ORIGINAL: Jim Thomerson
I think Da Rock's explaination of pitch distribution along the blade is quite optomistic. The usual best is to make a helical pitch prop, where the pitch at any station gives the same forward "screw motion" as any other. And yes people put wash in or wash out to make things better, they hope.
hope in one hand and **** in the other
Having blown way too much cash and also doing prop evaluations for a few companies- The entire prop market is pretty much smoke n mirrors
Except
The carbon fibre props keep their shape at high power loads and therefor are more accurate and stable which allows the motor/engine to rev to full potential.
The APC's really are in a class by themselves when it comes to matching a particiular job. and a good price.
They make testing sooo much easier.
Put aside personal feelings about wide blade vs narrow blade - most of these old observations are invalid. It is all about load and the speed where the max possible motor/engine POWER is desired
fo example:
To go fast I prop up to where max watts hit at about the speed I am shooting for
then -ready for this?
I hope I guessed right.
Then I change props and try again
Anyone who thinks they can accurately compute the speed and load is kidding themselves
They may (read that MAYBE), get in the right ballpark but that's all.
You want to go fast ?
here is the secret formula -don't tell the aerodynamicists , some may feel left out
Get as much power as possible in the smallest lightest model possible
then shape it as well as you can to make it slippery
All in that order.