principles of flight lift & weight chapter 1. principles of flight centre of gravity the point...
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PRINCIPLES OF FLIGHT
Lift & Weight
CHAPTER 1
PRINCIPLES OF FLIGHT
CENTRE OF GRAVITY
THE POINT ON A BODY WHERE THE TOTAL WEIGHT OF THAT BODY IS SAID TO ACT.
WEIGHT WEIGHT WEIGHT
CENTREOFGRAVITY
PRINCIPLES OF FLIGHT
MOMENT OR LEVERAGE
11TONTON
11 TONTON
2 METRES 2 METRES
THE LEFT WEIGHT IS BALANCED WITH THE RIGHT WEIGHT ABOUT THE FULCRUM.
EACH WEIGHT HAS MOMENT OF IT’S WEIGHT TIMES IT’S DISTANCE FROM THE FULCRUM.
FULCRUM
1 TON X 2 METRES = 2 TONMETRES
PRINCIPLES OF FLIGHT
1 METRE 3 METRES
MOMENT OR LEVERAGE
1/31/3 TONTON
11 TONTON
FULCRUM
WILL THE BEAM BE BALANCED ? YES.
1 TON X 1 METRE = 1 TONMETRE
1/3 TON X 3 METRES = 1 TONMETRE
THEREFORE IT CAN BE SEEN THAT A SMALL WEIGHT CAN BALANCE A LARGE WEIGHT IF IT HAS ENOUGH LEVERAGE OR MOMENT.
PRINCIPLES OF FLIGHT
VECTORS
WHEN A FORCE ACTS AT AN ANGLE AWAY FROM THE HORIZONTAL OR VERTICAL IT CAN BE BROKEN DOWN INTO HORIZONTAL ANDVERTICAL VECTORS.
FORCE
VERTICALCOMPONENT
HORIZONTALCOMPONENT
THIS FORCE IS KNOWN AS THE RESULTANT FORCEOF THE HORIZONTALAND VERTICAL COMPONENTS
RESULTANT
PRINCIPLES OF FLIGHT
NEWTON’S 3RD LAW
PRINCIPLES OF FLIGHT
THE BORING BITS
NEWTON’S 3RD LAW
PRINCIPLES OF FLIGHT
THE BORING BITS
TO EVERY ACTION THERE IS AN EQUAL AND OPPOSITE REACTION
NEWTON’S 3RD LAW
PRINCIPLES OF FLIGHT
THE BORING BITS
TO EVERY ACTION THERE IS AN EQUAL AND OPPOSITE REACTION
A CAR SITS ON THE ROAD AND IS SUPPORTED BY IT
PRINCIPLES OF FLIGHT
NEWTON’S 3RD LAW
PRINCIPLES OF FLIGHT
THE BORING BITS
TO EVERY ACTION THERE IS AN EQUAL AND OPPOSITE REACTION
A BOAT SITS ON WATER AND IS SUPPORTED BY IT
PRINCIPLES OF FLIGHT
NEWTON’S 3RD LAW
THE BORING BITS
TO EVERY ACTION THERE IS AN EQUAL AND OPPOSITE REACTION
AN AIRCRAFT WHEN FLYING IS IN THE AIR
AIRAIR IS A SUBSTANCE JUST LIKE THE ROAD AND WATER
WHAT SUPPORTS IT ?
PRINCIPLES OF FLIGHT
IF AIRSPEED INCREASES THEN AIRPRESSURE DECREASES
AIRSPEED INCEASES TO GET SAME MASS OF AIR THROUGH RESTRICTION
WHAT HAPPENS AT B ?
AIRSPEED AND PRESSURE AT A AND CARE THE SAME
A B C
PRINCIPLES OF FLIGHT
NOW APPLY THIS TO AN AIRCRAFT WING
BERNOULLI’S PRINCIPLES
THE BORING BITS
WHEN AIR IS MOVING IN A STREAMLINED FLOW
IF THE AIRSPEED INCREASES THE AIR PRESSURE DECREASES
AND IF THE AIRSPEED DECREASES THE AIR PRESSURE
INCREASES.
PAPER DEMOS
THIS IS KNOWN AS LIFT
PRINCIPLES OF FLIGHT AIRCRAFT WING
UNDISTURBED AIRFLOW
AIRFLOW BETWEEN THE UNDISTURBED AIR AND THE TOP SURFACE OF THE WING IS JUSTLIKE A RESTRICTION.
THEREFORE THE AIRFLOW ABOVE THE WING INCREASES IN SPEED AND THE AIR PRESSUREDROPS, CAUSING THE WING TO RISE.
PRINCIPLES OF FLIGHT
IN REALITY THE WING IS NOT USUALLYHORIZONTAL TO THE AIRFLOW.
THIS CAUSES A DOWNWASH WHICH ADDSTO THE LIFT OF THE WING, BUT NOT AS MUCHAS THE UPPER SURFACE OF THE WING.
UNDISTURBED AIRFLOW
DOWNWASH
PRINCIPLES OF FLIGHT
LIFT FORCES ON A TYPICAL WING IN FLIGHT
ONCOMING AIR
THE LENGTH OF THE ARROW INDICATES THEAMOUNT OF LIFT BEING PRODUCED.
MOST LIFT IS PRODUCED ABOUT 1/3 FROMTHE LEADING EDGE OF THE WING.
PRINCIPLES OF FLIGHT
RATHER THAN WORK WITH LOTS OF SMALLFORCES, THE TOTAL LIFT ON A WING ISDEEMED TO WORK THROUGH A SINGLE POINT.
RATHER THAN WORK WITH LOTS OF SMALLFORCES, THE TOTAL LIFT ON A WING ISDEEMED TO WORK THROUGH A SINGLE POINT.
THIS POINT IS CALLED :-
THE CENTRE OF PRESURE
PRINCIPLES OF FLIGHT
CHORD LINE
ONCOMING AIRFLOW
DEFINITIONS
CHORD LINE IS A LINE JOINING THE LEADING EDGE TO THE TRAILING EDGE OF THE WING.
MEAN CAMBER LINE
ONCOMING AIRFLOW
THE MEAN CAMBER LINE IS A LINE EQUI-DISTANT FROM THE TOP AND BOTTOM OF THE WING.
PRINCIPLES OF FLIGHT
SEVERAL FACTORS AFFECT THE AMOUNT OF LIFT PRODUCED BY A WING.
AIRSPEED.
INCREASE IN AIRSPEED WILLCAUSE AN INCREASE IN LIFT.
LIFT INCREASES BY THE SQAUREOF THE SPEED.
2 x SPEED = 4 x LIFT
3 X SPEED = 9 x LIFT
PRINCIPLES OF FLIGHT
ANGLE OF ATTACK
CHORD LINE
ONCOMING AIRFLOW
ANGLE OF ATTACK
ANGLE OF ATTACK IS THE ANGLE BETWEEN THE CHORD LINE AND THE ONCOMING AIRFLOW.
IF THE ANGLE OF ATTACK INCREASES THE LIFT INCREASES UP TO AN ANGLE OF 15°. AFTER THIS THE LIFT RAPIDLY DECREASES LEADING TO A STALL (TO BE COVERED LATER).
PRINCIPLES OF FLIGHT
AIR DENSITY
IF THE AIR BECOMES “THINNER” OR LESSDENSE, THE LIFT WILL DECREASE.
i.e. INCREASE IN ALTITUDE.
0°+
_
+-
LIFT = A LITTLE
PRESSURE ENVELOPE AT O°
PRINCIPLES OF FLIGHT
TOTAL REACTIONTOTAL REACTIONEQUALS LIFTEQUALS LIFT
PRESSURE ENVELOPE AT 5°
LIFT = MORE
PRINCIPLES OF FLIGHT
++
_
-
5°
TOTAL REACTIONTOTAL REACTION
LIFTLIFT
DRAGDRAG
10°+
_
+
PRESSURE ENVELOPE AT 1O°
LIFT = MORE
PRINCIPLES OF FLIGHT
TOTAL REACTIONTOTAL REACTIONLIFTLIFT
DRAGDRAG
+
+
__
15°15°
PRESSURE ENVELOPE AT 15°
PRINCIPLES OF FLIGHT
LIFT = MORE
TOTAL REACTIONTOTAL REACTION
LIFTLIFT
DRAGDRAG
PRINCIPLES OF FLIGHT
WING SHAPE AND AREA
THE SHAPE AND WING SIZE (AREA) WILLAFFECT THE AMOUNT OF LIFT. THESE AREDECIDED AT THE AIRCRAFT DESIGN STAGE,DEPENDING ON THE ROLE OF THE AIRCRAFT
EXAMPLES
PRINCIPLES OF FLIGHT
HERCULES C Mk 1 – GENERAL PURPOSE WING
PRINCIPLES OF FLIGHT VIKING GLIDER – HIGH LIFT WING
PRINCIPLES OF FLIGHT
TYPHOON – HIGH SPEED WING
PRINCIPLES OF FLIGHT
F117A NIGHTHAWK – HIGH SPEED WING
PRINCIPLES OF FLIGHT
LIFT ON OCCASIONS AIRCRAFT NEED TO SLOW DOWN, BUT STILL REQUIRE LIFT.HOW CAN THIS BE DONE ?
IF THE CAMBER OR AREA OF THE WINGINCREASES, THEN LIFT INCREASES.
THIS CAN BE ACHIEVED BY USING FLAPS.
PRINCIPLES OF FLIGHT
GROB TUTOR – PLAIN FLAP
PRINCIPLES OF FLIGHT VC10 - FOWLER FLAP
PRINCIPLES OF FLIGHT
LIFT AND WEIGHT IN STRAIGHT AND LEVEL FLIGHT
IN STEADY STRAIGHT AND LEVEL FLIGHT, THE LIFT FORCE EQUALS THE FORCE OF GRAVITY WORKING ON THE AIRCRAFT (IT’S WEIGHT).
LIFT equals WEIGHT
WEIGHT equals LIFT
IF THE LIFT IS GREATER THAN THE WEIGHT THEN THE AIRCRAFT WILL CLIMB.
LIFT greater than WEIGHT
IF THE WEIGHT IS GREATER THAN THE LIFT THEN THE AIRCRAFT WILL DESCEND.
WEIGHT greater than LIFT