I picked up a couple of the World Models Skyraider Mach I (high wing version, more wing than the low wing) for use as club fun-fly planes. I was originally thinking of Irvine 53 for them, but in looking at the wing area, they seem more like a 60 size plane (remember club fun-fly not trainer purposes). I used to have an Easy sport 40 I built, that I put an Os 61 on, and that was a great combo, couldn't imagine having a 40 on it.

So the question is, should I stick with the original Irvine 53 idea, or bump up in size to a 61 or 72 two stroke size engine? I don't want to rip them apart, but, hey, if they hover at 1/2 throttle, thats ok too!

I would stick to the 50 size rather than the 60 as they fly well enough on a 40 2 stroke. I would imagine that a 50 would give it almost unlimited vertical with a 12x4 or 13x4 prop! Crank the control rates up and you will have one fun flying plane.

Thanks for the input bigsport. I want it to be a deamon, but don't want it to rip apart...on the first flight ....

Seems to me that you are set on two strokes.....if not, the ASP .52 four stroke is awesome on this plane. Try a Saito FA 70 also..you won't regret it.
This plane is an awesome trainer. Does anything you ask of it and more.

Cheers.