Lecture

Leading Cadet Training

Principles of Flight

5Control

Pilot ControlsA pilot has 3 main controls

to move the aircraft about its 3 axes.

Ailerons, Elevators and a Rudder

Using these controls the pilot can:

Pitch – make the nose rise or fall Roll – make one wing rise and the other fall

Yaw – make the nose move left or right

Elevators

Rudder

Ailerons

The Pitching Plane

Elevators make the aircraft nose rise or fall.

They are hinged to the trailing edge of the tailplane,

and linked to the pilots control column – ‘The Stick’

The Pitching PlaneMoving the stick forwards

lowers the elevators,

and gives an angle of attack which creates lift,

and the aircraft is tail-up, nose–down,

about its lateral axis.

Lift

Control ColumnPushed Forward

Lateral Axis

αAngle of Attack

The Pitching PlaneMoving the stick backwards

raises the elevators,creating the opposite effect,

and the aircraft is tail-down, nose–up,about its lateral axis.

Control ColumnPulled Backward

Lift

Lateral AxisαAngle of Attack

The Rolling Plane

Ailerons make the aircraft roll about its longitudinal axis.

They are hinged to the trailing edge of each wing.

and linked to the pilots control column – ‘The Stick’

Moving the stick to the left raises the LEFT aileronand depresses the RIGHT aileron.

The left aileron has a reduced angle of attackand reduced lift

The right aileron has an increased angle of attackand increased lift

The aircraft rolls to the left about its longitudinal axis.

The Rolling Plane

Control ColumnPushed LEFT

Lift

Lift

The Rolling PlaneMoving the stick to the right raises the RIGHT aileron

and depresses the LEFT aileron,creating the opposite effect,

and the aircraft rolls to the rightabout its longitudinal axis.

Control ColumnPushed RIGHT Lift

Lift

The Yawing Plane

The Rudder makes the aircraft nose move left or right.

It is hinged to the trailing edge of the fin,

and linked to the rudder pedals in the cockpit.

Moving the LEFT pedal forwards

moves the rudder to the left,

this produces a sideways force to the right.

The tail is pushed to the right

and the nose moves to the left.

The Yawing Plane

Force

Rudder PedalsLEFT Forwards

Original

Flight Path

New

Flight Path

The Yawing PlaneMoving the RIGHT pedal forwards

moves the rudder to the right,creating the opposite effect,

The tail is pushed to the left

and the nose moves to the right.

ForceRudder PedalsRIGHT Forwards

Original

Flight Path

New

Flight Path

Trimming Tabs, Flaps & Slats

The weight and position of an aircraftsCentre of Gravity can change when:

Fuel is used, Bombs dropped, Ammunition fired, etc.

The Centre of Pressure will also change due to:

Change in Power, Speed and Attitude

All these changes will affect the balance of forceson the aircraft

There are a number mechanisms that assist pilotsin these cases.

Trimming TabsHelp comes in the form of ‘trimming tabs’,

which are hinged to the trailing edgesof the elevators, ailerons and rudder.

Aileron Trim Tab

Elevator Trim Tabs

Rudder Trim Tab

Aileron Trim Tab Pull Force

Stick Force Remains

+ + + + +

+

Larger Moment Arm

Stick Force Removed

Flaps

An aircraft’s wing is designed

so that the aircraft can make its approach

at a controlled slow speed,

along a moderately steep approach path.

A well-proven solution is to add flaps

for use on the approach and landing.

FlapsFlaps are hinged surfaces

usually fitted to the trailing edge of wings

before the ailerons to increase lift.

FlapsFlaps

Blown Flap

Plain Flap(or Camber)

Split Flap

Fowler Flap

Slotted Flap

50% Increase CLMAX Critical Angle 12o

60% Increase CLMAX Critical Angle 14o

65% Increase CLMAX Critical Angle 16o

80% Increase CLMAX Critical Angle 16o

90% Increase CLMAX Critical Angle 15o

FlapsDrag Effects on Flaps

Flaps 30oFlaps 90oFlaps 60o

Flap

30o

60o

90o

Drag

Small Inc

Large Inc

V Large Inc

Lift

Large Inc

Small Inc

No Sig Inc

SlatsSlats improve handling at low speeds.

They are small aerofoils positioned along the

leading edge of each wing.

SlatsSlats

Automatic Slat

70% Increase CLMAX Critical Angle 25o

Fixed Slat

50% Increase CLMAX Critical Angle 20o

Open Slat

40% Increase CLMAX Critical Angle 20o

Kruger Slat

50% Increase LLMAX Critical Angle 25o

Droop Snoot Slat

50% Increase CLMAX Critical Angle 20o

SlatsIf the wing reaches a high angle of attack,

the slat opens.

Air can now flow between the slat and the wing.

The shape of the slot accelerates air through it improving the pattern of airflow over it.

Direction of airflow

Slat

Direction of airflow

Lift AugmentationEffects on CL

α

BASIC AEROFOIL SECTIONCL

TRAILING EDGE FLAP

LEADING EDGE FLAP

SLAT OR SLOT

CL(the ratio between

lift and dynamic pressure).

Check of UnderstandingIn position 1 the aircraft is climbing vertically.

To make the aircraft move to position 2 and then 3,Which way must the pilot move the control column?

Forward

To the right

Backward

To the left

Check of UnderstandingWhat control would a pilot use

to make an aircraft roll?

Elevator

Aileron

Rudder

Fin

Check of UnderstandingOn the diagram, what does the arrow point at?

The aileron

The elevator trimming tab

The fin

The rudder trimming tab

Check of UnderstandingWhat will happen if flaps are lowered

during the approach to land?

The stalling speed will be increased

Drag will be decreased

A higher touch-down speed is needed

Lift will be increased

Check of UnderstandingWhich of these diagrams represents a Fowler Flap?

Z

W

Y

X

Check of UnderstandingOn this cross-section of a wing,

which letter points to a slat?

R

U

S

T

Leading Cadet Training

Principles of Flight

End of Presentation