INTRODUCTORY: AERODYNAMICS

Discuss Bernoulli’s principle early in the session, and pass out the Angles of Attack activity sheet. Explain why an airfoil creates lift. A good demonstration of lift is to cut a half-inch strip from a piece of 8.5-by-11-inch paper. Hold the paper to your chin, hanging down, and ask participants to predict what will happen when you blow. Did they expect the paper to rise toward the blown breath?

Starting at the propeller, point out that an aircraft has many airfoils on it. Say: One of them you’re staring at, and it’s not a wing. What is it? Point out the propeller and how it is shaped like an airfoil, and explain how it produces thrust. Ask: If the prop always spins in a clockwise direction, why does the plane want to turn left? (Imagine the prop on the end of a boat. Spinning it makes the boat want to move toward the right. Because the prop on a plane is in front, not in back, it wants to go toward the left.)

Working from the front of the plane to the back, point out all airfoils and controls. Point out and discuss the propeller, wing, stabilizer, elevator, and trim tab.

Discuss stalls. Ask: What causes the plane to not fly? (The interruption of the airflow over the wing. Flat on bottom and curved on top is important. Changing the shape of the airfoil for any reason—including icing—changes the plane.)

Pass out the Aerodynamic Forces in Flight activity sheet, and discuss how the four forces (lift, weight/gravity, thrust, and drag) act in flight.

Discuss the following:

• Slipstream, airflow over a wing, angle of attack, and turbulence.
• How the power setting affects the airplane’s attitude and how it is used to aid flight.
• How to make sure everything is configured for takeoff.
• With their arms out at their sides, have participants simulate, using their hands at different angles, what happens to the ailerons in a right-hand turn and a left-hand turn.
• The turn coordinator and the bank and slip indicator on the instrument panel. Demonstrate how the ailerons and rudder are used in coordination to turn the plane. Explain why slips and skids are bad, and how stalls during uncoordinated flight can lead to spins.
• Aerodynamic differences between a level turn and a climbing turn, and the tendency to lose altitude in a turn and why.
• Weight, balance, and the center of gravity and how these are planned for before a flight begins. This is part of the preflight and must include baggage, weights of all passengers, and any cargo. Discuss the calculations, why this is such an important part of flight planning, and why having too much overall weight is bad. Questions like “What happens when too much weight is forward or backward?” can help prompt participation.

Describe density altitude, explaining that hot weather and humid skies rob the airplane of lift and thrust. Use Aspen, Colorado, as an example. Density altitude is not a huge issue in flat Midwestern cities but can be a very big issue elsewhere.

Have students complete the Aerodynamics Wrap-Up activity sheet and answer any questions they may have.

TIPS AND OPTIONS

• Close the airplane doors and take off the control lock. When using the yoke and rudder pedals to control the wing and tail surfaces, participants may get distracted. Stay outside and manipulate the controls by moving them manually from the outside.
• If possible, have someone in the cockpit work the ailerons while the group watches them go up and down.
• If possible, have someone in the cockpit work the rudder to demonstrate what happens when the right or left foot pedal is pressed.
• If there is time and the group is small and well-behaved, let participants take turns sitting in the cockpit. Let them manipulate the yoke and rudders.
• Because girls tend to be more hesitant to participate in these activities than boys, try to engage the girls by asking questions, letting them manipulate the plane’s surfaces, and having them use their arms to simulate wing activity.