M-82 / M-105 engines

[JG52Karaya]

Hello everybody,

Here's a few questions for the experts at hand:

I keep reading that all M-105 engines had ordinary carburettors and thus suffered from neg. G cutouts and that the VK-107 was the only operational Klimov engine with fuel injection. Same for the early M-82 engines (M-82A and M-82F found on the La-5 and La-5F).

So, should all Yaks (excluding the Yak-3 VK107 and Yak-9U) and LaGGs as well as the La-5 & La-5F suffer from neg G cutouts as we see them on the early Spitfires now?

[Zorin]

If this should be true I would like TD to put this on the top of their to-do list.

Souldn't be to hard as they can draw heavily from the I-16 engine cut-out code and the new early Merlin code.

[WTE_Galway]

Hello everybody,

Here's a few questions for the experts at hand:

I keep reading that all M-105 engines had ordinary carburettors and thus suffered from neg. G cutouts and that the VK-107 was the only operational Klimov engine with fuel injection. Same for the early M-82 engines (M-82A and M-82F found on the La-5 and La-5F).

So, should all Yaks (excluding the Yak-3 VK107 and Yak-9U) and LaGGs as well as the La-5 & La-5F suffer from neg G cutouts as we see them on the early Spitfires now?


True for very early 1939/1940 aircraft such as the very first Yak 1's as these were equipped with the M-105P.

From the M-105PA (1940/1941) onwards a new carburetor (without a float chamber) was used avoiding the negative G problem.

[Zorin]

Another thing, the US radials. Why don't they suffer from the same cutout as the Gnome-Rhône engines? They use the same Stromberg carburetor so there should be no difference in fuel injection, right?

[Zorin]

Another thing, the US radials. Why don't they suffer from the same cutout as the Gnome-Rhône engines? They use the same Stromberg carburetor so there should be no difference in fuel injection, right?

Question solved, partially. The Stromberg system prevented the cutout, but why do the Gnome-Rhône engines with the same carb have it?
http://www.ww2aircraft.net/forum/engines/stromberg-pressure-injection-system-14815.html

[Voyager]

From looking at the thread it sounds like there were two types of Stromberg carbs, one with the pressure injection system that was used on most of the engines 1800 in^3 and up, and a float carb version that was used on most of the smaller engines. My guess is that the Gnome-Rhône engines used the float version, and the US versions used the pressure injection system.

As I understand in, the US Navy selected their fighters heavily for acrobatic performance*, so inverted flight was a high priority for them. Both the Spitfire and Merlin engine, on the other hand, evolved out of racing, where inverted flight wasn't a typical mode, so inverted flight systems could easily have been over looked. There is actually a lot of design work that goes into making a plane fully inverted capable, and not all of it is thing that you'd think of right off the bat.

*This was the reason the Brewster Buffalo was initially chosen over the Wildcat, and why the Wildcat had the crazy riveted construction it did. Yes, the unloaded Buffalo, with its one piece wing was more acrobatic than the Wildcat.

[JtD]

Is it correct that all the I-16 engines cut out under negative g?

[WTE_Galway]

Is it correct that all the I-16 engines cut out under negative g?

Some did some did not.

The I16 types I and IV used the Shvetsov M-22 which was a license built Bristol Jupiter (forerunner to the Pegasus and Mercury). Carburetors included the Bristol Triplex and some variants would likely have had negative G issues. Certainly the Bristol Mercury engines fitted to the Gladiators were unhappy under negative G.

Apparently the types 5, 6 10 and 17 were fitted with Shvetsov M25 and usually used a K25 solex carb. The M25 was a licence built copy of the Wright Cyclone R1820-F3. I don't recall hearing about the R1820-F3 ever having neg G problems in US use.

Types 18, 24 and 27 used the Shvetsov M62 an improved M25 and hence was also a Wright Cyclone R1820-F3 derivative and unlikely to have neg G issues.

The M62 was further developed as the M63 and fitted to types 24, 28, 29 and 30 The M62 was once again a Wright Cyclone R1820-F3 derivative.

[Zorin]

Some did some did not.

The I16 types I and IV used the Shvetsov M-22 which was a license built Bristol Jupiter (forerunner to the Pegasus and Mercury). Carburetors included the Bristol Triplex and some variants would likely have had negative G issues. Certainly the Bristol Mercury engines fitted to the Gladiators were unhappy under negative G.

Apparently the types 5, 6 10 and 17 were fitted with Shvetsov M25 and usually used a K25 solex carb. The M25 was a licence built copy of the Wright Cyclone R1820-F3. I don't recall hearing about the R1820-F3 ever having neg G problems in US use.

Types 18, 24 and 27 used the Shvetsov M62 an improved M25 and hence was also a Wright Cyclone R1820-F3 derivative and unlikely to have neg G issues.

The M62 was further developed as the M63 and fitted to types 24, 28, 29 and 30 The M62 was once again a Wright Cyclone R1820-F3 derivative.

Just because the engine was license built does not mean that the carburetor was. It is a seperate and interchangeable part and therefor could have been easily replaced by a domestic one.

[SaQSoN]

Engines M-25, M-25В, М-62, М-63 and М-82А were equipped with float carburetor АК-25-4ДФ or К-25-4Д. Some M-63 were equipped with float-less АК-63.

M-82Ф was equipped with float-less carburetor, М-82ФН - with direct injection system.

M-105 since 1940 were equipped with floatless carburetor К-105БП

PS Most of this devices were designed by Fedor Amosovich Korotkov and his design crew. After the war, with the rise of the jet era, he switched to jet engine fuel feed systems and his designs were again used in most Soviet jet engines until late 1980.

[JtD]

But the K25 carburettor was pretty advanced for its time and for instance had automatic mixture adjustment. I tend to agree with Galway that it is unlikely the later I-16's suffered from neg g cutout, but one would have to be sure.

The K25 was also used with the M62/M63 engines, as was the K63 (AK-25-4DF and AK-63-TK). The technical descriptions of these carburettors, as far as I could find them, made no statement regarding the working principle (float or no float) or about behaviour under negative g.
---
OK, thanks SaQSoN.

[SaQSoN]

The technical descriptions of these carburettors, made no statement regarding the working principle (float or no float).

K-25-4 family was all float, that's for sure.

[JG52Karaya]

Thanks everybody for your constructive posts,

I still have one more question, namely what the situation was on the AM-35/-38 engine family used on the MiG-3 and IL-2. Did these have float, floatless or injection type carbs!?

[SaQSoN]

I still have one more question, namely what the situation was on the AM-35/-38 engine family used on the MiG-3 and IL-2. Did these have float, floatless or injection type carbs!?

Floatless carb.

[bugmenot]

Hi SaQSoN, can you translate this?

Решением ЦК ВКП(б) и СНК СССР от 26 декабря 1940 г. завод № 24 получил указание с апреля 1941 г. выпускать моторы АМ-35А с карбюраторами беспоплавкового типа. Такие карбюраторы были изготовлены, проверены в наземных и летных условиях. Но моторы с беспоплавковыми карбюраторами не были взаимозаменяемыми с обычными AM—35A, внедрение их требовало переделки некоторых узлов двигателя, а также посадочных узлов и капотов самого самолета. Несмотря на определенные преимущества беспоплавковых карбюраторов в силу отмеченных причин они не были внедрены в массовую серию, но более десятка машин с такими карбюраторами все же были изготовлены и сданы в строевые части [22].

http://wunderwaffe.narod.ru/WeaponBook/Avia/Mig3/04.htm

[WTE_Galway]

Engines M-25, M-25В, М-62, М-63 and М-82А were equipped with float carburetor АК-25-4ДФ or К-25-4Д. Some M-63 were equipped with float-less АК-63.

M-82Ф was equipped with float-less carburetor, М-82ФН - with direct injection system.

M-105 since 1940 were equipped with floatless carburetor К-105БП

PS Most of this devices were designed by Fedor Amosovich Korotkov and his design crew. After the war, with the rise of the jet era, he switched to jet engine fuel feed systems and his designs were again used in most Soviet jet engines until late 1980.

Thanks, very useful information.

[SaQSoN]

Hi SaQSoN, can you translate this?

In short words, it says, that at 26 Dec. 1940, Soviet government issued an order to produce AM-35 engines with floatless carbs only. However, this order was not obeyed at full. Only some engines were produced with such carbs, while most were equipped with the float carbs.

This made me search more thoroughly through my vast reference library and I actually found there an original manuals for AM-38 and AM-35 engines. According to them, the engine was equipped with 4 float carburettors, installed after the supercharger, each carb. serving 3 cylinders. This carburettors were equipped with special devices, preventing fuel overflow at a negative G, which made those engine fully aerobatic (according to the said manual).