This chart is from Martin Hollmann book Prop and
Duct Design.
Advance ratio is another way of saying pitch sort
of.
You can read the x axis as aircraft speed sort of.
Notice as the pitch is reduced the max efficiency
speed is lowered.
Notice also if a fixed pitch prop is chosen for
cruise the efficiency
is very low at low speeds.

Paul Lamar

Vance Jaqua wrote:

Advance ratio is propeller talk for aircraft speed
versus rpm. Maximum "propeller efficiency" (really
propulsive efficiency")  is bounded by the laws of
physics to a curve starting at zero speed as a
function of disc loading Those so called peaks of
efficiency are
where the specific prop in question starts over
running it's pitch on its way to becoming a windmill.
Those types of curves, although generally taken from
data, are usually of little use for you in sizing a
prop (or understanding a prop for that matter) - Vance

Enlighten us further oh great one.
Supply us with the bounds of the laws of physics in a way mere
mortals can understand.

What ever are you driving at Vance?

Paul Lamar
 
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