Description
Diameter
This is the total width of the "circle" at the
blade tips as the propeller spins. Proper diameter for each
propeller model is determined by the propeller's design and
intended application.
Pitch
Pitch is the distance a propeller would travel in one full
revolution, as if traveling through a solid. Each inch of pitch is
equal to approximately **0 RPM, plus or minus *0 RPM. The right
propeller will allow your engine, under a normal to heavy load, to
reach the upper portion of the WOT range specified by its
manufacturer without exceeding it.
AÂ
lower
pitch will have greater acceleration and "pushing
power" but a lower top speed.
AÂ
higher
pitch will provide less acceleration, but a greater
potential for higher top speeds.
Within a particular propeller series, as the diameter increases,
the pitch generally decreases.
Rake
Rake is the angle of the blades in relation to the propeller's
barrel, or center, and is expressed in degrees.
AÂ
high-rake
propeller is best suited for high engine-mount
applications. It reduces ventilation and increases bow lift.
However, too much rake can negatively impact handling and
performance by straining the engine, which will decrease hole
shot.
AÂ
low-rake
propeller causes less strain on the engine,
resulting in a potentially better hole shot and higher wide open
throttle (WOT) operating RPM.
Size
Propeller size is characteristically expressed as its diameter and
pitch, in inches. The diameter is the first number. Pitch is the
second. So a *4" x *7" prop would measure *4" in diameter with *7"
of pitch. This same propeller may be expressed as *4" x *7"x 3,
which would indicate a three-blade design.
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