Earlier, noel.wade wrote:

Where is your glider's CG envelope?

Dick Schreder generally recommended 25% to 40% of MAC; most sailplanes
are similar. I generally recommend 25% to 35% for the HP-18.

Basically, work back through the wing dimensions to find out what the
MAC is. Then find the spot on the wing where its chord is the same as
the MAC. Then find the longitudinal location of that wing station.
That's what the CG envelope relates to.

The final Article on the HP-18 shows how find the CG envelope in
relation to MAC and determine minimum and maximum cockpit weights from
it. The one thing in the Article I take issue with is that Dick assumes
that the mean chord is the same as the average chord, but they're not
the same. However, the difference is so small that it makes no
practical difference in this particular case:

http://www.soaridaho.com/Schreder/Sc...976_HP-18.html

Thanks, Bob K.