Effects of Fixed Vertical Stabilizer Position?

[Dave Hederich]

I'm in the process of replacing a fixed vertical stabilizer on a scratch-built Mini IFOish aircraft with elevon controls. My main questions are how the fore-aft position and size influence the performance of the aircraft. Most of the IFO-type aircraft have the vertical stab mounted far back on the fuse, roughly even with the elevons. One of the locations I'm considering is forward of this, beginning near the center of the fuse rods and ending where the elevons attach to the rear of the mainframe. I believe this will make for a stronger installation (the current vertical stab has broken off).

Would this more forward location have any noticeable influence on flight performance? Is there any rationale for either increasing or reducing the size of the vertical stab based on its fore-aft positioning? Or is this largely irrelevant on a 6 oz., slow-flying model? Any aero advice would be welcome.

[jlk]

The closer to the center of gravity (CG) you move the vertical surface the larger it needs to be. The reverse is also true.

Jordan

[Dave Hederich]

Thanks, Jordan. That does make sense. I think I will stay with a position more toward the rear than the center. It will be somewhat forward from where it is now, so I'll increase the size slightly.