I am finishing a QQ Python bipe. With an old DA100, PT 27-10 prop and no spinner it is very nose heavy at 85mm behind the bottom wing leading edge and set up on a Southwest Systems EZ balancer from Don's Hobbies. This is with two 7 oz. 2700mAh 5 cell NiMH batteries and Futaba heavy duty switch harnesses on the supplied aft mount, 2 stations behind the cockpit hatch. Also a 5 or 6 oz. Red Aero pilot bust and mount in the cockpit. With either light weight standard mufflers from Troy Built Models or MTW 75 canister mufflers and headers on the DA100 it needs about 12 oz. more under the batts. to balance. That last part surprised me. True fact! Less ballast could be placed further aft but my experience has been this sets off what I call an undesireable pendulum effect in the pitch axis. I could move my DA100 1/2" aft but have been told placing the prop this close (1/4 inch) to a big radial cowl like on a YAK reduces the engine thrust too much. I could switch to a DA100L but the weight difference does not appear to be enough to materially address my problem. I could switch to a DA 85 but I prefer twins in engines this size. If this turns out to be a very good flying plane I will go for the new DA100L.

Have any of you QQ Python flyers out there licked this problem?

I am building the Python for sport flying not competition so I guess I will just throw the lead under the batteries and go fly with the cans since they sound so cool and cost so much.

Anyway, something for you guys to think about if you're considering a Horizon QQ Beast which appears to be very similar to the QQAC Python I've got.

maybe just a few oz of stickey weight right on the tail wheel might work

By all means,, move that engine back 1/2 inch. 1/4 prop to cowl clearance is fine.

fly the plane first and see what it needs. It might suit your flying tastes just the way it is.

Thanks for the replies guys. Experienced Python pilots have advised me that the CG may be further forward than called out by the manual i.e., 63mm from the bottom wing leading edge as opposed to the recommended 85mm which is on the spar of the bottom wing. Come to think of it isn't the spar of a bipe's bottom wing a pretty far aft CG? It is in my experience (Balsa USA 33% Flybaby bipe and Miles Reed 27% Week Solution). Most bipes, if I pick up the plane from the rear center of the top wing and she's a little nose heavy I give it a try.