auto-rudder?

[GeorgeC]

For that matter, the original premise of "keeping the ball centered" isn't necessarily the proper rudder application. Zero sideslip will be more effective, and zero sideslip diverges from ball centered as soon as you have any power applied.

You are right, and I just learned something. Thanks!

 

[JohnAJohnson]

The F-4D and E both had the same ARI system, providing a maximum 7.5 degrees rudder (out of a possible 30 degrees total each way) with full roll deflection, when the flaps were half down. The system would also move the rudder a maximum of 15 degrees left or right if the flaps were full down. There was no ARI with the flaps up because adverse yaw like most planes, was only an issue at high AOA. The F-4 had spoilers that broke out at 2 degrees of up aileron and took over, countering the drag of the other wing's down aileron. The flaps retracted (because of a blow up switch) if the airplane accelerated above 220 knots or so. So above 220-250 knots, there was no ARI. At all times, unless disengaged, there was a yaw stability augmentation system (AKA Yaw Damper) that used a yaw rate gyro to dampen yaw, and a lateral accelerometer to keep the ball centered. This stability augmentation system, same as the mechanical ARI system could be easily overridden - the pilot always had the full 30 degrees of rudder available at the pedals. So at high AOA with the flaps down, the ARI would do crude corrections and the lateral accelerometer would always be working in the background to fine tune the rudder position around the new reference point set by the ARI system or the pilot's feet. It was not unusual for a new trainee (at Homestead AFB, RTU for F-4s) preflighting his F-4 on a crooked ramp, and complaining because the rudder was offset to the left. When he was asked where the ball was and he replied "out of the cage to the left", he would then understand how the lateral accelerometer worked in his yaw stab aug system.