In aeronautics, a spoiler (sometimes called a lift spoiler or lift dumper) is a device which increases the drag and decreases the lift of an airfoil in a controlled way. Most often, spoilers are hinged plates on the top surface of a wing that can be extended upward into the airflow to spoil the streamline flow. By so doing, the spoiler creates a controlled stall over the portion of the wing behind it, greatly reducing the lift of that wing section.
Spoilers differ from airbrakes in that airbrakes are designed to increase drag without disrupting the lift distribution across the wing span, while spoilers disrupt the lift distribution as well as increasing drag. However, flight spoilers are routinely referred to as "speed brakes" on transport aircraft by pilots and manufacturers, despite significantly reducing lift.
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