>>10964723Don't use a washer aroind the hole, offset it to the side, otherwise your plane will always have its tail towards the hole and its nise away from it, so you'd always be looking straight at the back of the plane rather than the plane being at the edge of vision. I also wouldn't do a nose-tail alignment, because that way your string wil always be along that same axis, and if you want to see part of the canopy of the plane you will always see the string.
Equally spicy pics to show what I mean. 1/3 your proposed method, nose to tail centered on viewing hole.