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THEORY OF FLIGHT 1 PO 402 CI Norwood References: FTGU Pages 9-50, Pilot’s Handbook of Aeronautical Knowledge Chapters 1-3.

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Presentation on theme: "THEORY OF FLIGHT 1 PO 402 CI Norwood References: FTGU Pages 9-50, Pilot’s Handbook of Aeronautical Knowledge Chapters 1-3."— Presentation transcript:


2 THEORY OF FLIGHT 1 PO 402 CI Norwood References: FTGU Pages 9-50, Pilot’s Handbook of Aeronautical Knowledge Chapters 1-3

3 Review from last class 1. What is the VFR weather minima for fixed wing aircraft <1000’ AGL in uncontrolled airspace? 2. You are on final approach and you receive a flashing red light from the tower. What does it mean and what do you do?

4 Topics to be covered today  The fuselage and empennage  Parts of the airplane  Four forces acting on an aircraft  How lift is created  Boundary layer

5 What is an airplane?  The Canadian Air Regulations defines an airplane as:  “A power driven, heavier-than-air aircraft, deriving its lift in flight from aerodynamic reactions on surfaces that remain fixed under given conditions of flight”

6 Definitions  Aircraft: any machine capable of deriving support in the atmosphere from the reactions of the air  Glider: heavier-than-air aircraft not equipped with a motor, which derives its lift from aerodynamic reactions on surfaces which remain fixed under given conditions of flight  Airframe: Total structure of the aircraft including fuel systems and fuel tanks but excluding instrumentation and engines

7 Classification  Aircraft can be classified according to:  Position and number of wings  The number of engines  configuration of the undercarriage

8 Parts of the Airplane

9 Fuselage  The fuselage is the main body of the aircraft  Holds all passengers and cargo  Almost all parts of the aircraft are attached to the fuselage  Three types of fuselage construction: Truss type Monocoque Semi-monocoque

10 Truss Type (SGS 2-33A)  Steel or aluminum tubing (wood in antique aircraft)  Strength is achieved by welding tubes into triangles called “trusses”  Longerons make up the frame which are supported by diagonal and vertical members

11 Monocoque (Katana)  Uses a stressed skin to handle all loads  Main construction consists of formers to give shape and bulkheads to seal off and connect sections  Very strong but heavy due to the strength requirement of the skin

12 Semi-Monocoque (Airbus 320)  Structure of formers, bulkheads and stringers to create a frame  Frame is covered by a stressed skin to take some of the bending stresses  Most common type of fuselage construction

13 Review 1. What is an aeroplane according to the CARs? 2. What are the main parts of an airplane? 3. What are the three types of fuselage construction?

14 Empennage  Horizontal stabilizer – Non movable horizontal surface  Elevator – Movable surface attached to the horizontal surface  Fin or Vertical stabilizer – Non movable vertical surface  Rudder – Movable surface attached to vertical stabilizer

15 Canard  In some aircraft, the horizontal tail is moved forward  Seen in early aircraft such as the Wright Flyer and modern aircraft such as the Beech Starship and fighter aircraft Canard

16 Stabilator  One piece movable surface that replaces the elevator and horizontal stabilizer  Stabilators have a movable surface called an anti-servo tab which act as trim tab to relieve control surfaces

17 The Wings and Lifting Surfaces  Two main types of wing configuration  Monoplane – One wing  Biplane – Two wing

18 Wing Positioning  Three positions for the wing relative to the fuselage:  High-wing – Attached on top  Mid-wing – Attached in the middle  Low-wing – Attached on the bottom

19 Review 1. What surfaces make up the empennage? 2. What is a stabilator? 3. What are the three types of wing positioning?

20 Construction of the Wing  Spar – Run from wing root to tip, stiffens the wing  Ribs – Run from leading edge to trailing edge and give wing its shape  Compression struts – Tubes placed between spars to handle compression loads

21 Construction of the Wing  Drag and anti-drag wires – Resists bending forces from the wing going through the air  Ailerons – Movable surface on the outboard sections that control roll. Move in opposite directions on each wing

22 Construction of the Wing  Flap – Movable section next to the wing root  Wingspan – Distance from wingtip to wingtip

23 Construction of the Wing  Chord – Imaginary straight line from the leading edge to the trailing edge  Struts – External bracing that support the wings, mainly seen in high wing aircraft Struts

24 Review 1. What are the main components of the wing? 2. What do ailerons do? 3. What is the chord?

25 Landing Gear  Absorbs shock of landing  Allows the movement of the aircraft on the ground  Can be either fixed or retractable

26 Type of Landing Gear Conventional (Tail dragger)Tricycle (Nose wheel) Mono-wheel

27 Conventional Gear  Less parasite drag  Cheaper  Better ground handling  Better handling on rough strips  More difficult to land  Has tendency to nose- over  Poor ground visibility  Poor crosswind handling AdvantagesDisadvantages

28 Tricycle Gear  Easy to land  Good ground visibility  Good crosswind handling  Very small chance of ground looping  More parasite drag  Poor ground clearance for propeller  Poor performance on rough surfaces AdvantagesDisadvantages

29 Propulsion System  For smaller GA aircraft the main parts of the propulsion system are:  Engine: Provides rotation for the propeller  Propeller: Creates thrust through rotation  Cowling: Covers the engine and provides cooling through air ducts

30 Review 1. What are the two types of landing gear? 2. What are some advantages/disadvantages of those landing gear? 3. What are the main components of the propulsion system?

31 The Four Forces

32 Lift  Lift opposes weight through aerodynamic reactions  Creation of lift can be explained through two separate principles:  Newton’s Three Laws of Motion  Bernoulli’s Principle

33 Newton’s Three Laws of Motion  1 st law: An object in motion will stay in motion and an object at rest will stay at rest unless acted on by another force  2 nd law: Acceleration of an object is inversely proportional to the mass of the object and proportional to the force applied (ex. You trying to push a school bus as opposed to a soccer ball)  3 rd law: Every action has an equal and opposite reaction

34 Bernoulli’s Principle  Energy in a system must remain constant  If we look at a venturi tube, the amount of air entering in the tube must equal the air exiting the tube (flow rate)

35 Bernoulli’s Principle  As the tube decreases in size the velocity of the air must increase to maintain the same flow rate, therefore kinetic energy increases  This causes the pressure to drop and the energy remains constant

36 How lift is actually created  As the air flows over the wing, it accelerates as it moves over the cambered surface (just like in a venturi tube)  This causes the pressure above the wing to decrease, creating a force that sucks the wing into the air

37 How lift is actually created  On the underside of the wing, the air is deflected downwards which pushes up on the wing  Also, air flowing off the top of the wing is deflected downwards, this contributes to lift  This phenomenon is called downwash and is a result of Newton’s 3 rd law Force acting on air Force acting on wing DOWNWASH

38 Review 1. What is Bernoulli’s Principle? 2. What are Newton’s three laws of motion? 3. How does a wing create lift?

39 Weight  Weight is the downward force created on the aircraft due to gravity  All of the weight acts through a single point called the centre of gravity

40 Thrust  Thrust is force that moves the aircraft forward through the air  While there are many ways of producing thrust, all rely on the principle of moving air backwards to create a reaction to push the aircraft forward

41 Drag  Resistance to the motion of the aircraft through the air  There are two main types of drag:  Parasite drag – Created by parts of the aircraft that do not contribute to lift  Induced drag – Created by parts of the aircraft that contribute to lift

42 Parasite drag  Form Drag: Drag created by the shape of the aircraft. Can be reduced through streamlining  Skin friction: Drag created by the roughness of the skin, can be made worse through dirt and ice accumulation  Interference drag: Drag created by two parts of the aircraft that create eddies where they intersect (such as the struts and wings)  Parasite drag increases as speed increases

43 Induced drag  Created by parts of the plane that create lift  Cannot be completely eliminated  Greater the lift, greater the induced drag  Reduces as speed increases

44 Review 1. What do we call the point at which all weight acts through? 2. How is thrust generally produced? 3. What are the two types of drag?

45 Airfoils  An airfoil is any surface designed to create lift  Most suitable surface for creating lift is a curved or cambered surface

46 Camber  Camber is the curvature of the upper and lower surfaces of the wing  Usually the upper surface is more curved that the lower surface

47 Equilibrium  When two forces are equal and opposite, they are said to be in equilibrium  When the forces are equal, the aircraft will continue to move at a constant rate of speed

48 Couples  When two forces are opposite and parallel, but not acting through the same point, a couple is created  This couple will cause rotation about a given axis  An example of this would be drag acting opposite and parallel above thrust, this would cause the nose of the aircraft to rise

49 Relative Airflow (Relative Wind)  Direction of the airflow with respect to the wing  Created by the motion of the aircraft through the air  Can also be created by air moving around a stationary object  When an aircraft is on the take-off roll, the aircraft will be subjected to the relative wind by it’s own motion through the air and by the wind

50 Review 1. What is camber? 2. What is equilibrium and when would an aircraft be in equilibrium? 3. What is a couple and what can it do to an aircraft? 4. What is relative airflow?

51 Aileron Drag  When an aircraft banks to turn, one ailerons moves up, the other one goes down  The down going aileron compresses the air underneath the wing and creates more lift, rolling the aircraft  By creating more lift, more drag is created and the aircraft yaws opposite turn  This is called adverse yaw

52 Aileron Designs Differential AileronsFrise Ailerons

53 Secondary Effects of Controls  Yawing moment in the direction of the turn created by the relative airflow hitting the side of the fuselage ahead of the c of g  Rolling moment in the direction of the turn due to the outside wing moving faster through the air creating more lift AileronsRudder

54 Lift and Drag Curves  Lift and drag are dependant on several factors:  Angle of attack and the shape of the airfoil – C L and C D  Wing area – S  The square of the velocity – v 2  Density of the air – ρ  Lift equation: L = ½ C L v 2 ρ  Drag equation: D = ½ C D v 2 ρ

55 Lift and Drag Curves

56 Center of Pressure  If we consider the pressure distribution across the wing as a single force, it will act through a straight line  This is called the centre of pressure

57 Center of Pressure  As lift increases, the center of pressure moves forward until the wing stalls  The C of P then moves backwards, this can cause the aircraft to become unstable

58 Review 1. What is aileron drag and what does it create? 2. What factors affect lift and drag? 3. What is the center of pressure and how does it move when the angle of attack is increased?

59 Boundary Layer  The boundary layer is a thin sheet of air that sticks to the wing  This occurs because air is viscous (or has a resistance to flow)  The airflow slows down as it gets closer to the surface as a result of friction between the air and the surface  If we use a wing as an example, the airflow would be smooth at the front of the wing, this is called the laminar flow region

60 Boundary Layer  As the air continues to flow back, it slows down due to friction and eventually becomes turbulent, this is called the turbulent flow region  The point at which it changes from laminar to turbulent flow is called the transition point

61 Airfoil Design - Conventional  Thick airfoil that allows for better structure and lower weight  Camber is maintain further rearward which increases lift and reduces drag  Good stall characteristics  Thickest part of the wing is at 25% of the chord

62 Airfoil Design - Laminar  Designed for faster aircraft because of the reduced drag  Thinner than the conventional airfoil and the cambering is almost symmetrical  Thickest part of the airfoil is 50% of the chord

63 Review 1. What is the boundary layer? 2. What happens to the boundary layer as air flows back over a wing? 3. What is the main difference between a conventional and laminar airfoil

64 Angle of Incidence  Angle at which the wing is permanently inclined to the horizontal axis  Most airplanes have a small angle of incidence to ensure a small angle of attack and therefore a greater visibility during cruise

65 Wash-in/Wash-out  Reduces the tendency for the entire wing to stall at the same time  The wing is slightly twisted so that the wing root is has a higher angle of incidence (hence a higher angle of attack) than the wing tip, forcing it to stall first  This allows for the pilot to have more control during a stall

66 Flaps  High lift devices attached to the trailing edge of the wing at the root  They will provide the pilot with: - Better take off performance - Steeper approach angles - Slower approach and landing speeds

67 Spoilers and Divebrakes  Spoilers and divebrakes are devices attached to the upper and lower surfaces of the wing  When extended into the airflow, they will decrease lift and increase drag  This allows for a steeper approach angle without having to increase speed

68 Spoilers and Divebrakes

69 Review 1. What is wash-in/wash-out and why would we have it on an airplane? 2. What do flaps do? 3. What do spoilers and divebrakes allow the pilot to do?

70 Wing Fences  Fins attached to the upper surface of the wing  Control the movement of air over the wing to allow for better handling at low speed and improve stall characteristics

71 Winglets  Mounted vertically on the wingtips  Small airfoil surfaces  Break up the wingtip vortices which flow towards the upper surface of the wing

72 Slats and Slots  Extra airfoil on the leading edge of the wing  When a high angle of attack is encountered, the slat moves forward to allow for more airflow and increase lift  Passageway built into the leading edge of the wing  Increases airflow over the wing at high angles of attack  Remains stationary SlatSlot

73 Slats and Slots

74 Vortex Generators  Small airfoils placed along the wing  When the air flows over them, small vortices will be created, re-energizing the flow which prevents the air from separating and becoming turbulent  This helps increase lift and decrease drag

75 Vortex Generators

76 Review 1. What are wing fences? 2. What’s the difference between a slat and a slot? 3. What do vortex generators do?

77 More review 1. What are the three types of fuselage construction? 2. What are the four forces acting on an aircraft? 3. How is lift created? 4. What is equilibrium? 5. What are flaps? 6. What do slats do?

78 Summary  Today we have covered:  Parts of the aircraft  Forces on the aircraft  How lift is created  Boundary layer  Next class we will continue theory of flight!

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