Add wing tip weight.

you can't determine lateral balance on the ground. The model needs to be flying to determine it.

Check all the surface like the elevators and look for aileron warps and such...but I would bet dollars to doughnuts its wing tip weight issue. You will be amazed how a simple 7g mass will affect the situation.

If the right wing is heavy then it will require you to add left aileron trim to hold the wing level in upright flight. But if you roll the model inverted the right wing is now on the left side and gravity will make the model roll left. Your aileron trim is also making the model roll left so the result…Its the heavy wing is the culprit. See gravity is causing you to need the aileron trim not the wings aerodynamic forces. I'm not saying that a warp is not involved. Just that the first thing to stick in there is wing tip weight. What happens is we tune and tune the models until we see all the little warps and twists. The big stuff stands out first then we see all the little warps and twists. The sanding of shapes not the same and those little things. They are subtle. Usually a warp or a twist will be speed dependant not orientation dependent.

If the model was warped and or the rudder trim was off it would act the same upright and inverted. Example if the wing was warped and required aileron trim to hold the wings level.... this would be the same aileron trim for a given speed. You would see a roll tendency as the model flies at different speeds but not upright vs inverted. See aileron trim is only affective for a given speed. But it would not really make the model roll opposite direction unless the speeds are radically different.

If the rudder trim was way off say the model was yawing to the right( and inducing a little roll, that you took out with your aileron trim)...Now roll the model inverted and the aerodynamic forces will still be yawing the model to its right in the same direction relative to the model, So the same corrective aileron trim would be needed. Air flow wise the model doesn't know if it going upright or inverted, knife-edge, straight up of straight down.

Gravity is the constant in this situation. It is always pulling the mass of the model toward the center of the earth. SOOOOO

When you are flying on Knife edge the fuse must make the lift to overcome gravity. When you or going vertical up the engine is making the force to overcome gravity, Straight down the Gravity is pulling the model and no other forces are needed to go straight in this direction.

SO the trick in trimming a model is to get all the forces from the wing, the stab and the engine to balance each other out in such a way that gravity is the only constant. gravity can fool you. If you are tail heavy then gravity will make you add down elevator to raise the tail. A nose heavy model will require up elevator to pick up the nose. This gravity thing can play havoc with your relationships between wing engine and tail. By changing elevator trim all you are really doing is changing the stab incidence. Or to be specific for the experts relative incidence or effective incidence. If you have too much down thrust then a sign is a power off dive. If the stab is carrying un-needed trim to compensate for thrust this will show when you let gravity play the role and not the wings and stabs. If your wing, stab and engine is not properly aligned and flying in equilibrium then you may have a pitch component in vertical downline or upline. For a model to track true all the forces are in equilibrium. This way Aero takes over and the model flies where you tell it by changing the aero. That is all you are doing by moving the controls. Changing the shapes of the lifting surfaces. You are disturbing that equilibrium to make the modle roll, loop, snap or spin.

In your case here you have a wing panel that is heavy, just my opinion. You'll have to add weight to see. Gravity is pulling on the heavier wing and causing the roll. Your aileron trim setting is exaggerating this situation. If you were to add weight to the "lite" panel and fly it you would need to add aileron trim the other way. This would then give you wings level upright or inverted. Same as for CG. If your model was really nose heavy you need to add up elevator trim right? But now roll inverted and the up trim combined with the gravity pulling on the nose is really going to make the model pull toward earth. If you could magically get the CG back far enough you could roll the model inverted and have it stay flying perfectly level with the same elevator trim right? We don't fly that aft of CG because the model doesn't lock in and track. Some guys do...but they won't ever be in the money because the model just don’t track straight and consistent with the CG aft like this. The reason is the model becomes unstable in other axis. It becomes very "unbiased" and will float which ever way the air tells it to. So in the windy conditions the tail heavy model like this will be all over the sky. So we Bias the models based on gravity. We make the model then require some down to hold the nose up when inverted. We can handle this effect and remember when the model is inverted it needs down elevator. The one we can't handle is when the roll trim is affected by gravity. We can't remember the model rolls this way upright but that way inverted. So we need to trim this out.


To test this you need to trim for upright hands off flight all the way across the field. Then roll inverted and hold only elevator...make sure it is only elevator you are holding. Then watch the model for roll. After you add the weight make serval passes upright and make sure it is not rolling at all. Long runs from one end of the field to the other hands off to determine if its right upright. Then roll it on its back and do the same thing holding only down elevator.

I have had very few models that didn't need even a little weight on the tip. My Smaragd Z that I flew for lots and lots of flights carried (2) quarters on a wing tip. Yep about 12g on one tip. By the way this is about 1/3oz. it flew about 4years and well over 3000 flights with those 2 quarters on the wing tip. Weigh the wing panels and they were within just about 3 grams of each other without the ballast on the wing tip....But in the air it could tell the mass was distributed differently. One of my Supreme’s from 2004 didn’t have any wing tip weight but the other one used a single quarter 7g.

The old lateral CG pick-up the nose and the tail and see if a wing drops doesn't work. There is no way for you to truly pick dead center of the fuse. The prop shaft is not it. It has down thrust and right thrust in it. The tail is a similar guess action measurement. So flying it is the only way.

One of my Pinnacles has a single quarter on its tip. And the second and new Pinnacle has about 3-4g a ground down nickel on one tip.

There are a couple of ways to try this out. One is stick a nail in the balsa tip. Not elegant but works. You can tape coins to the wing tip. I use quarters (7g or 1/4oz) for good luck and clear tape. But Nickels (5cents) are the max weight for min investment. Another old timer idea is to use modeling clay. But it needs to be the heavy old time stuff that sticks. The clay allows you remove part of or add to it and it can semi contour to the wing. I had trouble finding clay that fit the bill a few years ago so I gave up on and started using coins. The clay I found was really light weight and didn't stick for spit. I guess it was green peace clay. I think it was guaranteed not to kill a squirrel if he ate it. Or maybe it was would not kill a bunny rabbit it your threw a blob and bounced it off the rabbits head. Then again I was in California looking for clay. Figured it was an artsy enough place....but it was all ecco friendly crap that worked good for making pots, but not suited to this application. So I chose good old US of A AMERICAN money. Coins, easy to replace not expensive, and anywhere you go in the USA you can find a plentiful supply. Lets face it you are adding a $10 roll of quarters to a wingtip you got problems.

For weight if a single coin is too much weight then dremel it. Or get some stick on weights and dremel them. Fishing weights work well too. Once you find the proper weight the model will probably loop track better as well. Once the weight is determined you can stick it into the wing tip and make it hidden. For this I would use small fishing weights and just match the ballast on a gram scale. I have found within a gram is very accurate to determine the amount needed.

Good luck with it.... remember when trimming gravity is your friend and will help you isolate imbalances in your model. Like the wing tip weight issue. Or it can even help you determine thrust issues and wing and stab incidence issues. Basically look at the trim tests. They place the model in tests that includes or eliminates gravity to determine is the aerodynamically the model is flying pure.