AMT 126 AC PROP Flashcards
The forward pull of the propeller
which tends to bend the blades
forward (bending force).
Thrust
are shaped much like a
wing of an aircraft, using the rotation power of
an engine rotates the propeller blades produce
lift (this lift is referred to as thrust) which
moves the aircraft forward.
Propeller Blades
Each propeller blade is a rotating airfoil which
produces ____ and _____
lift and drag force
Since the length of the propeller assembly along the
engine crankshaft is short in comparison to its diameter,
and since the blades are secured to the hub so they lie in
the same plane perpendicular to the running axis, the
dynamic unbalance resulting from improper mass
distribution is negligible.
Aircraft Propeller Balancing
also produces drag that tends to
hold the aircraft back and slow it down, and
the amount of drag it makes depends on the
angle of the blades.
Propeller
_______ convert engine
horsepower into thrust by
accelerating air and creating a low-pressure differential in front of the
propeller. Since air naturally moves
from high to low-pressure, when
your prop is spinning, you’re being
pulled forward.
Propellers
comes from Sir Isaac Newton. Newton’s
third law states that “for every action, there is an
equal and opposite reaction”
Torque
A spinning propeller is essentially a gyroscope,
which is a spinning disc. That means it has the two
properties of a gyroscope: rigidity in space and
precession.
Gyroscopic Precession
are present in a propeller since it is also an
airfoil.
lift and drag force
results when the CG of similar
propeller elements, such as blades or counterweights, does
not follow in the same plane of rotation.
Dynamic Imbalance
results when the thrust (or pull) of the blades
is unequal. This type of unbalance can be largely
eliminated by checking blade contour and blade angle
setting.
aerodynamic unbalance
It is the force created by the whirling
motion of the propeller results in the
tendency of the blades out of the hub.
Centrifugal Force
______ and _____ are also seen on propellers because they
are generally rotating airfoils.
Induced Drag and Parasite Drag
Most western aircraft have engines that rotate
clockwise when viewed from the cockpit. That’s
where _____ comes into play.
torque
, your downward sweeping
blade is at a much higher angle-of-attack than your
upward sweeping blade. And with a higher AOA, the
downward sweeping blade creates much more thrust
(or lift), making your airplane want to yaw to the left.
P-Factor
This force is effectively pulling the
propeller away from the aircraft.
Centrifugal Force
is a source of vibration in an aircraft.
Unbalance Propeller
The propeller, with its rapidly spinning lifting force, it
creates the thrust that makes airplanes move, it also
creates four unwanted effects that pilots must learn to
recognize and respond to.
Left Turning Tendencies
Propeller unbalance, which is a source of vibration in an
aircraft, may be either static or dynamic.
Aircraft Propeller Balancing
in an aircraft are caused by the rotating
propeller.
Left Turning Tendencies
4 Left Turning Tendencies:
Torque effect, P-factor, Gyroscopic Precession, Spiraling Slipstream
Tendency of the propeller blade to
rotate in their sockets towards low
blade angle (flattening tendency).
Aerodynamic Twisting Force
occurs when the center of
gravity (CG) of the propeller does not coincide with the
axis of rotation.
Propeller Static Imbalance
Precession happens when you apply force to a
spinning disc. When a force is applied to one point
of the disc, and the effect of that force (the
resultant force) is felt 90 degrees in the direction of
rotation of the disc.
Gyroscopic Precession
pulls away the propeller from the aircraft.
Centrifugal Force
twists the propeller to a low blade
angle.
Aerodynamic Twisting Force
Since the propeller is spinning clockwise, that force
is felt 90 degrees to the right. That forward-moving
force, on the right side of the propeller, creates a
yawing motion to the left.
Gyroscopic Precession
which is also called “asymmetric propeller
loading”, happens when the downward moving
propeller blade takes a bigger “bite” of air than the
upward moving blade.
P-Factor
force tends to bend the propeller forward.
thrust
Your plane is flying at a high angle-of-attack (takeoff
and slow-flight are good examples).
P-Factor
The high-speed rotation of an
aircraft propeller gives a corkscrew
or spiraling rotation to the
slipstream. At high propeller speeds
and low forward speed (takeoffs,
approaches, power-on stalls), this
spiraling rotation is very compact
and exerts a strong sideward force
on the aircraft’s vertical tail
surface
Spiraling Slipstream
As you throttle up your engine for takeoff, the
right-turning direction of your engine and propeller
forces the left side of your airplane down toward
the runway. When the left side of the airplane is
forced down onto the runway, the left tire has more
friction with the ground than the right tire, making
your aircraft want to turn left.
Torque
You’re taking off in a tailwheel airplane.
P-Factor
