Autopilot speed hold

[microlight]

I've got some flight dynamics that work well to Mach 3, which are not based on the Concorde dynamics (long story). Over Mach 1.1-ish though, the autopilot won't hold speed, and I have to resort to manual throttle control.

The question is this - if Concorde will hold Mach 2 on autopilot and the autopliot settings in the AIR files are the same, does anybody know why my autopilot won't hold speed?

[Moach]

have you tried using MACH HOLD instead of AIRSPEED HOLD?  :)

[microlight]

Yeh, I normally use Mach hold over FL180 rather than Airspeed hold.

Back to the drawing board!