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Title: Flight Controls Note Part 1
Description: EASA PART 66 MODULE 11 - FLIGHT CONTROLS NOTES PART 1
Description: EASA PART 66 MODULE 11 - FLIGHT CONTROLS NOTES PART 1
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1/28/2014
Module 11A
TURBINE AEROPLANE
AERODYNAMICS, STRUCTURES AND
SYSTEMS
Theory of Flight and Controls
INTRODUCTION
Aircraft are equipped with both fixed aerofoils and
moveable aerofoil control surfaces
...
The moveable aerofoils allow the aircraft to change
attitude around the 3 axis or to augment the lift generated
during take off and landing
...
...
Eg
...
ON SOME AIRCRAFT SLATS ARE DEPLOYED AUTOMATICALLY BY
AERODYNAMIC FORCES, NORMALLY THOSE ASSOCIATED WITH HIGH
ANGLES OF ATTACK
...
WHEN THE ANGLE OF ATTACK DECREASES THE AIR PRESSURE ACTING
ON THE FRONT OF THE SLAT RETRACTS IT BACK INTO THE LEADING
EDGE
...
THESE FLAPS ARE USED IN CONJUNCTION WITH TRAILING
EDGE FLAPS
...
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LEADING EDGE FLAPS
ACTUATOR
LEADING EDGE
HINGE
LEADING EDGE FLAPS
ACTUATOR EXTENDS
LEADING EDGE DROOPS
GREATER CURVATURE OF AEROFOIL GIVING GREATER LIFT
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KRUEGER FLAPS
THE SWEPT WINGS OF LARGER JET AIRCRAFT GENERATE
LITTLE LIFT AT LOW SPEED, LEADING EDGE FLAPS CALLED
KRUEGER FLAPS OVERCOME THIS PROBLEM
...
WHEN DEPLOYED IT EXTENDS DOWNWARDS AND
FORWARDS TO ALTER THE WING PROFILE
...
ACTUATOR
LEADING EDGE
KREUGAR FLAP IN STOWED POSITION
KRUEGER FLAP
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GREATER CURVATURE ON UPPER
SURFACE
ACTUATOR EXTENDS
FLAP LOWERS
KRUEGER FLAP
PITCHING MOMENT ON FLAP EXTENSION
WHEN TRAILING EDGE FLAPS INITIALLY DEPLOY, THE WING
WILL GENERATE MORE LIFT
...
AS THE FLAPS TRAVEL FURTHER THE CENTRE OF LIFT MOVES
BACKWARDS DUE TO THE INCREASE IN WING AREA AND
MORE DRAG IS GENERATED FROM THE TRAILING EDGE
...
THIS IS COUNTERACTED BY A CORRESPONDING MOVEMENT
OF THE ELEVATORS
...
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SPOILERS
• Reduce or spoil the lift
• Speed brakes
• Flight spoilers
– Used in flight to assist rolling
– Some aircraft use as primary flight controls (737)
– Speed brakes (use for quick decent)
• Ground spoilers
– Increase drag on landing to slow down aircraft
– Spoil all lift
– Reduce braking force
Speedbrake on BAE 146-300
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Parachute on Military Aircrafts
Space Shuttle use Parachute and Split Rudder
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Airflow Control- Wing Fence
•
•
•
•
To control spanwise flow
Usually fitted on swept wing aircraft
Fitted around mid-span
Straighten the airflow over the aileron and
near wingtip
• less air spillage from beneath the wing,
therefore less drag
Air flow over swept wing
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WING FENCE
WING FENCE
WING NOTCH
THIS IS SIMPLY AN INCREASE IN WING CHORD ON THE
OUTER PORTION OF THE WING AND IT FUNCTIONS IN THE
SAME MANNER AS A WING FENCE
...
THIS WALL STRAIGHTENS THE SPAN-WISE FLOW
OF AIR
...
VORTEX GENERATORS ARE SMALL PLATES OR WEDGES
PROJECTING UP FROM EITHER SURFACE OF AN AEROFOIL
INTO THE FREE AIRFLOW
...
THIS ACTION MOVES THE TRANSITION POINT REARWARDS
TOWARDS THE TRAILING EDGE
...
THESE ENSURE THAT THE INNER WING STALLS AS THE
AEROFOIL APPROACHES THE STALLING ANGLE
...
AS THE INNER WINGS LIFT IS DESTROYED THE AIRCRAFT
WILL START TO PITCH NOSE DOWN
...
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LEADING EDGE STALL STRIPS
SMOOTH AIRFLOW
STALL STRIP
TURBULENT AIRFLOW
INDUCED DRAG
INDUCED DRAG IS A RESULT OF THE LIFT BEING GENERATED
BY THE DIFFERING PRESSURE BETWEEN THE UPPER AND
LOWER AEROFOIL SURFACES
...
AIRFLOW OVER THE LOWER AEROFOIL SURFACE TENDS TO
FLOW OUTWARDS TO THE WING TIPS
...
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WING TIP VORTICES
AIRFLOW ACROSS UPPER SURFACE
WING TIP VORTICES
AIRFLOW ACROSS LOWER SURFACE
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WING TIP VORTICES
TWO AIRFLOW’S MEET FORMING TRAILING EDGE VORTICES
WING TIP VORTICES
THE HIGHER PRESSURE OF THE LOWER SURFACE WILL TEND TO FLOW OVER THE WING TIP TO
THE LOWER PRESSURE ON TOP OF THE WING, CREATING WING TIP VORTICES
...
THEY ARE VISIBLE WHEN MOISTURE IN THE AIR CONDENSES DUE
TO THE DIFFERENTIAL PRESSURES
...
WHEN VIEWED FROM THE REAR OF THE AIRCRAFT THESE
VORTICES ROTATE CLOCKWISE AROUND THE PORT WING AND
ANTI CLOCKWISE AROUND THE STARBOARD WING
...
WING TIP VOTICES
VIEWED FROM THE REAR
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WINGTIP VORTICES
WINGLETS
THESE ARE SMALL FIN LIKE AEROFOILS THAT PROTRUDE
UPWARDS FROM THE WING TIPS
...
SOME AIRCRAFT HAVE WINGLETS THAT ALSO PROJECT
DOWNWARDS
...
BY PRODUCING TWO SMALLER VORTICES THEY
SUBSTANTIALLY REDUCE INDUCED DRAG
...
THEY ARE ADJUSTED BY EITHER A TRIM-WHEEL, TRIM
LEVER OR SWITCH WITH THE TAB BEING ACTUATED BY
MECHANICAL, ELECTRIC OR HYDRAULIC MEANS
...
...
THE ACTUATOR EXTENDS AND THE TAB MOVES
...
DOWN
SERVO TRIM TABS
THEY ARE POSITIONED ON THE TRAILING EDGE OF THE PRIMARY
CONTROL SURFACES AND ALSO KNOWN AS FLIGHT TABS
...
THEY ACT AS A POWER BOOSTER AS THE CREW EFFORT IS ONLY
REQUIRED TO DEFLECT THE SERVO TAB INTO THE AIRFLOW
...
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SERVO TRIM TABS
THE CONTROL SURFACE WILL CONTINUE TO MOVE UNTIL
THE AERODYNAMIC FORCES ON THE TAB AND THE
SURFACE ARE BALANCED
...
MOVING THE SERVO TAB UP WILL MOVE THE CONTROL
SURFACE DOWN
...
THE FLIGHT DECK CONTROLS ARE CONNECTED TO THE
PRIMARY CONTROL SURFACES
...
THE TAB WILL REMAIN IN THE SAME POSITION RELATIVE
TO THE FIXED AEROFOIL
...
BALANCE TABS
AERODYNAMICALLY THE TAB IS MOVING IN THE
OPPOSITE DIRECTION TO THE MOVEABLE CONTROL
SURFACE AND THEREFORE ASSISTS THE CONTROL
SURFACES TO MOVE
...
A LINEAR ACTUATOR WILL BE LOCATED IN THE TAB
CONTROL MECHANISM AND WILL BE ACTUATED FROM
THE FLIGHT DECK
...
THE LINK ROD IS CONNECTED DIRECT TO THE FIXED AEROFOIL
...
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BALANCE TABS
LINEAR ACTUATOR
BY ADDING A LINEAR ACTUATOR THE TAB CAN ALSO BE
USED AS A TRIM TAB
...
THE TAB WILL MOVE RELATIVE TO THE PRIMARY CONTROL
SURFACE AND IN THE SAME DIRECTION
...
THIS GIVES THE CONTROL “FEEL” TO PREVENT THE
POSSIBILITY OF THE AIRFRAME BEING OVER-STRESSED
...
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ANTI BALANCE TABS
LINEAR ACTUATOR
BY ADDING A LINEAR ACTUATOR THE TAB CAN ALSO BE
USED AS A TRIM TAB
...
THE SPRING TAB OVERCOMES THIS BY PROGRESSIVELY
INCREASING THE AERODYNAMIC ASSISTANCE IN MOVING
THE CONTROL SURFACES AS THE AIRCRAFT SPEED
INCREASES
...
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SPRING TABS
AT LOW AIRSPEEDS THE AERODYNAMIC LOADS ARE SMALL
AND WILL INCREASE AS SPEED INCREASES
...
THE TAB WILL REMAIN IN THE SAME RELATIVE POSITION
TO THE PRIMARY CONTROL SURFACE AND WILL NOT
PROVIDE ANY ADDITIONAL AERODYNAMIC ASSISTANCE IN
MOVING THE CONTROL SURFACE
...
MOVEMENT OF THE FLIGHT DECK CONTROLS CAUSES THE
TORQUE TUBE TO TWIST (OR THE SPRING TO COMPRESS)
RESULTING IN THE DEFLECTION OF THE SPRING TAB
...
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SPRING TABS
HORN BALANCE
CONTROL
LINKAGE
SPRING BOX
TRIM TAB
LINK ROD
FIXED AEROFOIL SURFACE
CONTROL SURFACE
SPRING TABS
CONTROL INPUT
WITH LOW AERODYNAMIC LOADS, THE TAB WILL MOVE
RELATIVE TO THE CONTROL SURFACE
...
THE TAB WILL MOVE OPPOSITE TO THE DIRECTION OF THE
CONTROL SURFACE
...
WHEN LOADS DISTORT THE AEROFOIL THE CONTROL
SURFACE CAN LAG BEHIND AND CREATE AN OPPOSING
FORCE
...
THE CONTROL SURFACE WILL AGAIN LAG BEHIND IN THE
OPPOSITE DIRECTION
...
THESE FORCES CAN BE SEVERE ENOUGH TO EVENTUALLY BREAK THE
STRUCTURE
...
FLUTTER CAN BE PREVENTED BY MOVING THE C of G IN LINE OR
SLIGHTLY IN FRONT OF THE CONTROL SURFACE HINGE LINE
...
MASS BALANCE
•THIS IS NORMALLY ACHIEVED BY ADDING A NUMBER OF
HIGH DENSITY WEIGHTS EITHER:
•WITHIN (OR ON) THE LEADING EDGE OF THE
CONTROL SURFACE
...
•THIS PROCEDURE FOR ADDING THE WEIGHTS IS CALLED
MASS BALANCING
...
ON A SINGLE PROPELLER AIRCRAFT, FOR EXAMPLE, IT MAY
HAVE A TENDENCY TO ROLL IN THE OPPOSITE DIRECTION TO
THE ENGINES TORQUE
...
THE RUDDER MAY HAVE AN OFFSET TO COUNTERACT A
YAWING MOMENT
...
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CONTROL SURFACE BIAS
ON MANUAL CONTROLS, CONTROL SURFACE BIAS IS
ACHIEVED BY ADJUSTING THE INPUT CABLES OR RODS
...
ONCE THE BIAS IS SET THE TRIM GAUGE IN THE COCKPIT
WOULD THEN BE SET TO ZERO
...
THIS IS REFERRED TO AS AERODYNAMIC BALANCING AND
IS ACHIEVED IN 3 WAYS:
HORN BALANCE
...
PRESSURE BALANCING
...
THE AIRFLOW ACTING ON THIS PROJECTED SURFACE WILL
ASSIST THE MOVEMENT OF THE CONTROL
...
THIS ACTION IS BALANCED BY THE AERODYNAMIC FORCES
THAT THE CONTROL SURFACE GENERATES
...
HORN BALANCE
HINGE LINE
HORN
RUDDER
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HORN BALANCE
AERODYNAMIC FORCES ON THE RUDDER TEND TO
TURN THE RUDDER CLOCKWISE
RUDDER
HINGE LINE
AIRFLOW
HORN
SMALLER AERODYNAMIC FORCES ON THE HORN TEND
TO PUSH THE RUDDER ANTI-CLOCKWISE
ANTI-
THE RESULTANT IS REDUCED PILOT EFFORT AND CONTROL LOADS
INSET HINGE
THIS IS SIMILAR TO HORN BALANCE AND HAS THE SAME
EFFECT
...
THE FORWARD EDGES OF THE CONTROL SURFACE ARE
PROJECTED INTO THE AIRFLOW WHEN THE CONTROLS
ARE MOVED FROM THE NEUTRAL POSITION
...
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INSET LINE
HINGE
HINGE
CONTROL SURFACE
HINGE LINE
AIRFLOW
BALANCE PANELS
BALANCE PANELS ARE USED IN AILERON SYSTEMS
...
WHEN THE CONTROL SURFACE IS DEFLECTED FROM THE
NEUTRAL, THE PRESSURE CHANGES ABOVE AND BELOW
THE AEROFOIL ARE USED TO ASSIST ITS MOVEMENT
...
THE HIGHER PRESSURE BELOW THE BALANCE PANEL ASSISTS
WITH THE CONTROL MOVEMENT ABOUT THE AILERON HINGE
...
INCREASED PRESSURE ABOVE BALANCE PANEL ASSISTS WITH
THE CONTROL MOVEMENT ABOUT THE AILERON HINGE
Title: Flight Controls Note Part 1
Description: EASA PART 66 MODULE 11 - FLIGHT CONTROLS NOTES PART 1
Description: EASA PART 66 MODULE 11 - FLIGHT CONTROLS NOTES PART 1