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PRINCIPLES OF FLIGHT Lift & Weight CHAPTER 1

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Page 1: 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

PRINCIPLES OF FLIGHT

Lift & Weight

CHAPTER 1

Page 2: 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

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

Page 3: 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

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

Page 4: 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

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.

Page 5: 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

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

Page 6: 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

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

Page 7: 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

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

Page 8: 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

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 ?

Page 9: 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

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

Page 10: 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

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

Page 11: 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

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.

Page 12: 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

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

Page 13: 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

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.

Page 14: 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

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

Page 15: 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

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.

Page 16: 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

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

Page 17: 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

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).

Page 18: 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

PRINCIPLES OF FLIGHT

AIR DENSITY

IF THE AIR BECOMES “THINNER” OR LESSDENSE, THE LIFT WILL DECREASE.

i.e. INCREASE IN ALTITUDE.

Page 19: 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

0°+

_

+-

LIFT = A LITTLE

PRESSURE ENVELOPE AT O°

PRINCIPLES OF FLIGHT

TOTAL REACTIONTOTAL REACTIONEQUALS LIFTEQUALS LIFT

Page 20: 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

PRESSURE ENVELOPE AT 5°

LIFT = MORE

PRINCIPLES OF FLIGHT

++

_

-

TOTAL REACTIONTOTAL REACTION

LIFTLIFT

DRAGDRAG

Page 21: 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

10°+

_

+

PRESSURE ENVELOPE AT 1O°

LIFT = MORE

PRINCIPLES OF FLIGHT

TOTAL REACTIONTOTAL REACTIONLIFTLIFT

DRAGDRAG

Page 22: 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

+

+

__

15°15°

PRESSURE ENVELOPE AT 15°

PRINCIPLES OF FLIGHT

LIFT = MORE

TOTAL REACTIONTOTAL REACTION

LIFTLIFT

DRAGDRAG

Page 23: 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

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

Page 24: 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

PRINCIPLES OF FLIGHT

HERCULES C Mk 1 – GENERAL PURPOSE WING

Page 25: 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

PRINCIPLES OF FLIGHT VIKING GLIDER – HIGH LIFT WING

Page 26: 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

PRINCIPLES OF FLIGHT

TYPHOON – HIGH SPEED WING

Page 27: 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

PRINCIPLES OF FLIGHT

F117A NIGHTHAWK – HIGH SPEED WING

Page 28: 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

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.

Page 29: 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

PRINCIPLES OF FLIGHT

GROB TUTOR – PLAIN FLAP

Page 30: 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

PRINCIPLES OF FLIGHT VC10 - FOWLER FLAP

Page 31: 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

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