Thanks again for your help. Your post along with this article..
http://www.masportaviator.com/ah.asp...&ID=72&index=0

has helped me out a lot. I think I know where to head next. I just have one more quick question about number of blades. We've been using a 4-bladed prop, but diameter and pitch choices are limited. I remember from one of my classes that more blades can provide more thrust, but they also cause more interference with each other, making the efficiency worse. Does the number of blades affect the performance significantly, or is it merely for looks/show.