smap problems
 

Hi,
I have an odd problem. my plane flies great good flight tail slides roll inverted, But when I give it the slightest but of down elevator inverted to climb or do an outside loop the plane snaps out. It will also snap out of knife edge. not straight knofe edge but when I start to turn in knofe edge it does not like the elevator.

my CG balance is not the problem I have gone 1 inch before and 1 inch after and it does not improve .

I was wondering if it seemed to be incidence or ailerons high or low let me know if you have ever has that problem

smap problems
 

The condition you are describing might be the result of wash out. Wash out is a slight twisting of the wing to lower the angle of attack at the wing tips. This is done so the center of the wing stalls before the tips resulting in a nice friendly nose first stall. When inverted, the effect is just the opposite forcing the wing tips to stall first, and unless they stall absolutely simultaneously you will get a snap roll. What plane are you flying? Many sport planes and early pattern planes use washout.

Inverted Tip Stall.
 

Washout is a likely suspect as discussed in the above post. Other possible causes may be related to a lot of taper in the planform and an airfoil with a sharp inverted stall. Airfoils with meanline cambers (as opposed to symmetrical airfoils) need to be flown a lot faster when inverted than when upright inorder to avoid stall.