Airfoils, Lift and Bernoulli’s Principle

1. Airfoils, Lift andBernoulli’s Principle

2. History • Ancient Discoveries • Chinese and kites • Early flight explorers Lilienthal and Cayley in the 1800s • Camber • A measure of the curvature of the airfoil • Airfoil • a part with a flat or curved surface, such as a wing or rudder, specifically designed to keep an aircraft in the air.

3. Airfoil

4. Airfoil Trailing Edge Leading Edge Angle of Attack

5. Bernoulli’s Principle The pressure of a fluid decreases as the speed of the fluid increases • The principle was first discovered in the 1700s. • When a fluid moves quickly, its pressure decreases. • Since air is considered a fluid, this principle can be applied to the design of a wing.

6. Lift Bernoulli’s Principle • When a fluid moves fast, its pressure decreases. • Since air is considered a fluid, this principle can be applied to the design of a wing.

7. Bernoulli’s Principle • Both streams must meet at the end of the wing at the same time. • Stream A has farther to go; therefore, it must travel faster.

8. Bernoulli’s Principle • Bernoulli proved that as fluids move faster, their pressure decreases. • This principle explains why a plane rises.

9. Factors that Affect Lift The Object: Shape and Size The Motion: Velocity and Angle of Attack The Air: Mass, Viscosity, Compressibility

10. Factors that Affect Lift The Object – Wing geometry • Airfoil shape • Wing size • Aspect ratio: Mathematical relationship between the wing span (overall length) to the wing area

11. Factors that Affect Lift Motion – Move the object • Velocity (speed) • Angle of attack (how the object is tipped toward the wind)

12. Factors that Affect Lift Air – Mass • Viscosity • Stickiness • Compressibility • Springiness • Density Altitude • Density of air molecules at a given altitude

13. Airfoil Shapes and Lift Wing or Airfoil? • Airfoil is a shape designed to generate as much lift as possible while incurring as little drag as possible. • The wing is attached to a plane and must take into consideration drag and the lift created.

14. Angles and Airfoils Angle of Incidence • The tilt of the wing with respect to its attachment to the body of the airplane (fuselage)

15. Angles and Airfoils Angle of Attack • The tilt of the airfoil with respect to the airflow

16. Angles and Airfoils Tilt with respect to airflow Airflow must remain smooth • Small angle of attack; air flows smooth on the surface

17. Angles and Airfoils Angle of attack becomes too steep • Airflow is disrupted and the airplane loses lift or stalls • Critical Angle of Attack is the point where it stalls

18. Angles and Airfoils Causes of stall • Flying at too steep an angle • Real-life flying situations • Sudden gust of wind decreases the plane’s forward speed, decreasing the airflow over the wing • Flying too slow (indicated airspeed) • Wing icing • Changes the shape of the airfoil

19. Amount of Lift Amount of lift produced by an airfoil depends on may factors • Angle of attack • Lift devices used (flaps, etc.) • Density of the air • Area of the wing • Shape of the wing • Speed at which the wing is traveling

20. Now follow along as we prove Bernoulli’s Principle is True!

21. Image Resources Aerospaceweb.org. (2009). Ask-Us – Parts of an airplane. Retrieved June 26, 2009, from http://www.aerospaceweb.org/question/design/q0101.shtml Microsoft, Inc. (2008). Clip art. Retrieved June 26, 2009, from http://office.microsoft.com/en-us/clipart/default.aspx National Aeronautics and Space Administration (NASA). (n.d.). Virtual skies: Aeronautics tutorial. Retrieved June 24, 2009, from http://virtualskies.arc.nasa.gov/aeronautics/tutorial/intro.html National Aeronautics and Space Administration (NASA). (n.d.). FoilSimU beta version 1.5a. Retrieved June 19, 2009, from http://www.lerc.nasa.gov/WWW/K-12/aerosim/applet/vj402.html