Speed brakes are high-drag devices designed to help aircraft descend faster without gaining excess speed. They're especially useful when a pilot needs to increase the descent rate without shocking the engine by suddenly cutting power, a practice known to cause engine wear. Speed brakes are often deployed during descent or landing when controllers issue a slam-dunk directive: Get down fast, but don't overspeed.
Unlike spoilers and winglets (curved tips on aircraft wings), speed brakes are used purely to add drag. They don't directly interfere with lift. In general aviation aircraft like the Mooney, speed brakes pop up from the wings to disrupt airflow and slow the plane. They're electrically controlled and don't affect the plane's handling at lower speeds, which makes them a flexible tool for descent planning and airspeed control.
Jets and turboprops also use speed brakes, sometimes called the boards, to manage glideslope and maintain control at high descent rates. Turbine aircraft are especially clean aerodynamically, and even with engines at idle, they can easily accelerate in a dive. Speed brakes solve that by doubling parasitic drag and letting pilots maintain safe descent speeds.
While the drag helps with descent management, speed brakes also prevent excessive cooling in piston aircraft, preserving engine health. Importantly, they don't disrupt flight balance and can be used right up to redline airspeeds.