PRINCIPLES OF FLIGHT CONTROLS CHAPTER 4. CONTROLS TO MAKE THE AIRCRAFT DO WHAT THE PILOT REQUIRES, THE PILOT MUST HAVE A MEANS OF CONTROL OF THE AIRCRAFT

PRINCIPLES OF FLIGHT

CONTROLS

CHAPTER 4

CONTROLS

TO MAKE THE AIRCRAFT DO WHAT THE PILOTREQUIRES, THE PILOT MUST HAVE A MEANS OF CONTROL OF THE AIRCRAFT.

THREE MAIN CONTROLS ARE PROVIDED :-

ELEVATORS

AILERONS

RUDDER

THEIR FUNCTION IS TO MOVE THE AIRCRAFTABOUT IT’S 3 AXIS.



ElevatorsElevators RudderRudder

AileronsAilerons


YAW - WHEN THE NOSE OF THE AIRCRAFT MOVES LEFT (LEFT YAW) OR RIGHT (RIGHT YAW).

THE PILOT USES THESE CONTROLS TO MAKETHE AIRCRAFT MOVE IN : -

PITCH – WHERE THE NOSE OF THE AIRCRAFT RISES (PITCHING UP) OR FALLS (PITCHING DOWN).

CONTROL USED - ELEVATORS

ROLL - WHEN ONE WING RISES THE OTHER WING FALLS. RIGHT WING DOWN IS ROLLING RIGHT.

CONTROL USED - AILERONS

CONTROL USED - RUDDER

PRINCIPLES OF FLIGHT MOVEMENT

PITCHING, ROLLING AND YAWING IS ALWAYS DESCRIBED RELATIVE TO THEPILOT RATHER THAN THE HORIZON.

THEY ARE LINKED TO THE PILOT’S CONTROL COLUMN.

THE PITCHING PLANE

PILOT USES ELEVATORS

ELEVATORS ARE USUALLY TWO MOVEABLE PARTS HINGED TO THE TRAILING EDGE OF THE TAILPLANE.

PILOT RATHER THAN THE HORIZON.


MOVING THE CONTOL COLUMN FORWARD MOVING THE CONTOL COLUMN FORWARD MOVES THE ELEVATORS DOWN, INCREASING MOVES THE ELEVATORS DOWN, INCREASING THE ANGLE OF ATTACK AND PRODUCING THE ANGLE OF ATTACK AND PRODUCING MORE LIFT.MORE LIFT.

PRODUCING MORE LIFT MOVES THE PRODUCING MORE LIFT MOVES THE AIRCRAFT AROUND IT’S LATERAL AXISAIRCRAFT AROUND IT’S LATERAL AXISAND PITCHES THE NOSE DOWN.AND PITCHES THE NOSE DOWN.

THE AIRCRAFT DESCENDS AND THE SPEEDTHE AIRCRAFT DESCENDS AND THE SPEEDINCREASES.INCREASES.


CONTROL COLUMN

ELEVATORFORCE

LATERAL AXIS

LATERAL AXIS

AIRCRAFT DESCENDSAND SPEED INCREASES

THE AIRCRAFT WILL CONTINUE TO PITCH OVERUNTIL THE CONTROL COLUMN IS PUT BACK IN

THE NUETRAL POSITION.

CONTROL COLUMNTO NUETRAL

ELEVATORFORCENUETRAL


WHATEVER THE ATTITUDE OF THE AIRCRAFT

THE REACTION TO MOVING THE CONTROLCOLUMN IS THE SAME.


C130 ELEVATORS


MOVING THE CONTROL COLUMN BACK HAS THE OPPOSITE EFFECT.


VC10 ELEVATORS


THE ROLLING PLANE

THE PILOT USES AILERONS.

AILERONS ARE USUALLY TWO MOVEABLE PARTS HINGED TO THE TRAILING EDGE OFTHE WINGS AND PLACED CLOSE TO THE WINGTIPS TO GIVE MAXIMUM LEVERAGE ABOUT THE C of G.

THEY ARE LINKED TO THE PILOT’S CONTROLCOLUMN.


THE OPPOSITE OCCURS ON THE RIGHT WING.

RAISING THE LEFT AILERON REDUCES IT’SANGLE OF ATTACK AND THEREFORE PRODUCES LESS LIFT. THIS CAUSES THE WING TO DROP.

BY MOVING THE CONTROL COLUMN TO THE LEFT, THE LEFT AILERON RISES AND THE RIGHT LOWERS.

LEFT WING RIGHT WING

WING CHORD LINE

AILERON AND WING CHORD LINE

CHANGE IN ANGLE OF ATTACK

WING CHORD LINE

AILERON AND WING CHORD LINE


THE ROLLING PLANE

STRAIGHT AND LEVEL FLIGHT

CONTROL COLUMN RIGHT

LEFT AILERON DOWN, RIGHT AILERON UP

AIRCRAFT ROLLS RIGHT


WHEN THE AIRCRAFT ACHIEVES THE REQUIRED BANK ANGLE THE CONTROL COLUMN IS PLACEDCENTRAL.

AILERONS NOW FLARE WITH THE WING ANDTHE AIRCRAFT MAINTAINS THE PRESENT BANK

ANGLE.


THIS IS KNOWN AS DIFFERENTIAL AILERON.

THE EFFECT ON EACH WING IS DIFFERENTAS THE LIFT CHANGE IS MORE PRONOUNCEDON THE DOWN MOVING AILERON. THEREFORE THE DOWN MOVING AILERONIS DEFLECTED LESS THAN THE UP MOVING.

LEFT WING RIGHT WING

UP IS USUALLY 2 TIMES THE MOVEMENT OF DOWN

ON LARGE AIRCRAFT

PRINCIPLES OF FLIGHT C130 AILERONS


THE YAWING PLANE

THE PILOT USES THE RUDDER.THE PILOT USES THE RUDDER.

ON MOST AIRCRAFT THE RUDDER IS A SINGLE CONTROL SURFACE HINGED TO THETRAILING EDGE OF THE FIN WHERE IT HASMOST EFFECT.

FIN RUDDER

TO YAW TO THE LEFT, THE PILOT PUSHES THELEFT RUDDER PEDAL WHICH DEFLECTS THERUDDER LEFT.

FIN RUDDER

THIS CAUSES AN ANGLE OF ATTACK ON THE FIN AND CAUSES A FORCE TO PUSH THE FIN RIGHT AND THEREFORE THE NOSE OF THE AIRCRAFT MOVES LEFT.

FORCE

CHORD LINE


PRINCIPLES OF FLIGHT THE YAWING PLANE

FLYING STRAIGHT

LEFT RUDDER PEDALPUSHED FORWARD,RIGHT PEDAL WILLMOVE BACK,RUDDER MOVES LEFT

PRINCIPLES OF FLIGHT THE YAWING PLANE

FORCE APPLIED TO FINAND AIRCRAFT NOSEMOVES LEFT ABOUTTHE NORMAL AXIS.i.e. LEFT YAW.

NORMAL AXIS

BRINGING THE RUDDER PEDALS BACK TO THE NUETRAL POSITION,CENTRALISES THERUDDER AND THE AIRCRAFTNOSE STOPS MOVING AND MAINTAINS THE PRESENT

HEADING.


C130 RUDDER


TRIM TABS

THE WEIGHT AND POSITION OF THE C of GCAN CHANGE IN FLIGHT DUE TO:-THE WEIGHT AND POSITION OF THE C of GCAN CHANGE IN FLIGHT DUE TO:-

BURNING FUEL

THE WEIGHT AND POSITION OF THE C of GCAN CHANGE IN FLIGHT DUE TO:-

BURNING FUEL

DROPPING BOMBS


BURNING FUEL

DROPPING BOMBS

FIRING AMMUNITION


BURNING FUEL

DROPPING BOMBS

FIRING AMMUNITION

DROPPING STORES OR MEN BY PARACHUTE


BURNING FUEL

DROPPING BOMBS

FIRING AMMUNITION


THE CENTRE OF PRESSURE WILL ALSO CHANGE DUE TO CHANGES IN:-


BURNING FUEL

DROPPING BOMBS

FIRING AMMUNITION



ENGINE POWER


BURNING FUEL

DROPPING BOMBS

FIRING AMMUNITION



ENGINE POWERALTITUDE


BURNING FUEL

DROPPING BOMBS

FIRING AMMUNITION



ENGINE POWERALTITUDESPEED


TRIM TABS

AN ENGINE FAILURE ON A MULTI ENGINE AIRCRAFT WOULD CAUSE ASYMETRIC POWER WHICH THE PILOT WOULD HAVE TO OPPOSE BY USING RUDDER.

XX

THRUSTTHRUST

THRUSTTHRUST

THRUSTTHRUST

ASYMETRIC THRUSTCAUSES YAWLEFT.

PILOTAPPLIESRIGHTRUDDER.

COUNTERSASYMETRICTHRUST.


TRIM TABS

A LATERAL UNBALANCE (POSIBLY UNEVENFUEL DISTRIBUTION) WOULD HAVE TO BE CORRECTED BY THE PILOT USING AILERON.

IN ALL THESE CONDITIONS A PILOT COULD NOT FLY FOR LONG HOLDING THESE FORCESWITHOUT SOME HELP.

THIS HELP COMES IN THE FORM OF:-

TRIMMING TABS

LEFT WINGHEAVIER THAN RIGHTWING.

TRIM TABSTHESE ARE USUALLY SMALL CONTROL SURFACES ATTACHED TO THE TRAILING EDGEOF THE AILERONS, ELEVATORS AND RUDDERWHICH BY APPLYING SMALL MOVEMENTSCAN REMOVE THE LOAD FROM THE PILOT.

EXAMPLE: ELEVATORS

TAILPLANEELEVATOR

TRIM TAB



SO TAKING THE LOAD OFF THE PILOT.

BY MOVING THE TRIM TAB DOWN, THE INCREASE IN ANGLE OF ATTACK WILL CAUSE THE ELEVATOR FORCE TO BE COUNTERACTED.

IF THE PILOT HAS TO MAINTAIN A BACKWARDS PRESSURE ON THE CONTROL COLUMN TO MAINTAIN LEVEL FLIGHT. DOWNWARD FORCE TO KEEP

AIRCRAFT NOSE UP

DOWNWARD FORCE TO KEEP AIRCRAFT NOSE UP

SMALLER FORCE TO BALANCEELEVATOR FORCE

DIFFERENT LEVERAGE ARMS

PRINCIPLES OF FLIGHT TRIM TABSAILERON AND RUDDER TRIM TABS WORK ON THE SAME PRINCIPLE.

TRIMTABS


TRIM TABS

ON SOME AIRCRAFT THERE ARE NO ELEVATORTRIM TABS.

INSTEAD THE WHOLE TAILPLANE MOVES TOTAKE OUT ANY LOADS FROM THE PILOT.

THIS CAN BE ACHIEVED BY A MECHANICALLINKAGE OR BY HYDRAULIC CONTROL.


TRIM TABS MOVINGTAILPLANE


TRIM TABS

MOVING TAILPLANE


HIGH LIFT DEVICES

THESE DEVICES IMPROVE THE LIFTCAPABILITIES OF THE WING AND IMPROVE TAKE-OFF AND LANDING PERFORMANCE.

TYPES:- FLAPS

SLATS

SLOTS

KRUGER FLAPS

DROOP SNOOT FLAPS

FLAPS - LANDINGPRINCIPLES OF FLIGHT

FOR A SAFE LANDING THE AIRCRAFT MUST BE ABLE TO FLY SLOW ENOUGH TO BE ABLE TO STOP ON THE RUNWAY AND HAVE A STEEP APPROACH ANGLE TO LET THE PILOT SEE THE RUNWAY.

AN AIRCRAFT WING IS DESIGNED FOR A SPECIFIC ROLE, NOT USUALLY FOR LANDING.

THEREFORE TO ACHIEVE A SAFE LANDING THE WING HAS TO BE MODIFIED.

THIS IS ACHIEVED BY USING: - FLAPS.

FLAPS ARE ATTACHED TO THE TRAILING EDGE OF THE WING AND ARE EXTENDED TO INCREASE THE WING AREA AND CHORD LENGTH.


LANDING FLAP

PRINCIPLES OF FLIGHT FLAPS - TAKE-OFF

A SMALL AMOUNT OF FLAP WILL PRODUCE EXTRA LIFT BUT LITTLE DRAG AND SO ALLOWA SHORTER TAKE-OFF DISTANCE.

TAKE-OFF FLAP


FLAPS

GENERAL WING SECTION

SIMPLE OR PLAIN FLAP

SPLIT FLAP

FOWLER FLAP

TYPES OF FLAP


FLAPS

WHEN THE FLAPS ARE “UP” THEY ARE FLUSH WITH THE WING AND WHEN “DOWN” THEY CAN BE UP TO 90° TO THE WING.



UP TO 60° THE INCREASE IN LIFT IS LARGE AND THE INCREASE IN DRAG SMALL.

FROM 60° TO 90° THE INCREASE IN LIFT ISSMALL AND THE INCREASE IN DRAG IS LARGE.


FLAPS

A SMALL AMOUNT OF FLAP WILL ALLOW A SLOWER STALLING SPEED BUT NOT GIVE AN INCREASE IN APPROACH ANGLE.

A LARGE AMOUNT OF FLAP WILL GIVE ASTEEPER APPROACH ANGLE AND WILL ALLOWA SLOWER STALLING SPEED.


FLAPSFLAPS

15° LARGE INCREASE15° LARGE INCREASEIN LIFT. VERY SMALL IN LIFT. VERY SMALL INCREASE IN DRAG.INCREASE IN DRAG.

60° SOME INCREASE 60° SOME INCREASE IN LIFT. LARGE IN LIFT. LARGE INCREASE IN DRAGINCREASE IN DRAG

90° VERY SMALL90° VERY SMALLINCREASE IN LIFT.INCREASE IN LIFT.HUGE INCREASEHUGE INCREASEIN DRAG.IN DRAG.


FLAPS

FULL FLAP – GOOD VIEW OF LANDING AREAAND REDUCED STALLING SPEED

NO FLAP-POOR FORWARD VIEW


FLAPS GROB TUTOR – PLAIN FLAP


FLAPS

SPITFIRE – SPLIT FLAP

PRINCIPLES OF FLIGHT FLAPS

VC10 – FOWLER FLAP

PRINCIPLES OF FLIGHT FLAPS

BOEING 747 – DOUBLE SLOTTED FOWLER FLAP


SLATSSLATS ARE ANOTHER DEVICE WHICH CAN IMPROVE LOW SPEED HANDLING AND STALL SPEED.

THEY ARE SMALL AEROFOIL SECTIONS ON THE LEADING EDGE OF WINGS, WHICH WHENEXTENDED INCREASE LIFT AND AIRFLOWCONTROL.

SLATS

THE DIAGRAM SHOWS AN AUTOMATIC SLATWHICH IS HELD IN THE CLOSED POSITION BY SPRINGS.

SLATSPRINCIPLES OF FLIGHT


SLATS

WHEN THE WING REACHES A HIGH ANGLE OF ATTACK, THE LIFT FORCES ON THE SLAT OVERCOME THE SPRINGS AND THE SLATS EXTEND.

THE AIR CAN NOW FLOW BETWEEN THE SLATAND THE WING, CAUSING THE AIR TO ACCELERATE OVER THE WING SO IMPROVINGTHE AIRFLOW OVER THE WING.

- AUTOMATIC SLAT


SLATS

USUALLY THE WING CRITICAL ANGLE IS 15°, BUT WITH SLATS THIS CAN INCREASE TO 25°.

THIS CAN BE A DIFFERENCE OF 20-25 KTS IN THE STALLING SPEED.

PRINCIPLES OF FLIGHT SLATSON MOST LARGE AIRCRAFT THE SLATS ARE NOT AUTOMATIC BUT OPERATED FROM THE FLIGHT DECK IN CONJUNCTION WITH THE FLAPS FOR TAKE-OFF AND LANDING.


LOCKHEED TRISTAR

SLATS

PRINCIPLES OF FLIGHT SLOTS

SLOT

AS THE ANGLE OF ATTACK OF THE WING INCREASES THE EFFECT OF THE AIRFLOWTHROUGH THE SLOT INCREASES AND SMOOTHS THE AIRFLOW OVER THE TOPSURFACE OF THE WING, SO REDUCING TURBULENCE.

A SLOT CAN INCREASE THE CRITICAL ANGLETO ABOUT 20°.


KRUGER FLAPS

THESE ARE SIMILAR TO SLATS AND HAVE THE SAME EFFECT, BUT ARE HINGED TO THE LEADINGEDGE OF THE WING AND EXTEND FORWARD.

INCREASES THE CRITICAL ANGLE TO 25o


KRUGER FLAPS


DROOP SNOOT FLAP

INCREASES THE CRITICAL ANGLE TO 20o

Documents

PRINCIPLES OF FLIGHT CONTROLS CHAPTER 4. CONTROLS TO MAKE THE AIRCRAFT DO WHAT THE PILOT REQUIRES, THE PILOT MUST HAVE A MEANS OF CONTROL OF THE AIRCRAFT