also have to keep in mind the Soviet doctrine when it came to fighter planes. They wanted lots of planes with a couple weapons per plane, rather than fewer planes with lots of weapons. Understanding that mentality, its not hard to see that they were not willing to lose production numbers to get more powerful engines, (and they were producing as much as they could).
For the Soviets it was total war, every resource, (including human) was stretched to the max. There was no way they were going to take away 1/5 of IL2 production, just to have fighters that could go a few miles per hour faster.
Production limitations were one of the reasons the VK-107 wasn't produced earlier in the war, overheating problems the other.

[Clay_Allison]

Originally Posted by HellToupee

Neither were supposed to be self defending, they were specialised planes that excelled when used correctly. Il2 was a dedicated CAS fighter a concept still relevant today.

Producing mig-3s with AM-38s would have been a waste, it was just unsuitable being a high alt fighter where most fighting was at low alts. The greater power to weight ratio is small would be lost in the greater airframe weight needed and the drag from its size. It would have been easier for them to produce the vk107 instead which could have been in production as early as 1942.

The MiG-3 was only a high-alt fighter because the AM-35 was a high alt engine. The AM-38 was the same engine block, almost exactly the same engine as the AM-35 except it was optimized for low alt for the Il-2. What airframe weight are you talking about? It only weighed 100 pounds more total. It would be less than changing out a DB 601 for a DB 605.

[Clay_Allison]

Originally Posted by claidemore

There were plenty of fighters to escort the IL2s. The usual practice was for the La5's or P39s to do fighter sweeps or provide top cover, and the Yaks to provide close escort. One of the few examples of close escort being used successfully (relatively).

Don't forget that the AM-38 was a low alt only engine. The Klimov actually had a better supercharger and better performance at medium altitude.
There were Yaks with M-105PFs that intercepted high flying Luftwaffe recon planes successfully, though I don't know how well they would have done against 109s at those alts.

We also have to keep in mind the Soviet doctrine when it came to fighter planes. They wanted lots of planes with a couple weapons per plane, rather than fewer planes with lots of weapons. Understanding that mentality, its not hard to see that they were not willing to lose production numbers to get more powerful engines, (and they were producing as much as they could).
For the Soviets it was total war, every resource, (including human) was stretched to the max. There was no way they were going to take away 1/5 of IL2 production, just to have fighters that could go a few miles per hour faster.
Production limitations were one of the reasons the VK-107 wasn't produced earlier in the war, overheating problems the other.

yeah, if it wasn't for the P-39, maybe I have more of a point, maybe they should have just asked the US to leand least them a boat full of Allison V-1710.

[Von Frag]

Why do you say the Hispano Suiza was a dog? Surely the main French fighters of the war only had 860 h.p. (MS-406) or 920 h.p. (DE-520) but the French had HS engines testing out at 1,600 hp to power a version of the 520 BEFORE the collapse. Allison did not get the 1710 to this horsepower until 43 or 44. So don't blame the engine, blame the govt. that did not have the forethought to take full advantage of the engines potential.