Vmc decreasing with increasing altitude.
Whilst I'm happy to accept that Vmc decreases with increasing altitude due to a reduction in turning moment as a result of reducing thrust from the live engine(s) could anyone explain to me the following? If thrust is reducing as a result of decreasing pressure or increasing density altitude then surely the restoring force generated by the rudder must be reducing as well thus requiring a higher velocity to maintain control. The obvious explanation is that it is the thrust that is being affected to a greater degree. But why?