flyrotary@lancaironline.net Mailing List Archive

Al can you mount a separate small rad for the PSRU?

George ( down under)

You mean an additional small cooler to further cool the oil before it goes to the drive? My conclusion was that it is not necessary. There was a typo in my reply below – it was supposed to read “I’ll proceed on without worrying about that outlet temp.” I’ll keep an eye on that temp, but I’m not that concerned as long as it is less than 250F.

I do expect to pursue further measures for making my oil cooler more effective to reduce oil temps.

Figures I found on the web indicates 3% is a fairly standard figure used for a planetary gearbox efficiency.

So 3% of 160 HP = 4.8 HP which is mostly converted to heat.

Tf = 180F + (203/((7.3 *.5) *0.4) = 180F + 69F = 249F

So using this example and assuming I haven't screwed up, I would expect the oil temps coming out of the gear box to be around 249F.

Ed;

I really appreciate when you take the time and effort to do the math that I’m to lazy to do.

I think at the time I noted the re-drive temp out it was 243F, shortly after leveling off from a climb, and the oil temp (after cooler, into drive) was still about 210F. I’m gonna guess the power at that point was about 140 hp. So it seems that the efficiency and/or the flow rate is a bit higher. In any case; I’ll proceed on with worrying about that outlet temp.

Thanks.

BTW; I think that monitoring the redrive outlet is important. It can give you a heads up on problems with the redrive. It is nice to be able to set a limit in the EM to alert you of a potential problem.

Al