PoF LO5 p1
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Transcript of PoF LO5 p1
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Uncontrolled copy not subject to amendment
Principles of Flight
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Principles of Flight
Learning Outcome 5:
Be able to apply the principles of flight and control
to rotary wing aircraft
Part 1
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Questions
Name the Forces Acting on a Glider in Normal Flight.
a. Force, Weight and Lift.
b. Drag, Weight and Thrust.
c. Drag, Weight and Lift.
d. Drag, Thrust and Lift.
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Questions
How does a Glider Pilot Increase the Airspeed?
a. Operate the Airbrakes.
b. Lower the Nose by pushing the Stick Forward.
c. Raise the Nose by pulling the Stick Back.
d. Lower the Nose by pulling the Stick Back.
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Questions
A Viking Glider descends from 1640 ft (0.5 km).
How far over the ground does it Travel (in still air)?
a. 17.5 kms.
b. 35 kms.
c. 70 kms.
d. 8.75 kms.
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Questions
When flying into a Headwind, the distance covered
over the ground will:
a. Be the same.
b. Decrease.
c. Increase.
d. No change.
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PropellersObjectives:
1. Define Blade Angle and Blade Angle of Attack.2. Show with the aid of a diagram the Aerodynamic
Forces acting on a Propeller Blade in flight.
3. Explain Aerodynamic and Centrifugal Twisting
Moments acting on a propeller.4. Explain the effect of changing forward speed on:
a. A Fixed Pitch propeller.
b. A Variable Pitch propeller.
(and thus the advantages of a variable pitch propeller).
5. Explain the factors causing swings on take-off for:
a. A Nose-Wheel aircraft.
b. A Tail- Wheel aircraft.
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MOD
Propellers
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Propellers
(Terminology)
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Propellers
(Terminology)
Airflow due
to RotationalVelocity
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Propellers
(Terminology)
Induced Flow
Airflow due
to RotationalVelocity
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Propellers
(Terminology)
Induced Flow
Airflow due
to RotationalVelocity
RelativeAirflow
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Propellers
(Terminology)
Induced Flow
Airflow due
to RotationalVelocity
RelativeAirflow
ChordLine
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Propellers
(Terminology)
Induced Flow
Airflow due
to RotationalVelocity
RelativeAirflow
= AofA
ChordLine
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Propellers
(Terminology)
Induced Flow
Airflow due
to RotationalVelocity
RelativeAirflow
= AofA
= Blade Angle
Chord
Line
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Total Inflow
Propellers Blade Twist
Approx 4o
Angle of Attack
Rotational
Velocity
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Effect of Airspeed
Induced Flow
Airflow due
to RotationalVelocity
At Zero
Airspeed
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Induced Flow
Airflow due
to RotationalVelocity
(Same)
At a Forward
Airspeed
=Total InflowTAS +
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Effect of Airspeed
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Effect of Airspeed
Induced Flow
Airflow due
to RotationalVelocity
(Same)
=Total InflowTAS +
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At a Forward
Airspeed
Need larger for same
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Effect of Airspeed
_
_
_
_
100%
75%
50%
25%
True Airspeed
Fine
CoarsePropeller
Efficiency
at Max Power
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Pitch of
Propeller Blade
_
_
_
_
100%
75%
50%
25%
True Airspeed
Fine
Coarse
Variable Pitch
Propeller
Efficiency
at Max Power
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Why a different Number of Blades?
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Aerodynamic
Forces
Total Inflow
Airflow due
to RotationalVelocity
RAF
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Aerodynamic
Forces
Total Inflow
Airflow due
to RotationalVelocity
RAF
Total
Reaction
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Aerodynamic
Forces
Total Inflow
Airflow due
to RotationalVelocity
RAF
Lift
Drag
Total
Reaction
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Aerodynamic
Forces
Total Inflow
Airflow due
to RotationalVelocity
RAF
Total
Reaction
Thrust
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Aerodynamic
Forces
Total Inflow
Airflow due
to RotationalVelocity
RAF
Total
Reaction
Thrust
Prop
Rotational
Drag
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Aerodynamic Forces
(Effect of High Speed)
TAS+Induced Flow
Airflow due
to RotationalVelocity
RAF
Total
Reaction
Thrust
Slow
Speed
Fixed
Pitch
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TAS+Induced Flow
Airflow due
to RotationalVelocity
RAF
Total
Reaction
Thrust
High
Speed
Fixed
Pitch
Aerodynamic Forces
(Effect of High Speed)
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TAS+Induced Flow
Airflow due
to RotationalVelocity
RAF
Total
Reaction
Thrust
High
Speed
Fixed
Pitch
Aerodynamic Forces
(Effect of High Speed)
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TAS+Induced Flow
Airflow due
to RotationalVelocity
RAF
Total
Reaction
Thrust
High
Speed
Fixed
Pitch
Aerodynamic Forces
(Effect of High Speed)
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TAS+Induced Flow
Airflow due
to RotationalVelocity
RAF
NB: Rotational Drag
reduced, RPM ?
Thrust
High
Speed
Fixed
Pitch
Aerodynamic Forces
(Effect of High Speed)
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TAS+Induced Flow
Airflow due
to RotationalVelocity
RAF
NB: Rotational Drag
reduced, RPM increases.
Dont exceed limits.
Thrust
High
Speed
Fixed
Pitch
Aerodynamic Forces
(Effect of High Speed)
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TAS+Induced Flow
Airflow due
to RotationalVelocity
RAF
Total
Reaction
Thrust
Slow
Speed
Variable
Pitch
Aerodynamic Forces
(Effect of High Speed)
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Faster TAS+Induced Flow
Airflow due
to RotationalVelocity
RAF
Total
Reaction
Thrust(eventually
reduces) High
Speed
Variable
Pitch(same or possibly greater)
Aerodynamic Forces
(Effect of High Speed)
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Windmilling
Propeller
Negative
TAS
Airflowdue to
Rotational
Velocity
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Windmilling
Propeller
Negative
TAS
Airflowdue to
Rotational
Velocity
TR
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Negative
TAS
Airflowdue to
Rotational
Velocity
TR
Negative Thrust
(Drag)
Windmilling
Propeller
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Negative
TAS
Airflowdue to
Rotational
Velocity
TR
Negative Thrust
(Drag)
Negative
Rotational
Drag (Driving
The Propeller)
Windmilling
Propeller
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Negative
TAS
Airflowdue to
Rotational
Velocity
TR
Negative Thrust
(Drag)
Negative
Rotational
Drag (Driving
The Propeller)
This may cause
further damage,
even Fire.
Windmilling
Propeller
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Note that in Firefly/Tutor prop goes to Fine Pitch
if engine rotating, Coarse Pitch if engine seized
Feathered
Propeller
Although twisted, in aggregate,blade at Zero Lift .Therefore drag at minimum.
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Take-Off Swings
All Aircraft:Torque Reaction means greater rolling
resistance on one wheel
Helical slipstream acts more on oneside of the fin than the other
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Take-Off Swings
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Take-Off Swings
Tail wheel aircraft only:
Asymmetric blade effect
Gyroscopic effect
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Take-Off Swings
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Take-Off Swings
Affect all aircraft on rotate?
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Take-Off Swings
All Aircraft:
Dont forget crosswind effect!
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Centrifugal Twisting Moment
Tries to fine blade off
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Aerodynamic Twisting Moment
Relative Airflow
Total Reaction
Tries to coarsen blade up
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Aerodynamic Twisting Moment
Windmilling
Relative Airflow
Total Reaction
Tries to fine blade off
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ANY QUESTIONS?
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PropellersObjectives:
1. Define Blade Angle and Blade Angle of Attack.
2. Show with the aid of a diagram the Aerodynamic
Forces acting on a Propeller Blade in flight.
3. Explain Aerodynamic and Centrifugal Twisting
Moments acting on a propeller.4. Explain the effect of changing forward speed on:
a. A Fixed Pitch propeller.
b. A Variable Pitch propeller.
(and thus the advantages of a variable pitch propeller).5. Explain the factors causing swings on take-off for:
a. A Nose-Wheel aircraft.
b. A Tail- Wheel aircraft.
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Questions
Blade Angle of Attack is between?
a. The Chord and Relative Airflow.
b. The Rotational Velocity and the Relative Airflow.
c. The Total Reaction and the Chord.
d. Lift and Drag.
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Questions
Increasing speed with a fixed pitch propeller will?
a. Be more efficient.
b. Reduce efficiency.
c. Make no difference.
d. Increase the Engine speed.
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Questions
The Forces trying to alter the Propeller Blade
Angle of Attack are?
a.ATM and CTM.
b. CDM and ATM.
c. CTM and REV.
d. AOA and ATM.
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Questions
The Resultant Forces that a Propeller produce are?
a. Lift and Thrust.
b. Thrust and Propeller Rotational Drag.
c. Drag and Total Reaction.
d. Drag and Thrust.
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