How do I know what 3 or 4 blade prop to use when going from a single blade prop. Is there a chart or a formula for this. Thanks Bill

I generally drop an inch in diameter when going from a 2 blade to a 3 blade with good results. I also experiment a lot with different prop sizes, which can be expensive with 3 blade'rs. I've never run a 4 blade prop.

Keep the pitch the same and reduce diameter by roughly 10% for 3 blade or 15% for 4 blade.

11x6 gives 10x6 3-blade or 9.5x6 4-blade

20 x10 gives 18 x 10 3-blade or 17 x 10 4-blade

Steve

DK....Keep in mind when going from 2-Blade props to 3,4-blade props(on our models)......there is an effeciency degradation which means if your model is only marginally powered this will make performance worse yet......so either theres plenty of power or you might have to install a bigger powerplant......those 3-4 blade props do look nice though.....Bill....

Get thrust HP and you can calculate it with the software. I have a copy on my website in the links - software section

Just wondering what kind of plane you are thinking of putting a 4 blade prop on? I also looked into getting a multiblade prop for a couple of my warbirds but realized that there was really no way to fit a scale looking 4 blade prop on an r/c aircraft using a regular 2 or 4stroke engine the blade would have to be too short. However there is a new kind of engine available called the RCV engine ,they are basically a 4stroke engine that is geared down to a 2 to 1 ratio allowing one to swing larger props. If you were trying to get a scale 4 blade prop on a plane these are the only way to go. Just a side not, depending on the kind of engine you are using a similar size 3 blade prop may work with your application. I have a super tigre .90 in an old top flight zero, I was dieing to have a 3 blade prop on it, but I didn't want to use a 12 in 3 blade prop. So to make a long story short I used a 14x7 3 blade prop which is a pretty large prop for this engine even if it was a 2 blader. AnywaysI have flown with it for 3 seasons without any problems with the engine. The engine turns a little slower and I run the engine on the rich side which make for quieter and more scale like operations.

my rcv 90 sp spins a 16x10 4 blade rather well on a 60 size thunderbolt and it looks real close to scale to me . great motor!!

jneesy, what manufacture of blade are you using? thanks

zinger 4 blade hub system www.zingerpropellor.com .I wish I could find one that was not wood.

That's propellEr <--- ER not OR

oops