Thanks for the links. I have actually been to Zinger's site and saw that very page. I have read that if you use a 3-blade prop over a 2-blade that you need to reduce the diameter by an inch. The .25's use a 9x6 typically, so that would imply a 3-blade 8x6. I wonder if the 10x4 that zinger makes would be usable. By thrust alone, the 10x4 makes less thrust than a 9x6. What do you think?