RE: "Squirrelly" SPAD Gnat
I talked to one of the more experienced guys at our club, and he said the "porpoising" flight characteristics of my plane indicate it is tail heavy. I have a weighted brass prop nut that I can bolt on to shift the CG up w/o modifying anything, so I'll give that a shot and see if it handles better... if so, I'll remount my batt pack to bring the CG up permanently.
This darting up/down or "porpoising" seem to get worse when the nitro tank runs down... further supporting the tail-heavy theory. I'll post again when I get a chance to experiment with moving the CG up.
Correct me if I'm wrong, but reflexing the ailerons up would require more down elevator trim for elevator flight, wouldn't it? The raised ailerons will provide down force behind the CG causing the plane to go up... so some down elevator trim would be required to counter it, right? I think that's why flaperons usually require some up elevator trim/mixing when the ailerons are lowered to act as flaps... down ailerons cause the plane to go down, and up elevator is required to level it off.