On Fri, 19 Oct 2007 07:18:08 -0700, druid wrote:

They do
this apparently because the ANGLE of their blade corresponds to a 6" pitch
(they curve the blade to get the extra thrust).

That is called "cupping" in prop language. Cupping will increase the
effective pitch which is fine if your engine has enough torque to
maintain RPMs. If not you haven't accomplished anything. There is no
free lunch with props.