1. Lesson 2-2a Principles of Flight

2. The Forces of Flight

3. How many forces are present when an aircraft is cruising at constant speed and altitude? a. 0 b. 2 c. 4 d. 6
Chapter 1, Lesson 2

4. Lift
Lift is produced almost entirely by moving air over and under the wings
The profile of a wing is called an airfoil
Changing the airflow on the surface of the airfoil (or wing) will increase or decrease the amount of lift

5. Bernoulli’s Principle
Faster airflow causes a decrease in air pressure
Air flowing over the curved upper surface of a wing speeds up
Increase in speed reduces pressure above the wing and produces the upward lifting force

6. Airfoils Can be wings or propeller blades
Parts of airfoil Include leading and trailing edges, camber and chord line

7. Wind Tunnels, cont.
The Wright Brothers tested more than 200 wing shapes in a tunnel before the successful glider
Researchers can carefully control airflow conditions and measure the forces on an aircraft model

8. Activity Bernoulli’s Principle in Action
Let’s do a quick experiment to demonstrate Bernoulli’s Principle in action using a funnel and a ping-pong ball

9. Effect of Angle of Attack on Flight
If a plane alters pitch—the up and down movement of the plane’s nose—the angle of attack on its wings will change
As angle of attack increases, wings generate more lifting force

10. Critical Angle of Attack
Point at which a plane stalls—around 15⁰
Chapter 1, Lesson 1
Reproduced from NASA/Glenn Research Center

11. How Lift is Generated
Air flows over top of wing reducing pressure on top surface relative to bottom surface of wing
Lift depends on aircraft’s shape, size, and velocity
To increase lift:
Increase aircraft’s forward speed
Increase airfoil’s angle of attack (up to stall angle)
Increase surface area of airfoil
Chapter 1, Lesson 2
Reproduced from NASA/Glenn Research Center

12. Airfoil Camber The curve in an airfoil is the camber
In most airfoils the upper surface curves more than the lower surface
Airfoil’s thickness is the maximum distance between the upper and lower wing surfaces

13. Airfoil Types, Purpose, and Function
Aircraft weight, speed, and purpose determine wing’s shape
Streamlined airfoils don’t create enough lift
Teardrop shaped airfoils have no lift at zero angle of attack

14. Airfoil Types, Purpose, and Function
See handout of conventional airfoils

15. The Fuselage The fuselage is the aircraft body
Fuselage vary in shape to fit the mission
Fuselage must be strong enough to withstand torque
Chapter 1, Lesson 3
Courtesy of USAF/CMSgt Gary Emery

16. Wing Position and Parts
Wing position depends on aircraft’s mission
Main internal parts are spars, ribs and stringers
Fuel tanks usually part of wing
Chapter 1, Lesson 3
Reproduced from US Department of Transportation/Federal Aviation Administration

17. Wing Angles
Dihedral angles give aircraft roll stability and level flight
Large commercial airliner wings have dihedral angles
Fighter aircraft have anhedral angles
Chapter 1, Lesson 3
Modified from NASA/Glenn Research Center

18. The Role of Stabilizers and Rudders
Stabilizers are on the aircraft’s tail
Stabilizers keep aircraft stable so it can maintain straight flight path
Vertical stabilizer prevents the nose of plane from roving side to size
Horizontal stabilizer keeps plane from bobbing up and down

19. The Role of Stabilizers and Rudders, cont.
Rudder is the hinged piece on the vertical stabilizer
Lets pilot steer the aircraft by moving the tail left or right
Elevators are the hinged flaps on the horizontal stabilizer
Lets pilot steer the aircraft by moving the tail up or down

20. The Positions of Flaps, Spoilers, and Slats on Aircraft
Flaps are hinged device at wing’s trailing edge that produces lift
Spoiler is small, flat plate that attaches the tops of wings; it increases drag
Slat is moveable, hinged parts that pivot down to generate more force

21. Primary and Secondary Controls
Primary Controls make aircraft controllable and safe to fly
Rudders, elevators, and ailerons
Secondary controls let the pilot maintain more control over aircraft’s performance
Flaps, slats, and spoilers

22. Primary Flight Controls
Pilot uses primary flight controls to control aircraft yaw, pitch, and roll
Rudders control yaw or side-to-side motion of aircraft
Elevators control pitch or up and down motion of aircraft
Ailerons control roll or banking of the wings

23. How Ailerons Work
Aileron is a small hinged section on the outboard portion of each wing
Ailerons operate in opposite direction on the wings, causing one to increase lift (point aileron down), one to decrease lift (point aileron up)

24. Secondary Flight Controls
Used primarily in more challenging flight conditions where low speeds are required (take-off and landing)
Flaps are on trailing edge of wings and increase/decrease lift and drag on both wings at the same time
Slats are on the leading edge of the wings and also increase/decrease lift and drag on both wings at the same time
Spoilers reduce lift and increase drag and can be used on both wings at same time or on one wing and not the other

25. Spoilers
Spoilers are small, flat plates that attach to the tops of the wings with hinges
Raising spoilers on both wings slows aircraft in any phase of flight
Raising spoilers on only one wing causes a rolling motion

26. Activity: Airplane Parts and Functions
Label the airplane parts
Define their function in flight