I am turning my 68x74 wood prop at 3000 right now in cruise (if it is cool out) with some room left in the throttle, but usually not a lot of room left in the cooling department when going that fast.  However, as I continue to improve on cooling I am finding that I am running up against 3000 rpm.  I don't think I should be running it more than that on a regular basis.

If I can turn my 2-blade 74" prop at 3000k, will I pick up any speed from a 3-blade 74" prop turning at the same speed (through reduced slip)?  If I make the prop shorter can I turn it faster?  I have heard that 900fps prop tip speed is a good upper limit.  Is this a good number to use?  Should I be using that as my cruise tip speed, not max tip speed? 

David;

I’d suggest you direct this info and these questions to Craig Catto, and get the straight scoop.  He knows his props and is very helpful in picking size and pitch for your application.

Al