Hey buckijim. Doesn't it say in your instruction manual whether to balance the plane with an empty or full fuel tank? (But I've never heard of a manual that instructed one to balance with a full tank.)

Most of the time the plane is balanced with the fuel tank empty. That way, the plane will start out nose heavy, but when the tank is empty it will be at its most "tail-heavy" balance point. If the designer/builder/instruction manual writer did his job correctly, the empty vs. full fuel tank situation will have been accounted for in their balance point testing.

What we usually do at GP is make certain the plane will be able to flair on landing on low rate elevator with a full fuel tank, but not unexpectedly tip stall or snaproll whenever full elevator is pulled on high rates with a near empty fuel tank. This way, the modeler should never get into trouble.