ORIGINAL: haikt
i did test fly it without the motor and it glides ok, but on the lunch it will loop up like crazy and its uncntrolable, a have been flying for 5 years so i think it is not all my skills fault but could be,
12.5% FPRM LE IS NOT ENOGHT, HOW FAR THAN.
tHANK YOU
Don't get testy. We're trying to help you.
The first suggestions you got for the CG is to start at 10% aft (back from the front). To find this location, you'll have to find your mean airfoil chord (MAC). If your wing is swept forward or aft, the MAC is swept as well requiring you to find the correct measurement for the CG location.
OK,
If it glides stable on its own WITHOUT ANY INPUT FROM YOU, but won't fly stable with the engine running (at least I think that's what you're trying to say it is doing), then the engine is not set at 0°. -> Set the enine at exactly 0° (no left/right, no up/down) and try again.
What airfoil did you use for this design?
D