ORIGINAL: Fastsky
Interesting results on your end. It might also be about how close to level you like the plane to balance. I like to see the nose come down about 2" from level. I tried a neautral cg where the nose stayed perfectly level and I didn't like the results when the plane stalled. Instead of nosing down a bit and starting to fly again the plane simply started dropping straight down like an elevator. The plane stayed level because of the lateral balance but lost altitude like crazy! Come to think of it my Super Decathlon did require some tail weight, forgot about that one!! Cheers!
"I tried a neautral cg where the nose stayed perfectly level"
Now is that some form of "new aerodynamics" like the once spouted "new math"?
That point on the Lateral Axis of the aircraft where the nose and tail hang level
IS THE CENTER-OF-GRAVITY (CG)
If the nose hangs down, then the actual CG is some distance forward of the point of support.
The CG is established by the equality of weight on either side of the CG. Adding and/or subtracting weight moves the CG and thus the lateral axis.
Stability and instability are functions of the CG and the airfoil's Aerodynamic Center which is -- in subsonic aircraft -- about 25% of the chord. CGs aft of that point increase in unstable situations. CGs forward of that point increase stability.
If you are hanging your model at the 30% of the Mean Aerodynamic Chord and it hangs level, it will fly but less stable than if at 25% of MAC. CGs in most sport models aft of 33% MAC will usually not be a pleasure to fly, and as your "neutral CG" model will easily enter into flat spins.
What some designer writes on plans has no effect on the model if you build it with substantial weight differential distribution. The CG is a balance point. If too far aft add weight forward, or vice versa. Locate that balance point (CG) at 25-28% of the MAC. Try that. If you want to be more lively, then gradually go aft a percent or two at a time.
BTW the Avistar is a good trainer, especially with a reliable .40.