Mikulin AM-38 construction

Pasoleati

I really should change my personal text
Joined
Jun 29, 2012
Messages
301
Reaction score
56
Seems that finding construction details is very difficult on this engine. For example, what kind of cylinder liner/block construction did it have?
 

Calum Douglas

Piston engine designer
Senior Member
Joined
Jan 17, 2019
Messages
202
Reaction score
574
Website
www.calum-douglas.com
Its a bit like a cross between a V-1710 and a Merlin. Wet liners, with 2-piece block and crank-axis split crankcase. The heads
are very similar to the V-1710 in terms of valve angle and coolant system layout. In many respects, very modern
and well designed in my view.
1606935451204.png
 
Last edited:

Pasoleati

I really should change my personal text
Joined
Jun 29, 2012
Messages
301
Reaction score
56
Thanks! How are the liners attached? If I remember correctly, the carburettors are between the inlet and the supercharger outlet?
 

Calum Douglas

Piston engine designer
Senior Member
Joined
Jan 17, 2019
Messages
202
Reaction score
574
Website
www.calum-douglas.com
Thanks! How are the liners attached? If I remember correctly, the carburettors are between the inlet and the supercharger outlet?
Photos a bit blurry, but it appears the liners are installed in almost exactly the same was as the 2-piece block Merlin (i.e. "sandwich" top hat) -
but, with a bit of the Allison design thrown in too as it extends UP into the chamber walls a bit like the V1710.
 

Pasoleati

I really should change my personal text
Joined
Jun 29, 2012
Messages
301
Reaction score
56
The reduction gear apparently uses herringbone gears?
 

Pasoleati

I really should change my personal text
Joined
Jun 29, 2012
Messages
301
Reaction score
56
I wonder what improvements were made on the AM-42 over the AM-38? Net sources indicate the AM-42 had a very low compression ratio of 5.5:1...
 

Aurum

ACCESS: Restricted
Joined
Apr 16, 2011
Messages
6
Reaction score
1
I wonder what improvements were made on the AM-42 over the AM-38? Net sources indicate the AM-42 had a very low compression ratio of 5.5:1...
AM-42 had significatly increased boost and revolution. You can see in this table АМ-34-42 data.png
 
Last edited:

tomo pauk

ACCESS: Secret
Joined
May 1, 2011
Messages
322
Reaction score
197
I wonder what improvements were made on the AM-42 over the AM-38? Net sources indicate the AM-42 had a very low compression ratio of 5.5:1...

Better late than never, I guess :)
AM-42 featured a stronger/heavier construction where needed (mostyl crankshaft and crankcase), an improved lubrication system, while the crakshaft was with counterweights. Thus it was possible to increase RPM to 2500. Lower compression ratio allowed for increase of boost. Put together (higher RPM + higher boost), the engine was capable for extra 300 HP vs. AM-38F. However, it took a lot of time for the AM-42 to became service-worthy, Russian-language Wikipedia notes that it took about 18 months of testing and modifications for the engine to pass the 100-hour test.
(we can note that VK-107 engine, that was to power the late-war Yak fighters, was limited to 25 hr in service when introduced)
 

Similar threads

Top