Download lift = a little pressure envelope at o° principles of flight total reaction

PRINCIPLES OF FLIGHT
CHAPTER 1
Lift & Weight
PRINCIPLES OF FLIGHT
CENTRE OF GRAVITY
THE POINT ON A BODY WHERE THE TOTAL
WEIGHT OF THAT BODY IS SAID TO ACT.
CENTRE
OF
GRAVITY
WEIGHT
WEIGHT
WEIGHT
PRINCIPLES OF FLIGHT
MOMENT OR LEVERAGE
2 METRES
2 METRES
1
TON
1
TON
FULCRUM
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.
1 TON X 2 METRES = 2 TONMETRES
PRINCIPLES OF FLIGHT
1 METRE
MOMENT OR LEVERAGE
3 METRES
1
TON
1/3
TON
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 AND
VERTICAL VECTORS.
RESULTANT
FORCE
THIS FORCE IS KNOWN AS
THE RESULTANT FORCE
OF THE HORIZONTAL
AND VERTICAL COMPONENTS
VERTICAL
COMPONENT
HORIZONTAL
COMPONENT
PRINCIPLES OF FLIGHT
THE BORING BITS
NEWTON’S 3RD LAW
TO EVERY ACTION THERE IS AN EQUAL AND
OPPOSITE REACTION
A CAR SITS ON THE ROAD AND IS SUPPORTED BY IT
PRINCIPLES OF FLIGHT
THE BORING BITS

NEWTON’S 3RD
LAW
TO EVERY ACTION THERE IS AN EQUAL AND
OPPOSITE REACTION
A BOAT SITS ON WATER AND IS SUPPORTED BY IT
PRINCIPLES OF FLIGHT

THE BORING BITS
NEWTON’S 3RD LAW
TO EVERY ACTION THERE IS AN EQUAL AND
OPPOSITE REACTION
AN AIRCRAFT WHEN FLYING IS IN THE AIR
WHAT SUPPORTS IT ?
AIR
AIR IS A SUBSTANCE JUST LIKE THE ROAD AND WATER
PRINCIPLES OF FLIGHT
AIRSPEED AND PRESSURE AT A AND C
ARE THE SAME
A
B
C
WHAT HAPPENS AT B ?
AIRSPEED INCEASES TO GET SAME MASS OF
AIR THROUGH RESTRICTION
IF AIRSPEED INCREASES THEN AIR
PRESSURE DECREASES
PRINCIPLES OF FLIGHT
THE BORING BITS
BERNOULLI’S PRINCIPLES
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
NOW APPLY THIS TO AN AIRCRAFT WING
PRINCIPLES OF FLIGHT
AIRCRAFT WING
UNDISTURBED AIRFLOW
AIRFLOW BETWEEN THE UNDISTURBED AIR
AND THE TOP SURFACE OF THE WING IS JUST
LIKE A RESTRICTION.
THEREFORE THE AIRFLOW ABOVE THE WING
INCREASES IN SPEED AND THE AIR PRESSURE
DROPS, CAUSING THE WING TO RISE.
PRINCIPLES OF FLIGHT
IN REALITY THE WING IS NOT USUALLY
HORIZONTAL TO THE AIRFLOW.
UNDISTURBED AIRFLOW
DOWNWASH
THIS CAUSES A DOWNWASH WHICH ADDS
TO THE LIFT OF THE WING, BUT NOT AS MUCH
AS THE UPPER SURFACE OF THE WING.
PRINCIPLES OF FLIGHT
LIFT FORCES ON A TYPICAL WING IN FLIGHT
ONCOMING AIR
THE LENGTH OF THE ARROW INDICATES THE
AMOUNT OF LIFT BEING PRODUCED.
MOST LIFT IS PRODUCED ABOUT 1/3 FROM
THE LEADING EDGE OF THE WING.
PRINCIPLES OF FLIGHT
RATHER THAN WORK WITH LOTS OF SMALL
FORCES, THE TOTAL LIFT ON A WING IS
DEEMED TO WORK THROUGH A SINGLE POINT.
THIS POINT IS CALLED :-
THE CENTRE OF PRESURE
PRINCIPLES OF FLIGHT
DEFINITIONS
CHORD LINE IS A LINE JOINING THE LEADING
EDGE TO THE TRAILING EDGE OF THE WING.
CHORD LINE
ONCOMING AIRFLOW
THE MEAN CAMBER LINE IS A LINE EQUI-DISTANT
FROM THE TOP AND BOTTOM OF THE WING.
MEAN CAMBER
LINE
ONCOMING AIRFLOW
PRINCIPLES OF FLIGHT
SEVERAL FACTORS AFFECT THE AMOUNT OF
LIFT PRODUCED BY A WING.
AIRSPEED.
INCREASE IN AIRSPEED WILL
CAUSE AN INCREASE IN LIFT.
LIFT INCREASES BY THE SQAURE
OF THE SPEED.
2 x SPEED = 4 x LIFT
3 X SPEED = 9 x LIFT
PRINCIPLES OF FLIGHT
ANGLE OF ATTACK
CHORD LINE
ANGLE OF ATTACK
ONCOMING AIRFLOW
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 LESS
DENSE, THE LIFT WILL DECREASE.
i.e. INCREASE IN ALTITUDE.
PRINCIPLES OF FLIGHT
PRESSURE ENVELOPE AT O°
TOTAL REACTION
EQUALS LIFT
+
_
0°
LIFT = A LITTLE
+
PRINCIPLES OF FLIGHT
PRESSURE ENVELOPE AT 5°
TOTAL REACTION
_
LIFT
+
5°
DRAG
-
LIFT = MORE
+
PRINCIPLES OF FLIGHT
PRESSURE ENVELOPE AT 1O°
LIFT
_
TOTAL REACTION
DRAG
+
10°
LIFT =
MORE
+
PRINCIPLES OF FLIGHT
PRESSURE ENVELOPE AT 15°
LIFT
__
TOTAL REACTION
DRAG
15°
+
LIFT =
MORE
+
PRINCIPLES OF FLIGHT
WING SHAPE AND AREA
THE SHAPE AND WING SIZE (AREA) WILL
AFFECT THE AMOUNT OF LIFT. THESE ARE
DECIDED 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 WING
INCREASES, 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