I dont think 4 blade can be used. my neighbor built some like this couple of years back and he couldnt find an engine to pull it. Some people are working on variable pitch 4 blades for rc but nothings out yet that i know of. The pics are great though nice detail
I was wondering the same thing; my hobby shop has a massive Spitfire and P51 but with a 2 blade. The Skyraider is awesome but with all that work I'd be too scared to fly in case it crashed!