Cooling required?

[David Ramsden]

I'm new to this. Advice please!
Just about to install a Rimfire 400, 30A esc, and 1600mah Lipo in the nose of a Kloudrider (balsa glider) I'm building. I've heard that motors escs and batteries can get hot but I can't find any guidance on how much ventilation they need nor how to provide it. Is it okay to surround the motor in balsa? Is it okay to pack the battery & esc in with foam?
Thanks,
David

[Richard Clark 2]

Welcome. I'm fairly new here too but not new to model planes (maybe you aren't either) or electrics. I was somewhat reluctant to reply as in all forums of any sort you may get lots of replies, all different.

However, here's how I do it.

Do NOT 'embed' the motor in a block of balsa. Mount it via its mounting holes in a 'clear' space. Put a hole in the front or front underside to let air in and long enough to let air out, or better, another hole in the next bulkhead to let air into the rest of the fuselage .

Just let the ESC hang on its wires in a space big enough to let air pass by but not so big that it can fall about all over the place. They are usually rugged enough that they don't need any foam protection.

A bit of thin foam on the fuselage sides to loosely hold the battery. Do not stick foam on the battery itself. A secure structure in front and behind the battery to secure it longitudinally in the desired place, ideally so the  the C of G is right. Maybe with a little foam at the front. SECURELY mount the battery with a Velcro strap and a hatch to access it, you don't want to have to take the wing off every time.

A hole behind to let air out.

Ideally buy a 'wattmeter' but if not measure how hot the motor gets with a couple of fingers. 'Warm but not hot' is fine.

Edited By Richard Clark 2 on 10/06/2020 01:10:59

[Nigel R]

Much as Richard says.

Some air needs to get in.

Some air needs to get out.

Motor and esc must be twixt the two.

I would not trust one single long hole to achieve that personally. Two holes will encourage the desired situation. A scoop on the inlet even more so. A reverse scoop on the out hole further improves.

[Frank Skilbeck]

I have a similar sized balsa electric glider, the motor is a snug fit in the nose and the ESC sits alongside the battery. There's some air inlet holes behind the spinner and an outlet under the wing (where the receiver fits). It's all quite tight, but it's a glider so the motor only runs to thermal hunting height, so the motor tends to do a 30 second run and then glide for 2+ mins (depending on the thermals).

So while I agree you don't want to pack the ESC in foam etc don't get too hung up on multiple air inlets and outlets on a glider, yes if this is a sports/aerobatic/scale power plane but on a glider the motor is only used for a few seconds in bursts so doesn't have much time to heat up and plenty of time to cool down.

[Dad_flyer]

You don't want to wrap up anything as that will keep the heat in, but as Frank says a glider is not a big power model and does not need so much cooling.

I have a second hand ARTF E-Fair glider. There are basically no cooling inlet or outlet holes designed and everything is pretty close fit in a glider. I am not a good thermal hunter, so the motor runs a lot, but nothing gets hot as it is not a high power system. In the end keep an eye on it for the first (short) flight. Is anything more than warm when it comes down?

[David Ramsden]

Thank you Richard, Nigel, Frank, and 'Dad_flyer'. That all sounds like great advice which I shall follow.
David