Dick, Did you find that the cg shifted aft with a full tank? Mine was balanced at 4" with empty tank, got airborn and plane was tail heavy. Checked on ground with full tank, and cg was at 4 1/2" I had to add ANOTHER pound of lead to get nose down a tad. Plane now weighs in at 9 pounds even (empty) I'm gonna try flying with half a tank and see what difference it makes in balance. There is over half the tank aft of 4" CG point... Make a difference you think?