4 blade props

[Johnson_Jack]

G'Day all,

On the subject of 4 blade props, when looking at rpm etc, how does a 4 blader compare with a 3 blade?

For example

say you get 6200rpm on a 3 blade 15" pitch prop, changing this to a 16" pitch will bring your rpm down approx 200 to 6000(figures just for the excercise)

What I'd like to know is what effect will a 4 blade have here, say you just went to a 4 blade 15" would it have any effect?

And if on same set up you went 4 blade 16" will effect be same 200, or greater or less?

I'm figuring it must have a greater effect, but unsure, any prop experts care to enlighten me?

Cheers

[Spaniard_King]

4 Blades are #very efficient props, they take a lot of HP to drive them at high RPM's from experience you loose about 300rpm for the same pitch in a 4 blade

cheers

Garry