"coriolis" wrote in message ...
I find the aerodynamics of fixed pitch props relatively easy to understand -
the angle of attack varies with both forward speed and RPM.

However, something puzzles me about constant speed prop thrust. I realise that
the blades twist to give a different pitch, and therefore when you increase MP
to maintain the same RPM the blades will be at a higher helix angle. However,
won't the angle of attack (calculated by the relative wind) by the same? Isn't
that the idea? If the prop is at the same angle of attack, why is the thrust
higher? Once again, I know the pitch is higher, but isn't the angle of attack
the important thing in generating lift (which is what thrust is) rather than
simply the pitch angle? I've seen texts that say you get a bigger bite, but
that doesn't seem to explain why that matters since lift is predicated on
angle of attack.

Anyone have a good explanation?


http://www.avweb.com/news/pelican/182082-1.html

Best one I've seen.

Matt