Billy this Yaw can happen when you have issues with your right thrust. ..there could be other things I'll discuss down below. Assuming the flying surfaces are right on....the thrust offset alone can cause this issue.

Think about it....right thrust is there to keep the vertical lines good, Yet we tend to trim the model in yaw or rudder while upright....I do it flying straight away from myself.

Now roll the model inverted and your right thrust becomes left thrust, and the rudder trim you may be carrying to fly upright and true in yaw is not working against what ever else you have going on.

Mismatched elevators can cause this too. You trim the rudder thinking it needs some trim but reality is the elevators being off a touch will tend to make yaw rather than roll. Same with stab adjustments...if a stab is off compared to the other side this will do the same. Usually stabs and elevator make yaw problems not roll problems. And they have to be off a bit to cause roll issues or loop tracking issues in roll. But off by just a little can cause issues with yaw. And can interact with thrust settings too.

I would look to a change in the thrust line or look for the stab and elevator alignment..


OR.....Something else going on like a bent fuse. If the two fuse sides are not identical this can happen. I had a model manufacture red in Argentina, the fuse was straight but the fuse sides were not the same. When you shot a laser down the fuse centerline it was dead on....But shooting a laser down the surface of the side or using a straight edge it revealed that the fuse halves were not mirror images. And in fact one of the fuse sides had a bow in it.

This meant it had funny yaw conditions upright and inverted, it would even yaw differently on 45's upright or inverted compared to verticals and horizontal lines.

This all made for a very speed sensitive model.

A fin that is not perpendicular to the stab and wing can have similar effects too. Or a stab that is not parallel to the wing.

I'm not sure what you are flying but....it could be something simple.....like thrust or stab-elevator align or it could be molded in and you are stuck with it. Then the trick is to mess up something else like the stab-elevator alignment to make it screw up the other way and cancel the problem out. I did this on my bent fuse model. It worked pretty well but would change with airspeed. So I fixed it for 1/2 throttle then go busy in the mix department for idle and full power settings. It is possible to fix it with a combo of mechanical changes and electronic mixing....but it can get time consuming and complicated.

The best thing for the stabs is a dead flat table and some height gauge work to make sure the stab is at the incidence on both sides and the elevators...are dead on...Also eye ball the elevators. If they were sanded or molded and are not mirror images its the same as them having the trailing off....in these cases you have to shoot the middle. Its usually not going to be 1000% perfect but you can get really close to not feel the problem...with a 1/2 clevis turn or the likes.


Troy Newman