UPnet,

Glad to help. I had a Shoestring for 4 seasons with an OS 61 in it. The plane flew so well I bought a second one which is still in the box. As for engines, I had to add 1 ounce of lead to the tail to get mine to balance. If you put to big of engine in it you will need more weight to the tail to balance. One question you need to ask your self is how do I intend to fly it. With a 61 or 75 it will be great sport flying plane. I would only use a 91 or larger if you intend to race it.

Dave