The advance angle compensates for aerodynamic phase lag in a rotary-wing system. When a pilot moves the cyclic to tilt the rotor disk, the maximum aerodynamic force must occur 90 degrees before the desired physical tilt due to gyroscopic precession. The advance angle builds this 90-degree offset directly into the mechanical linkages between the swashplate and the blade grips.
Heard on the job
Check the advance angle on the pitch links during the rigging process to ensure cyclic inputs phase correctly.