hmm so i found this little model aiplane prop calculator utility...
http://www.gylesaero.com/freeware/propcalc.shtml

i plug in 3400 rpm and 0mph airspeed (static) and if i want ~100lbs of
thrust w/a 2blade it says i need an 8" pitch 50" diameter prop... i
think thats doable but many questions remain...

how do i select a propeller airfoil, aspect ratio?
does an 8" pitch seem reasonable for my application? thats 3.8degrees
at 0.75r if this little caculator is correct
so is pitch usually measures at 3/4 the radius of the prop?
how then do i determine twist from tip to hub?
Shold i just use constant pitch with no twist for simplicity?
how broad should the blade be?

aaaahh...


(sebastian) wrote in message . com...
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