It would seem the best way to cool outrunners that have holes in the case on the end that faces the nose ring, would be to bring air in through the spinner and through holes in the backplate. Wondering if anyone has really thought about the optimum design. I can picture internal vanes but perhaps cutting off the nose of the spinner and leaving a big hole would be adequate. Anyone tried anything like this?

Jim O

Lamar Blair uses the Plettenberg which has spinner cooling.Check with him

This is a few ideas Jim..
The first was my test spinner. I then did it on a purple anodized spinner. It works good as far as I can tell.
The second I pulled off someones site at some point.

Now, I have had the idea of having a spinner the has the bolt in the regular spot, the having an area behind it for 1/4" being finned to direct air in. I may still do it at some point. Just haven't done it yet.

My setup is with the Axi.

Chris

how about cutting the tip off a spinner (chuck it in a lathe or drill)

and with a lightened back plate the air will go right in the spinner hole and to the motor

kinda like the plett setup

low budget

might work , I will make on and try this summer on 5330/F3A equipped model

Kevin

I did the first few runs on my Plett Extra 30-10 Evo with a spinner with the front cut off to leave around 3/4 dia. hole. It has a lightened backplate so the air gets through to the front of the motor. The problem is that this spinner even with the lightened backplate was much heavier than my ES Composites carbon one. To cut the front off you need a spinner without the central bolt and this is limiting. I have had a few flights with the uncut carbon cone which still has a lightened backplate and I couldn't measure any difference when temp gunning the motor hold down bolts from inside the fuz. They go into the hottest part of the motor and never got above 50deg C. The ambient wasn't much above 15-16 C when these tests were done so they need to be repeated when it warms up a bit round here.

Malcolm

Another idea that I saw someone do is to use a 1" smaller spinner, which hopefully will bring more cooling to the motor

I use a Dubro spinner nut instead of a big spinner. The standard cowl hole for the spinner is used. This jams the cooling air into the motor for superior cooling, but there are some minor compromises to esthetics but so it goes. The Axi outrunner never even gets hot. Of course there is a large warm air exit at the bottom of the cowl too.

Simple is better.

ciao -rjf

The air exit is probably more important anyway. If you have a good exit, it will suck air into the motor through any little opening you have.

While this is true in theory and probably more so with glow, I have found my outrunners need air direct through the windings. Not just over the can. Otherwise the windings will get too hot. The outside of the can may feel adequate after landing but the windings will be very hot. After the plane has been on the ground for a few minutes feel your can again, it will be hot if your windings aren't getting adequate cooling. It's tough to get air through the windings though on my motor. I run a bigger gap than normal behind the spinner plus other stuff.
But, I will say that with a depron former directing air out of the exit hole I have found it also helps cooling.