I hadn't previously heard of the Ackerman geometry with pull-pull controls. After glancing over some references very briefly I still don't quite understand the definate advantage of an Ackerman setup over a linear system, i.e. where the connection points on the horn are on the same plane as the pivot point.
Is it because the pull-pull system is analogous to a cars steering geometry where there is a differential change or different distances that each wheel (or servo arm) travels?
Would there be any disastrous effects with a non-ackerman setup?