I have a flapped ship that is very happy both upright and inverted but it wants to fly at 12'. Now I've moved the CG forward and it helps but this requires harder control input and doesn't grove as well. The linkage is all tight. I was wondering about adding in some elevator slop. How much? Instead of drilling out the elevator horn is there a way to get the same effect by changing the stab geometry?
I don't see why you needed to move the CG forward to get it to fly lower. Is this just upright or inverted, or both? If it's one or the other, it's probably a handle, incidence, or flap/elevator neutral problem, if it's both, it's probably a combination of these issues.
The answer to the question is that you can sort of get the same effect by making the stab smaller than the elevator, but that will soften your response around neutral and not really entirely get the effect. Slop doesn't really do what traditional wisdom says, anyway - back in the good old days, with bent wire pushrods and bushings, you had either slop, or binding. If it binds up it is very likely to hunt or not groove well. If you get it loose enough to not bind up, it has some slop. Now, we have had plenty of models with ball links everywhere that have no slop, but don't bind. AND, you can adjust the flap/elevator neutral. Suddenly, despite air being roughly the same as it was in 1960, you no longer need slop!
Brett