For the 109, I strongly suggest you move the wing forward if you're using a .10 or .15. The wing position on the HOB 109 is at least 3/4 inch rearward from the scale position, and it really doesn't look right. And since it's going to cause balance problems anyway, moving the wing forward is the way to go. Besides, it will give you a longer tail moment, which will probably make it a smoother flier with the big engine. Also, if you can cut yourself a new ply ring for the nose, you can put on a bigger spinner, which will be more scale and help hide some of that big motor.

The reason the wing is placed so far back is that the designer, Fred Reese, made it for a Cox TD .049, which is a very light engine. And he was designing for Ace, which had a line of small spinners for .049 engines. They were too small to be scale on a 109, but I guess the spinners were part of the plan.

It would have been hard to balance without nose weight with the wing in the scale position. Reese wanted to keep it light so it would be a good flier. With the wing moved back, the next problem was pitch stability. He solved that by enlarging the stab. If you moved the wing forward, you could cut the stab down a little bit closer to scale (but I wouldn't go all the way to scale size).

Get a three view of a 109 and you'll see right away what I mean. You can probably get one off the web.

Jim