Presentation on theme: "Theory of Flight 6.05 Lift and Drag References:"— Presentation transcript:
1 Theory of Flight 6.05 Lift and Drag References: Transport Canada Study and Reference Guide Glider PilotFTGU pages 91-98
2 Review 1. Name the 4 forces acting on an aircraft. 2. What are Newton’s 3 laws?3. Is an aircraft considered to be in a state of equilibrium when it is on the ground.Answers:Lift, Weight, Thrust, Drag2. A body persists its state of rest or of uniform motion will stay in motion unless acted on by an external unbalanced force.Force = mass x accelerationFor every action, there is an equal and opposite reaction3. No
3 6.05 Lift & Drag MTPs: Bernoulli’s Principle- how lift is created Airfoil termsAngle of attack versus liftAngle of IncidenceTypes of airfoilsTypes of DragWingtip VorticesStreamlining
4 Bernoulli’s Principle An increase in the speed of a fluid occurs simultaneously with a decrease in pressure or a decrease in the fluid's potential energy.
6 Bernoulli’s Principle Airfoils are shaped in a way to manipulate air pressure based on Bernoulli’s principle.Air moves faster over the upper surface of the wing, decreasing pressure (or increasing suction)Air moves slower over the lower surface of the wing and creates a higher pressure, or pushing force.
7 Airfoil Terms Terms related to airfoils Relative Airflow Angle of AttackCentre of Pressure
8 Relative AirflowThe direction of the airflow with respect to the wing.It is created by the movement of the airplane as well as the movement of air.Relative airflow is usually opposite to the flight path.Relative airflow itself is not related to lift
9 Angle of AttackThe angle at which the airfoil meets the relative airflow
10 Centre of Pressure Is the average of the pressure on an airfoil Sum of the distributed pressures on the airfoil acting through a single straight lineMoves forward on an airfoil as the angle of attack is increased
12 A of A versus Lift Lift Increases Drag Increases Now we know how we get lift but how much can we get?One factor affecting lift is Angle of AttackAs the angle of attack increases, what happens to lift?BUT… As the angle of attack increases, what happens to drag?Lift IncreasesDrag Increases
14 Angle of IncidenceThe angle of incidence is the angle between the mean aerodynamic chord of the wing and the longitudinal axis of the aircraftThe angle of incidence impacts forward visibility, take-off and landing characteristics, and drag in level flight
15 Types of Airfoils Airfoil Airfoil – 2D vs. Wing – 3D A two-dimensional surface designed to obtain a reaction from the air through which it moves.The shape of an airfoil will affect how air flows over the wingAirfoil – 2D vs. Wing – 3D
16 Types of Airfoils What are some functions of airfoils? Create lift Create thrustAttachment point for the control surfaces (including flaps, slots, slats, etc)House fuel tanks and instrument componentsStability
18 Confirmation 1. Label where the high pressure and low pressure are: 2. Fill in the blanks__________________: The angle at which the airfoil meets the relative airflow__________________: airflow with respect to the wing__________________:the average of the pressure on an airfoil
19 Confirmation 3. Lift acts 90o to the ________________. 4. Bernoulli’s principle states that:An ____________ (increase/decrease) in the speed of a fluid occurs simultaneously with a _____________________ (increase/decrease) in pressure or a _______________ (increase/decrease) in the fluid's potential energy5. As lift increases, drag _______________.
20 DragIs the resistance an airplane experiences in moving forward through the air
21 Types of Drag There are 2 main types of Drag: Parasite Drag– This drag is further broken downForm dragSkin Friction2. Induced Drag
22 Parasite DragDrag of all those parts the airplane which DO NOT contribute to liftThis drag is hard to eliminate but it can be minimizedForm drag is caused by the shape of the aircraftLanding gearAntennasStrutsWing tip fuel tanks
23 Parasite Drag Skin Friction The tendency of air flowing over the body to cling to its surfaceWhat causes it to resist motion?Ice on the wingsDirt build up
24 Induced DragCaused by those parts of an airplane which are active in producing liftCannot be eliminatedLift Drag
25 Induced DragInduced drag can be reduced with a high aspect ratio
26 Due to the pressure changes Wing Tip VorticesOver the top of the wing the airflow goes inwardUnder the bottom of the wing the airflow moves outwardDue to the pressure changesThis creates a swirling motion off the wing tip called a vortex
27 Streamlining The less drag you have… Flying a glider: the further you can flyFlying an airplane: the less fuel you useTherefore streamlining is importantA design device by which a body is shaped to minimize drag
28 Confirmation Fill in the diagram Is it possible to eliminate induced drag? Why or why not?