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Old Oct 30, 2012, 07:34 AM
Brutus1967 is online now
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I convince things to work
The Netherlands
Joined Nov 2009
4,620 Posts
Well.... the load is different (probably higher) and the problem is a little bit that with airplane use the amount of cooling air is virtually unlimited and the speed at which it is flowing past the engine is load dependent.

In a helicopter it is running at a constant RPM over the whole range, so cooling effect does not change, but load does.

The engine is also not designed to be in a duct, so the cooling fin arrangement is not optimal as well.
I guess it is a bit equal to having the engine in a too restrictive cowling.

2 strokes usually work OK in the same duct (the original design is for a 2 stroke) but those are usually fitted with a heat-sink, and the fan is running 14000~15000 RPM. No real good possibilities to fit a heat-sink on a fourstroke, and the fan is only doing 11000 RPM....

The biggest factor however, is that the fan is drawing air over the engine, and the air then tends to be less turbulent compared to a fan blowing over the engine, thus heat absorption is most likely not as effective as well

But I am looking into possibilities to improve cooling without spending power on a bigger fan, as it seems that is the way to go now.

It is all a bit on the limit of what's possible, actually....

Brgds, Bert
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Last edited by Brutus1967; Oct 30, 2012 at 07:39 AM.
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