What type of movement do speed brakes primarily affect?

Speed brakes are specifically designed to increase drag and reduce the speed of an aircraft without significantly altering its forward thrust or engine power. When deployed, speed brakes increase the surface area exposed to the airflow, which enhances aerodynamic drag. This additional drag acts to slow down the aircraft, making speed brakes particularly effective in controlling descent rates during landing approaches or in various flight maneuvers where a reduction in speed is necessary.

In contrast to other types of movements, such as roll and pitch, which involve changes in the aircraft's orientation or rotation around its axes, speed brakes primarily focus on deceleration. This functionality is crucial for ensuring safe landing and maneuvering, as controlling the aircraft's speed directly impacts its performance and handling characteristics in the air. Therefore, speed brakes predominantly affect speed rather than the other types of movements involved in operating an aircraft.