My man welcome to the butterfly club {more fun than the mile high club) There right that 10 will be working real hard I had a os15 and then fitted the os20 in mine, I like the 20 best but the climb when under power is fantastic. You can trim the thing to fly level and then when the power is increased it climbs. Now if I was to build one more I would add 10 or 15 deg down thrust on the engine thrust so when the power was increased it will fly level. I added 1/4 of an inch of packing to the top of the engine mount to get mine to fly level. Ejam along with Bonified wingnut and myself had a great time building together you need to look at the thread. Yours Paul T