2 The Airfoil Airfoil Characteristics TopLeading edgeTrailing edgeBottomAirfoil CharacteristicsRounded Leading Edge – to split the airSharp Trailing Edge – to reduce turbulenceFlat BottomDeclining Top
3 Air Flow Air flow is caused by both: 1. the motion of the wing moving forward and2. natural windThe air is split in half where it meets the leading edgeThe air recombines at the trailing edgeAir on top of the airfoil moves faster than air on the bottom , but why?
4 Venturi Effect As a fluid (air) is compressed it moves faster The effect of compressing fluidsAs a fluid (air) is compressed it moves faster
6 Half a Venturi So the air on top of the air foil moves FASTER The asymetric shape of the air foil causes the air on top to be compressed while the air on the bottom is hardly moved
7 Why is this important?Bernoulli’s Principle: The pressure air exerts as it moves decreases as the speed of the air increases
8 The faster I make my airfoil go, the more I decrease the air pressure on top of my airfoil
9 Lift How does this help? Pressure on top and bottom are equal Aircraft on the groundPressure on top is less than pressure on bottomAircraft moving forwardLift
10 Which parts does the pilot control??? Calculating LiftL = (1/2) d v2 s CLL = Lift, which must equal the airplane's weight in poundsd = density of the air. This will change due to altitude. These values can be found in a I.C.A.O. Standard Atmosphere Table.v = velocity of an aircraft expressed in feet per seconds = the wing area of an aircraft in square feetCL = Coefficient of lift , which is determined by the type of airfoil and angle of attack.Which parts does the pilot control???Velocity (speed) and Density (altitude)
11 How can I use this when flying? Imagine you are flying and you are having trouble keeping the aircraft from losing altitude.What should you do?
12 Things to know Lift is always perpendicular to the wing (airfoil) Ground
13 Things to knowLift must equal aircraft total weight for aircraft to fly levelWeight exceeds Lift will cause aircraft to descendLift exceeds weight will cause aircraft to climb
14 ExploreIf you were an aircraft designer how would you design an airfoil for:A passenger airlinerA fighter
15 What is the Venturi effect? Memory CheckWhat is the Venturi effect?
16 Where does the Venturi effect occur on the Airfoil? Memory CheckWhere does the Venturi effect occur on the Airfoil?
17 Memory CheckDescribe the sequence of events that leads to lift using a thinking map
18 How lift is created Bernoulli Venturi Aircraft moves forward Air moves around wingAir on top compressesAir on top moves fasterAir pressure on top decreasesPressure differences create lift