Roger Long wrote:

There is a note telling
members to check the graph by hand if they are doing something like flying
with lead or gold bars stacked around the rudder pedals.

Our club has spreadsheets for our aircraft that actually create the graphic.
Since I didn't write them, I don't feel comfortable posting them. But it
doesn't appear too complex a task to achieve this. A set of fixed cell
pairs define the fixed shape of the "envelope", and then a final cell pair
- computed, of course - defines the point (hopefully) within the envelope.
A line graphic is drawn from these cell pairs.

- Andrew