I rib-stiched the control surfaces. I used 2 inch spacing on the ailerons and 1.5 inches on the flaps, per the Poly-Fiber manual ( the ailerons are out of the propwash). I found I liked the straight needle for passing the lacing material between the upper and lower surface and only used the curved needle to pass the lace to the next stich-site. Also, I found an old Poly-Tak cap was useful for pushing the needle forward, when it tended to drag.
