I really do not want to step on peoples toes but if you have never flown a R/C plane with a four blade prop then please do not respond. I have a corsair running a 3 blade prop and it flys just as fast as the two blade. I want a four blade because the p-47 flew with a four blade prop. A lot of people on here have asked the same question but get the run around because everybody wants to put in there opinions from here say. Give me something I can work with. I would rather someone not answer instead of giving me, "you will loose performance and speed compared to a two blade." I am not worried about speed. As of right now I think I am just going to try the 14.5 x 11 on my test stand like rcdude 7 said,and hopefully I get around 9000 rpm.