Knowing the HP, RPM and Speed you can calculate an correct Propeller the
first time.
You can do that with pen and paper, hand-calculator or why not a computer.
The Computer make it possible to calculate it faster and more exact, easy to
change a parameter and see the result and get warnings when it start to get
unsafe, all in a milli sec.


lets see ive got 15hp, 3400rpm and 25mph...can you help me out with
the calculations? thank you