Õhupinnad

Õhupinnad, or airfoils, are shapes that produce lift when moved through a fluid, most commonly air. They are fundamental to the design of aircraft wings, helicopter blades, propellers, and even the sails of boats. The characteristic shape of an airfoil is typically curved on the top surface and flatter on the bottom. This asymmetry is crucial for generating lift.

When an airfoil moves through the air, the air flowing over the curved upper surface must travel a greater distance than the air flowing under the flatter bottom surface in the same amount of time. According to Bernoulli's principle, this faster-moving air on top creates lower pressure than the slower-moving air on the bottom. The difference in pressure results in an upward force, known as lift, which counteracts gravity.

The angle at which the airfoil meets the oncoming air, called the angle of attack, also plays a significant role. Increasing the angle of attack generally increases lift, but only up to a certain point. Beyond this point, the airflow can separate from the upper surface, leading to a loss of lift and a stall. The specific shape and design of an airfoil are optimized for different applications, balancing the need for lift with considerations like drag reduction and stability.