> As long as we're talking relative runner lengths of primary and
> secondary runners, I started wondering about having two runners
> per rotor.  I've never been clear about why there are two, and
> wondered if perhaps it had something to do with running up and
> down through the gears (which airplanes do not do).
>
> Could someone provide me with a quick and dirty explanation of
> why we have primary and secondary runners, and why we need them
> both for steady state operation?  Seems as if DIE would also be
> greatly simplified if there were only one runner per rotor.
>

Mazda used it as a simple way to cut down on the amount of fuel/air mixture during idle, and yet have plenty of reserves at redline rpm.