Bill,
Getting the CG right has been a struggle and very interesting. Everything on the plane except the front engine is BEHIND the target CG. The tail surfaces are made of 4MM COROPLAS which is very light. I have had to trim even that. Also shortened the tail moment. Also changed from aluminum channel for the booms to aluminum angle. Also had a piece of lead that totaled about 8 inches in length (the type sold for models---don't know # of ounces) mounted with the front engine. After about 30 flights have managed to get rid of all of the lead weight. The CG has moved back about 1-1/2 inch and it still loops OK. Very tolerant in pitch. The main gear is just forward of the CG. Hope to move the front engine back some with further test flights. It is a darling in the air. Lost the front engine twice and no problem maintaining altitude. Am trying to figure out why it does not build up more groung speed during take-off. Hope to eventually make one engine take-offs. Presently it struggles to taxi on one engine. If it was balsa I would never take-off. This plane will not be hurt if it is forced into the air and doesn't want to fly, which is usually the case. he take-offs require 110% from the pilot. Per your suggestion I will be putting a Zinger pusher on this weekend.