By the way, if your model is one of today's Chinese ARFs, chances are better than even it won't have ANY heat exhaust opening at all anywhere. Why? ....let's not go there.......

The last 4-5 electrics I've had anything to do with certainly had no openings anywhere. And their manuals didn't mention making any.

I just helped a buddy rebuild and recover his Telemaster electric. We used a soldering iron to put two decent sized holes in the bottom aft of the fuselage. I just did the same thing to an EFlite Pitts. And a buddy's EFlite Mini-Edge. It's nice if you can put the openings in negative pressure areas, but for sure, you need openings somewhere. One ARF line of profiles comes with a battery box that completely seals the battery into the sucker. No openings at all. Batteries live longer if they're kept from melting themselves down.

It really hurts to have NO exhaust area.