A stall strip is a small aerodynamic device typically attached to the leading edge of an aircraft wing. Its purpose is to modify the airflow over the wing, particularly during high angles of attack, to improve stall characteristics.

How stall strips work and why they’re used?

Initiating Flow Separation

Stall strips are designed to intentionally disrupt the smooth airflow over the wing’s surface at high angles of attack. By doing so, they induce flow separation, where the airflow separates from the wing surface. This separation helps to prevent airflow from remaining attached to the wing’s surface beyond the critical angle of attack, which can lead to an aerodynamic stall.

Preventing Spins and Improving Control

One of the primary reasons for using stall strips is to prevent the aircraft from entering a spin following a stall. By ensuring that the stall starts at the wing root and progresses outward toward the wingtips, stall strips can promote a more stable and controllable stall behavior. This is particularly important for general aviation aircraft and training aircraft, where spin recovery is critical for safety.

Enhancing Control Authority

Stall strips not only enhance aircraft controllability near the stall but also prolong the availability of aileron effectiveness to maintain wing level. By inducing flow separation at strategic points on the wing, stall strips modify aerodynamic forces, offering pilots heightened cues and warning signs as the aircraft approaches stall conditions. This prolonged aileron effectiveness enables pilots to anticipate and respond to stall conditions more effectively, contributing to safer flight operations.

Customization and Adjustment

The design and placement of stall strips can vary depending on the specific characteristics of the aircraft and the desired stall behavior. Engineers may conduct wind tunnel tests and aerodynamic simulations to optimize the placement and size of stall strips for a particular aircraft configuration. In some cases, stall strips may be adjustable or removable, allowing for fine-tuning of the aircraft’s stall characteristics.

Overall, stall strips are a simple yet effective aerodynamic device used to improve the stall behavior and controllability of aircraft, particularly at high angles of attack. They play a crucial role in enhancing safety and stability during critical phases of flight.