On Sep 9, 2:47*pm, (Richard Casady) wrote:
On Tue, 9 Sep 2008 07:19:30 -0700 (PDT), wrote:
and at a certain RPM they go
through the range of prop pitches.

Those props have a governor that keeps the speed constant, regardless,
within limits, of load or throttle setting. More usual to go through
the range of pitches by varying the RPM with the prop governor. That's
the way everyone I ever knew did it. An airboat doesn't need a
variable pitch prop, as it doesn't climb and dive.

Casady

Richard, I fully understand an airboat doesn't need a vari-pitch prop.
It would be fun to try one to see the difference in the hole shot,
though! When testing controls, it's common to set the RPM's to a
certain setting, more akin to a fast idle, and run the pitch controls
through the range. The prop governor isn't a factor at these low RPM's.