I'm scratch-building a Pitts Special, from Nick Ziroli plans from 1967. The plans don't provide finished weight, but the sketchy instructions that came with them suggest a .45-.60 size two-stroke. (Specifically, those instructions say the prototype carried a .46, and that was "minimally acceptable.") And, remember this was all said in 1967.

The longer wing-span is 53", the shorter is 44", and the fuse is 45" long. Similar sized ARFs on the market generally recommend .60 sized two-strokes or .90 sized four strokes. The airplane is balsa and ply built-up, mostly sheeted with 1/8" balsa, and I'll cover it with some brand of film.

My objective for performance is primarily reliabilty. I'm not looking for a screamer, but I don't want to regret under-powering it. Also, I take some pride in trying to be economical - I'd rather spend less money than more, although I don't want to be foolishly cheap about it. I don't have a strong preference between a 2-stroke or a 4-stroke.

I'm considering the Tower .75 two-stroke. What do you guys think?