The Physics of Flight

1. The Physics of Flight

2. Ancient Dreamers • Legends of flight attempts date to 2000 B.C. • Many believed flying was for the mythical gods • Others tried to copy bird flight-unsuccessfully • Chinese invented kites about 1000 B.C. • 17th century A.D. kites carried soldiers aloft • Leonardo da Vinci, 15th century Italian artist • First recorded scientific study of aeronautics • Experimented to prove feasibility of mechanical flight • Drew sketches and plans to construct flying machines

3. Ancient Dreamers • Leonardo da Vinci • Daedalis & Icarus Italian artist and scientist Leonardo da Vinci (1452-1519) gathered data on the flight of birds and developed concepts of the propeller, the parachute, and heavier-than-air craft.

4. The Quest for Flight • By 17th Century, ancient ideas inspired scientific theories and experiments • Characteristics of the atmosphere and the discovery of gasses and properties led to lighter-than-air balloon experiments • Airships needed power and direction control • Glider flying increased the understanding of flight forces, wing geometry & controls

5. Definition: Aerodynamics Aerodynamics is a branch of fluid mechanics that deals with the motion of air and other gaseous fluids, and with the forces acting on bodies in motion relative to such fluids

6. Bernoulli’s Principle • According to Bernoulli’s Principle, as the velocity of a fluid increases the pressure exerted by the fluid decreases.

7. Air Flow Past a Wing • The air speed is greater over the upper surface, as indicated by the closer streamlines, the air pressure is lower there and the wing is lifted • When the wing is angled upward, air deflected from its lower surface provides additional lift. • If the angle is too great, turbulence reduces lift and increases drag.

8. Powered Flight Breakthrough • Experiments showed basic ingredients of flight are: sufficient power, lift , control • Wright’s successfully applied theories of lift and drag to practical use in powered gliders • Progress (and a conventional designs) came with lighter materials and drag reduction

9. Breakthrough The Main Events • Sir Hiram Maxim • power, lift, control • Wright brothers • Glen Curtiss • Improved designs, promoted aviation December 17, 1903, near Kitty Hawk, North Carolina, Wilbur and Orville Wright made the world's first successful powered, free, controlled, sustained flights in a heavier-than-air craft.

10. World War I • War speeds up technology development • Airplane speed, loads increased • Large manufacturing base developed The Main Events Congressional medal of Honor winner Captain Eddie Rickenbacker went on to be a pioneer in civil aviation, too

11. After the War • Veteran pilots kept interest alive • Commercial aviation catches on • Dramatic design advances • Beginning of rocket flight • Invention of the jet engine

12. Four Forces of Flight • Lift • Weight • Thrust • Drag Source: NASA Glen Research Center

13. Forces on an Airplane

14. Lift • Lift is an aerodynamic force • Lift must exceed weight for flight • Generated by motion of aircraft through air • Created by the effects of airflow past wing • The top of an airplane wing is curved, so that air has to travel further to reach the trailing end of the wing. • Therefore, the air on the underside of the plane is exerting more pressure, causing the plane to lift.

15. Weight • Weight is not constant • varies with passengers, cargo, fuel load • decreases as fuel is consumed or payload off-loaded • Direction is constant toward earth’s center • May be assumed concentrated at the center of gravity

16. Drag • An aerodynamic force • Drag is also called air resistance. • the force that pulls the plane backward. • Two broad drag classifications • Parasite drag: drag created by airplane design • Induced drag: by-product of lift generation • Acts through the center of pressure

17. Thrust • Forward-acting force opposes drag • Direction of thrust depends on design • Propulsion systems produce thrust • Equal to drag in straight, constant speed flight

18. Stability • Center of Gravity • Center of Pressure • Longitudinal Stability • Lateral Stability • Directional Stability

19. Definition: Aeronautics • Aeronautics is the design and construction of aircraft and • The theory and practice of aircraft navigation

20. Definition: Aerospace Engineering • Aerospace engineering is closely allied to aeronautics and aeronautical engineering but • Includes the study and development of rocket engines, satellites, and spacecraft

21. Activities and Exercises • Build gliders for flight control experiments • Worksheets