Jon Kraus wrote:
snip

- innermost loop controls roll with ailerons and
taking reference from horizon gyro,

Wrong....

S-tec AP's do not take any info from the AI. They are rate based not
attitude based and get their roll info from the Turn Coordinator.

The GPS Steer function is a true wonder to behold. Both in simplicity
and accuracy. You know not of which you speak... No offense... :-)


It still does not take the short-term heading reference from the GPS,
but it uses the turn coordinator as a replacement for the horizon
roll axis. As is well known, the TC data is part roll speed and part
heading rate, and it can be integrated to create a rudimentary
replacement for the roll reference.

The GPS steering then functions as a setpoint value for the
roll servo. The basic flight dynamics are still there.

The digital signal processing gives an advantage over
the older analog units in thyet it is possible to create
stable long-term (over a couple of seconds) integrators
with the digital way.

--

Tauno Voipio
tauno voipio (at) iki fi