ASK-21 Weight and Balance

I'm trying to make sense of the weight and balance section in the
ASK-21 manual but having no success. They give an equation for r sub
R, which I assume is the empty CG, but it's not specifically called
out. The units don't balance; there is length on one side of the
equation and length squared on the other. There is an example given
for calculating "inflight CG" and the results seem to be out of
limits but they don't comment so I'm not sure I've got that right.
There is a Load Envelop with Empty Weight on the abscissa and r sub R
on the ordinate. Where does the in flight CG come in? Or is r sub R
also the inflight CG

At 360kg (the nominal empty weight of the aircraft) there is only 8 mm
of CG range within the envelop. Is it really that small? I
understand the Schweizer weight and balance calculations but the
English translation of the Schleicher manual has me puzzled.

Any help would be appreciated. Thanks.

Carl