Definetely put the .40 sized engine in it. A smaller engine will not do what you want with this model, especially if there is wind. It is a nice building product, easy and gets you to understand what all the jargon is for later more experience required kits. It's my first and only plane at the moment and I engine flying it alot. I haven't been flying much, a bit last year...more so this year. I am still learning and enjoying. FYI I built this kit when I was 21...I was 31 (last year) when I flew it the first time. Couldn't find anyone to fly with or a place to fly it until then. Everything (but the engine) worked without a hitch and continues to do so to date. (knocks on wood)

S