The commonly taught explanation (for people from my generation) for how airplanes generate lift often relies on the Bernoulli Principle, which states that faster airflow over the curved top of a wing reduces pressure, creating lift. However, this explanation oversimplifies the complex physics involved and is labelled an inaccurate theory by NASA. The true mechanism behind lift is better explained by the Coanda Effect, which describes how a fluid, like air, tends to follow a curved surface, such as an aerofoil.
In this video, John Collins (award winning paper airplane maker and author) explains how the Coanda Effect ensures that airflow stays attached to the wing’s surface, curving around it and being deflected downward. This downward deflection of air is critical because, according to Newton’s Third Law of Motion, the downward push of air results in an equal and opposite upward force—lift.
Understanding the Coanda Effect gives a more accurate picture of how lift is generated and explains why certain wing shapes and angles are more effective. Unlike the Bernoulli-based explanation, the Coanda Effect shows why airflow remains attached to the wing, ensuring the necessary conditions for lift.