Four Forces of Flight

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

2. Forces on an Airplane

3. 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 • Aircraft lift acts through a single point called the center of pressure.

4. 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

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

6. Drag • An aerodynamic force • Resists forward motion • Two broad drag classifications • Parasite drag: drag created by airplane design • Induced drag: by-product of lift generation • Acts through the center of pressure

7. What’s Missing?

9. Control & Propulsion

10. Scientific Method

12. Think about what the world still needed before controlled flight could become a reality