High speed propeller optimization under 8 feet diameter

[jakksincorpse]

at what diameter, pitch, and blade number would be the best combination for a high speed propeller? i'd like the diameter to be under 8 foot in diameter.

 

[Cyphear]

I have heard that if they start breaking the speed of sound then you lose power. I'd copy a prop design that already exists.

There's lots of info about this. Have you read any of this?

http://www.google.com/search?q=propeller+design