LO5: Simulation of transit signal priority strategies for brt operations
Po f lo5 p1
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Principles of Flight
Principles of Flight
Learning Outcome 5:
Be able to apply the principles of flight and control to rotary wing aircraft
Part 1
Questions
Name the Forces Acting on a Glider in Normal Flight.
a. Force, Weight and Lift.
b. Drag, Weight and Thrust.
d. Drag, Weight and Lift.
e. Drag, Thrust and Lift.
Questions
How does a Glider Pilot Increase the Airspeed?
a. Operate the Airbrakes.
b. Lower the Nose by pushing the Stick Forward.
d. Raise the Nose by pulling the Stick Back.
e. Lower the Nose by pulling the Stick Back.
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.
e. 70 kms.
f. 8.75 kms.
Questions
When flying into a Headwind, the distance covered
over the ground will:
a. Be the same.
b. Decrease.
e. Increase.
f. No change.
PropellersObjectives:
2. Define Blade Angle and Blade Angle of Attack.
3. Show with the aid of a diagram the Aerodynamic
Forces acting on a Propeller Blade in flight.
5. 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.
MOD
Propellers
Propellers(Terminology)
Propellers(Terminology)
Airflow dueto RotationalVelocity
Propellers(Terminology)
Induced Flow
Airflow dueto RotationalVelocity
Propellers(Terminology)
Induced Flow
Airflow dueto RotationalVelocity
Relative Airflow
Propellers(Terminology)
Induced Flow
Airflow dueto RotationalVelocity
Relative Airflow
ChordLine
Propellers(Terminology)
Induced Flow
Airflow dueto RotationalVelocity
Relative Airflowα
α= AofA
ChordLine
Propellers(Terminology)
Induced Flow
Airflow dueto RotationalVelocity
Relative Airflow
β
α
α= AofA
β= Blade Angle
ChordLine
Total Inflow
Propellers Blade Twist
Approx 4o
Angle of Attack
Rotational
Velocity
Effect of Airspeed
Induced Flow
Airflow dueto RotationalVelocity
β
α
At Zero Airspeed
Induced Flow
Airflow dueto RotationalVelocity (Same)
βAt a Forward Airspeed
α
= Total InflowTAS +
-α
Effect of Airspeed
Effect of Airspeed
Induced Flow
Airflow dueto RotationalVelocity (Same)
β
α
= Total InflowTAS +
-α
At a Forward AirspeedNeed larger β for same α
Effect of Airspeed
_
_
_
_
100%
75%
50%
25%
True Airspeed
Fine
CoarsePropellerEfficiencyat Max Power
Pitch ofPropeller Blade
_
_
_
_
100%
75%
50%
25%
True Airspeed
Fine
Coarse
Variable Pitch
PropellerEfficiencyat Max Power
Why a different Number of Blades?
Aerodynamic Forces
Total Inflow
Airflow dueto RotationalVelocity
RAFα
Aerodynamic Forces
Total Inflow
Airflow dueto RotationalVelocity
RAF
TotalReaction
α
Aerodynamic Forces
Total Inflow
Airflow dueto RotationalVelocity
RAF
Lift
Drag
TotalReaction
α
Aerodynamic Forces
Total Inflow
Airflow dueto RotationalVelocity
RAF
TotalReaction
α
Thrust
Aerodynamic Forces
Total Inflow
Airflow dueto RotationalVelocity
RAF
TotalReaction
α
Thrust
PropRotationalDrag
Aerodynamic Forces(Effect of High Speed)
TAS+Induced Flow
Airflow dueto RotationalVelocity
RAF
TotalReaction
α
Thrust
Slow SpeedFixedPitch
TAS+Induced Flow
Airflow dueto RotationalVelocity
RAF
TotalReaction
α
Thrust
High SpeedFixedPitch
Aerodynamic Forces(Effect of High Speed)
TAS+Induced Flow
Airflow dueto RotationalVelocity
RAF
TotalReaction
α
Thrust
High SpeedFixedPitch
Aerodynamic Forces(Effect of High Speed)
TAS+Induced Flow
Airflow dueto RotationalVelocity
RAF
TotalReaction
α
Thrust
High SpeedFixedPitch
Aerodynamic Forces(Effect of High Speed)
TAS+Induced Flow
Airflow dueto RotationalVelocity
RAF
NB: Rotational Dragreduced, RPM ?
α
Thrust
High SpeedFixedPitch
Aerodynamic Forces(Effect of High Speed)
TAS+Induced Flow
Airflow dueto RotationalVelocity
RAF
NB: Rotational Dragreduced, RPM increases.Don’t exceed limits.
α
Thrust
High SpeedFixedPitch
Aerodynamic Forces(Effect of High Speed)
TAS+Induced Flow
Airflow dueto RotationalVelocity
RAF
TotalReaction
α
Thrust
Slow SpeedVariablePitch
Aerodynamic Forces(Effect of High Speed)
Faster TAS+Induced Flow
Airflow dueto RotationalVelocity
RAF
TotalReaction
α
Thrust (eventuallyreduces) High
SpeedVariablePitch(same or possibly greater)
Aerodynamic Forces(Effect of High Speed)
WindmillingPropeller
Negative α
TAS
Airflowdue to RotationalVelocity
WindmillingPropeller
Negative α
TAS
Airflowdue to RotationalVelocity
TR
Negative α
TAS
Airflowdue to RotationalVelocity
TR
Negative Thrust (Drag)
WindmillingPropeller
Negative α
TAS
Airflowdue to RotationalVelocity
TR
Negative Thrust (Drag)
Negative RotationalDrag (DrivingThe Propeller)
WindmillingPropeller
Negative α
TAS
Airflowdue to RotationalVelocity
TR
Negative Thrust (Drag)
Negative RotationalDrag (DrivingThe Propeller)
This may causefurther damage,
even Fire.
WindmillingPropeller
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 α”. Therefore drag at minimum.
Take-Off Swings
All Aircraft:
Torque Reaction means greater rolling
resistance on one wheel
Helical slipstream acts more on one
side of the fin than the other
Take-Off Swings
Take-Off Swings
Tail wheel aircraft only:
Asymmetric blade effect
Gyroscopic effect
Take-Off Swings
Take-Off Swings
Affect all aircraft on rotate?
Take-Off Swings
All Aircraft:
Don’t forget crosswind effect!
Centrifugal Twisting Moment
Tries to fine blade off
Aerodynamic Twisting Moment
Relative Airflow
Total Reaction
Tries to coarsen blade up
Aerodynamic Twisting Moment Windmilling
Relative Airflow
Total Reaction
Tries to fine blade off
ANY QUESTIONS?
PropellersObjectives:
2. Define Blade Angle and Blade Angle of Attack.
3. Show with the aid of a diagram the Aerodynamic
Forces acting on a Propeller Blade in flight.
5. 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.
Questions
Blade Angle of Attack is between?
a. The Chord and Relative Airflow.
b. The Rotational Velocity and the Relative Airflow.
d. The Total Reaction and the Chord.
e. Lift and Drag.
Questions
Increasing speed with a fixed pitch propeller will?
a. Be more efficient.
b. Reduce efficiency.
d. Make no difference.
e. Increase the Engine speed.
Questions
The Forces trying to alter the Propeller Blade
Angle of Attack are?
a. ATM and CTM.
b. CDM and ATM.
e. CTM and REV.
f. AOA and ATM.
Questions
The Resultant Forces that a Propeller produce are?
a. Lift and Thrust.
c. Thrust and Propeller Rotational Drag.
d. Drag and Total Reaction.
d. Drag and Thrust.