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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


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Propellers

(Terminology)

Induced Flow

Airflow due


RelativeAirflow

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Propellers

(Terminology)

Induced Flow

Airflow due


RelativeAirflow

ChordLine

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Propellers

(Terminology)

Induced Flow

Airflow due


RelativeAirflow

= AofA

ChordLine

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Propellers

(Terminology)

Induced Flow

Airflow due


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


At Zero

Airspeed

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Induced Flow

Airflow due


(Same)

At a Forward

Airspeed

=Total InflowTAS +

-

Effect of Airspeed

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Effect of Airspeed

Induced Flow

Airflow due


(Same)

=Total InflowTAS +

-

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


RAF

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Aerodynamic

Forces

Total Inflow

Airflow due


RAF

Total

Reaction

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Aerodynamic

Forces

Total Inflow

Airflow due


RAF

Lift

Drag

Total

Reaction

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Aerodynamic

Forces

Total Inflow

Airflow due


RAF

Total

Reaction

Thrust

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Aerodynamic

Forces

Total Inflow

Airflow due


RAF

Total

Reaction

Thrust

Prop

Rotational

Drag

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Aerodynamic Forces

(Effect of High Speed)

TAS+Induced Flow

Airflow due


RAF

Total

Reaction

Thrust

Slow

Speed

Fixed

Pitch

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TAS+Induced Flow

Airflow due


RAF

Total

Reaction

Thrust

High

Speed

Fixed

Pitch

Aerodynamic Forces


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TAS+Induced Flow

Airflow due


RAF

Total

Reaction

Thrust

High

Speed

Fixed

Pitch

Aerodynamic Forces


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TAS+Induced Flow

Airflow due


RAF

Total

Reaction

Thrust

High

Speed

Fixed

Pitch

Aerodynamic Forces


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TAS+Induced Flow

Airflow due


RAF

NB: Rotational Drag

reduced, RPM ?

Thrust

High

Speed

Fixed

Pitch

Aerodynamic Forces


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TAS+Induced Flow

Airflow due


RAF

NB: Rotational Drag

reduced, RPM increases.

Dont exceed limits.

Thrust

High

Speed

Fixed

Pitch

Aerodynamic Forces


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TAS+Induced Flow

Airflow due


RAF

Total

Reaction

Thrust

Slow

Speed

Variable

Pitch

Aerodynamic Forces


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Faster TAS+Induced Flow

Airflow due


RAF

Total

Reaction

Thrust(eventually

reduces) High

Speed

Variable

Pitch(same or possibly greater)

Aerodynamic Forces


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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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pof lo5 p1

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