How Do Airplanes Fly Upside Down if It’s the Shape of the Wings That Make Them Fly?

Introduction to Airplane Flight Mechanics

The question of how airplanes can fly upside down, despite the commonly held belief that wing shape is paramount to flight, invites a deeper exploration into the physics of aerodynamics. The key factor that allows planes to maintain lift, even when inverted, is not the shape of the wings but rather the concept known as the angle of attack.

The Role of Angle of Attack

The angle of attack is defined as the angle between the chord line of the wing (an imaginary line from the leading edge to the trailing edge) and the direction of the incoming air. This angle plays a crucial role in generating lift. According to the principles laid out in “Flight Physics” by Egbert Torenbeek and H. Wittenberg, and detailed by NASA’s educational resources, the lift produced by a wing primarily stems from its angle of attack rather than its shape.

When a wing is tilted with the leading edge up relative to the oncoming airflow, it causes the air pressure beneath the wing to increase while the pressure above it decreases. This pressure difference effectively creates lift.

Wing Shape vs. Angle of Attack

While it is true that a wing with a curved upper surface (airfoil) can lead to a decrease in pressure above the wing, this effect is secondary to the primary mechanism of lift generation, which is the angle of attack. Even a perfectly flat wing can generate lift if it is tilted appropriately.

To illustrate, you could theoretically achieve lift with an object as simple as a brick, provided it is positioned correctly and has sufficient thrust from a powerful motor. This demonstrates that the ability to fly is not solely reliant on wing shape but rather on how the wing interacts with the airflow.

Stunt Planes and Symmetrical Wings

In the case of stunt planes specifically designed for aerobatics, these aircraft often utilize symmetrical wings. These wings are engineered to produce lift regardless of their orientation. When such planes fly upside down, they simply adjust their angle of attack to maintain lift.

This ability to manipulate the angle of attack allows pilots to perform complex maneuvers, including inverted flight, without relying on the traditional airfoil shape that is typically associated with conventional flight.

Conclusion

In summary, the assertion that the shape of the wings is the primary determinant of an airplane’s ability to fly is a simplification. The angle of attack is the critical factor that enables flight, allowing aircraft, including those designed for stunts, to fly upside down by tilting their wings in the correct direction. This understanding not only demystifies the mechanics of flight but also highlights the remarkable adaptability of aerodynamic principles in various flight scenarios.