Kontrollflate

Kontrollflate refers to a movable surface on a vehicle, most commonly an aircraft, that can be deflected to influence the aerodynamic forces acting on the vehicle. By changing the flow over the wing or tail, a kontrollflate alters lift, drag and the moment about the aircraft’s axes, enabling control of roll, pitch and yaw.

Typical kontrollflater on fixed-wing aircraft include ailerons for roll, elevators for pitch and a rudder for yaw. Other surfaces used for attitude or trim control are trailing-edge flaps, flaps, slats, spoilers and airbrakes, as well as canards on some configurations. In fly-by-wire aircraft, kontrollflater are actuated by electric or hydraulic systems and controlled by the flight computer, often with safeguards and redundancy.

The function of a kontrollflate is to produce forces and moments through deflection. When a surface is moved, the altered airflow creates a difference in pressure between its upper and lower surfaces, generating lift or drag and a corresponding pitching, rolling or yawing moment. The system must provide sufficient control authority while preserving stability and avoiding adverse dynamic effects such as flutter or undesirable control surface flutter.

Design considerations include structural strength, weight, actuator power, response time, and reliability. Control surfaces must operate safely across a wide range of speeds, altitudes and loading conditions, and they are typically integrated with the aircraft’s stability and control augmentation systems. The term Kontrollflate can also be used more broadly to refer to any movable surface that provides controllability in fluid-dynamic applications.