How an Airplane Creates Lift | Complete PPL Ground Course (Lesson 2)

Summary

In this second private pilot ground lesson, Josh and Mike explain how an airplane generates lift. They discuss key aerodynamic principles, including Bernoulli's Principle, which explains how faster airflow over a wing's curved surface creates lower pressure, leading to lift. They also cover the effects of airspeed, wing shape (camber), angle of attack, and Newton's Third Law on lift production. Using real-world flying examples, they demonstrate how increasing airspeed, lowering flaps, or adjusting the plane’s angle of attack can increase lift but also increase drag. The lesson provides foundational knowledge for aspiring pilots.

Takeaways

• ✈️ Lift is an essential force for flight and opposes the weight of an aircraft.
• 🛫 Wings create lift using two main factors: relative wind and wing shape.
• 🧑‍🏫 Lift is defined as an upward force and, in steady unaccelerated flight, lift equals weight.
• 🌀 Bernoulli's principle explains that as the velocity of air increases, pressure decreases, contributing to lift.
• 🌬️ The curved surface of a wing (airfoil) causes air to move faster on top, creating lower pressure and higher pressure below, generating lift.
• 💨 Increasing airspeed, lowering flaps, or raising the angle of attack can increase lift but also increase drag.
• 🔄 Changing the camber (curvature) of a wing, often by lowering flaps, increases lift by making the air on top travel a farther distance.
• 📉 Newton's third law contributes to lift when air strikes the lower surface of the wing, pushing it upward.
• ⚖️ Increased lift can be achieved by increasing thrust or changing wing shape but always comes with a trade-off of increased drag.
• 🚀 Understanding these aerodynamic principles helps control the aircraft more effectively during flight.

Q & A

What is lift, and why is it important for flying?

Lift is an upward force that opposes the weight of an aircraft and everything on board. It is essential for flying because it allows the aircraft to stay in the air.

What two key factors help wings create lift?

Wings create lift using two key factors: relative wind and the shape of the wing.

How does Bernoulli's principle explain the creation of lift?

Bernoulli's principle states that as the velocity of a moving fluid increases, the pressure within that fluid decreases. On an airplane wing, the air traveling over the curved upper surface moves faster, creating lower pressure above the wing, while the slower-moving air below the wing creates higher pressure, generating lift.

What role does the relative wind play in lift creation?

Relative wind, which is the combination of wind caused by the aircraft's thrust, prop wash, and natural wind conditions, interacts with the wings. The faster the relative wind, the more lift is produced.

Why do airplanes take off and land into the wind?

Airplanes take off and land into the wind because it provides more relative wind, helping to generate more lift for safer and more efficient takeoffs and landings.

What is the camber of the wing, and how does it affect lift?

The camber is the curvature of the wing. Increasing the camber makes the air travel farther over the top of the wing, increasing lift, but it also increases drag.

How do flaps help increase lift?

Lowering the flaps increases the camber of the wing, which increases lift. However, it also increases drag, reducing airspeed.

What is the angle of attack, and how does it influence lift and drag?

The angle of attack is the angle between the wing and the relative wind. Increasing the angle of attack increases lift by exposing more surface area of the wing to the wind, but it also increases drag.

How does Newton's third law apply to lift generation?

Newton's third law states that for every action, there is an equal and opposite reaction. When relative wind strikes the lower surface of the wing, it pushes the wing up, contributing to lift.

What happens to lift when airspeed is increased?

When airspeed increases, the relative wind over the wings increases, resulting in more lift. For example, increasing thrust can increase airspeed and cause the aircraft to climb.