Please don't use the Minwax Water Based Polyurethane on the outside of your glow airplane.

I have it on the outside of my ducted fan jet and it's a mess. It's NOT fuelproof, in fact, I have exhaust residue areas on the bottom of my plane where it has turned into a slimey mess. The stuff really hasn't hardened, I still get fingerprints in it, even after being outside in the desert >100 deg heat many times. Other crud just likes to stick to it. 409 won't clean up the slime and only paint thinner seems to get it and then the Minwax slime just washes away down to the paint. Any oily reidue on the outside is hard to deal with. I only use 10% nitro in this bird.

On the other hand, I didn't really wax it either so maybe it needs a barrier.

I've tried the Varethane Outdoor gloss without much better results but people tell me the Gloss Floor variety is better. Frankly, I'd go to the auto parts store and try the $3.49 8oz cans of touchup clear before I'd use Minwax on anything again.

Just my $0.02 worth.