Just finishing my 4*40 and the plans show balancing the aircraft somewhere on the bottom spar. I had heard that you should balance a low wing plane upside down. My plane seems to balance differently from the top spar than the bottom spar. Can someone please clarify how I need to balance the plane. Thanks.

balance it upside down an on the spar at the fuse

That would be correct. You should have a range for the cg. Usually, I set my planes up a little nose heavy for the first flight. Just remember: Nose heavy airplanes fly forever, tail heavy airplanes fly once.

I balanced mine right side up. Flew it for 1 1/2 years nose heavy, seemed to fly good. Then I thought I would experiment and move lots of stuff around. This moved balance point about 1/4" behind spar. Now I broke a prop every time I landed. It seemed to come in nose high, not want to come down, then stall and bang down. So then I moved the CG to just behind spar, now this is flying! Lands great, knife-edge the length of the field. Inverted flight much better, snap rolls look violent. I've got a ST 51 mounted inverted. APC 11x5 or 12x4 works great. 12.25 x3.75 gives awesome thrust and UNLIMITED vertical. This plane is so much fun. I need to get that Venus put together. Have fun, Mike

Chop a bay of the end of each wing and then watch what it will do