M-82 / M-105 engines

[WTE_Galway]

Originally Posted by 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?

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]

Originally Posted by 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/eng...tem-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]

Originally Posted by JtD

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]

Originally Posted by WTE_Galway

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.