Interesting little detail about the AM-38

[Finkeren]

Just a short video I stumbled upon explaining the IL-2’s engine’s unique throttle:

 

 

Maybe some of you will find it interesting.

[Ehret]

So, it decompress surplus air from the compressor acting kind of an inter-cooler at very low (ground level basically) altitude. Helpful indeed but obsolete when compared to fluid-coupled superchargers and engines with (like the Merlin) proper inter-coolers.

Edited July 7, 2018 by Ehret

[danielprates]

Did I understand correctly? Instead of a butterfly-type admisison control,  the system used a fan-type part, whose blades would change pitch to match the ideal config for a given altitude? Or that difference in admission would be regulated by how fast/slow the fan turned?

[Ehret]

24 minutes ago, danielprates said:

Did I understand correctly? Instead of a butterfly-type admisison control,  the system used a fan-type part, whose blades would change pitch to match the ideal config for a given altitude? Or that difference in admission would be regulated by how fast/slow the fan turned?

 

No as I can understand - there are spiral like guides between the compressor and waste-out. It acts like a turbine but it's the surplus compressed air which starts to swivel and decompress. The final effect is reduced drag in the compressor and reduced temperature of intake air. It works at low alt only.

Edited July 7, 2018 by Ehret

[danielprates]

So the blades are fixed then. I thought it would be too sophisticated to have pitch-adjusting blades.

[Art-J]

9 hours ago, danielprates said:

So the blades are fixed then. I thought it would be too sophisticated to have pitch-adjusting blades.

 

No, your previous post and interpretation is right, while Ehret is incorrect. These were viariable vanes located on the inlet to the impeller (as shown in the video indeed). You can watch some more detailed drawings of this device on AM-38, AM-42 and Jumo 213 here:
https://ww2aircraft.net/forum/threads/on-superchargers-mikulins-klimovs-jumos-etc.40086/

Edited July 7, 2018 by Art-J

[danielprates]

1 hour ago, Art-J said:

 

No, your previous post and interpretation is right, while Ehret is incorrect. These were viariable vanes located on the inlet to the impeller (as shown in the video indeed). You can watch some more detailed drawings of this device on AM-38, AM-42 and Jumo 213 here:
https://ww2aircraft.net/forum/threads/on-superchargers-mikulins-klimovs-jumos-etc.40086/

 

Ah. That makes more sense,  but indeed I found it hard to beleive at first,  and indeed prefered to think that I wasn't getting it right. That because, a variable-pitch bladed fan was not an easy thing to make,  and when it comes to things soviet,  there is that inclination to presume they always went with the brute,  course choice. I'm actually quite amazed at how this worked.