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Propellers
How Propeller Works & Functions Of Propeller
engineeringinsider
A propeller works in a similar way that a screw works.
The blades of the propeller are an aerofoil, which generates an
aerodynamic force as they spin, the same as any other aerofoil that is moving
through the air.
The blades of a propeller are slightly angled. As the blade
rotates, air accelerates over the front surface, causing a reduced static
pressure ahead of the blade.
This results in a forward thrust, which pulls the aircraft
along.
When the aircraft is stationary, the spinning propeller blades
cause purely rotational velocity.
As the aircraft moves forward in flight, the propeller produces
both rotational and forward velocity.
The combined vector of these forces is called the pitch, the
angle of advance.
As a result of this combined rotational and forward velocity,
each propeller blade section follows a ‘corkscrew’ path through the air.
Different points along the blade will have an optimal angle to
the relative airflow to operate efficiently at a given airspeed.
Propellers are designed to have the most efficient angle of
attack along the entire length.
To achieve this, blades are designed with a twist, which reduces
the blade angle from the centre to the tip.
Fixed-pitch propellers have only one forward velocity (airspeed)
for a given rpm at which they will operate efficiently.
Some propellers are designed with the ability for pilots to adjust
the pitch in flight, allowing the propeller to operate most efficiently over a
wider range of airspeeds.
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