Winter build project: Wolfgang Matt’s ATLAS

It's a tricky one. You could leave it like it is now and hope for the best. If you later find you need more cooling you will have to make some cuts and you might have already fried a motor by then. If you're lucky you will get away with it.

A mixture of luck and judgement means I have hopefully got plenty of cooling...not as much as the Blue Angel, but still a fair bit. A flew with an 11x10 the other day at 72A and the motor was still cool. Not sure how it will cope in the summer but probably fine.

As for the size of cooling holes, from a dim and distant memory, I recall that the exit has to be 3x as big as the entrance. This might mean making a bigger hole at the back, or it could mean making more holes in that spinner unless you can be sure which way the air flows!

What could also help, without affecting the aesthetics, would be to open up some space around the motor. At the moment the warm and insulating balsa is blanketing it quite snugly.

Hi Chris, as Mike says the rule of thumb of making the exit area 3* the intake area has been around in the IC world for some time ( as temperature increase so does volume - Boyles law and all that).

Generally the intake area for an IC engine is designed to concentrate airflow around the cylinder head of the engine which in some case actually requires baffles to restrict and direct airflow to where is needed rather than swirling uselessly around the cowl.

I believe leccy setups are more efficient than IC so you may get away with less exit area and you can always do some bench tests to see how hot the various components are going to get but even so I'd worry less about ascetics and concentrate on getting good airflow where it's needed. No-one else is going to see a couple of extra holes in the fuz.

AlanF wrote: but even so I'd worry less about ascetics and concentrate on getting good airflow where it's needed. No-one else is going to see a couple of extra holes in the fuz.

It's a no brainier for me, no one is going to notice a hole or 2 on the underside, it would look a lot less pretty after a bad landing in the outfield because you fried the motor.

Fair enough, I'll get hacking in the morning :pinch: The more I think about it, there is no point messing about I might as well hollow out as much as I can and then open it up. Anyway I better get a move on as Mike is soon going to be in the air.

Talking of being in the air Mike, how did the Blue Angel perform on the 11x10?

"ascetics" - really! Good grief

I know :blush: I even went for a white spinner because when the time comes to cover the plane I would like to try and recreate something like this:



I'm assuming you meant 'aesthetics' not "ascetics" because I'm not sure how I can abstain from worldly pleasures whilst building this :evil: