This isn't everything you need, but there is a WinPilot polar file you
can get for the Discus A at http://www.winpilot.com/polar.asp.

Unfortunately, different manufacturers like to ask for polars in
different ways. My LX5000 wants the polar's (a,b,c) coefficients and
min and max wing loadings. Cambridge wants (1) best L/D, (2) wing area
in sq meter, (3) best L/D speed in kph, (4) dry weight in kg, (5) speed
at 2 m/s sink in kph, and (6) ballast capacity in liters. You can get
some of that from your glider's manual.

What's the difference between the Discus and the Discus A? SeeYou (my
3.1 version anyway) has polars for "Discus" and "Discus 2". I derived
the C-302 polar numbers by plugging the SeeYou polar numbers for H304CZ
into LXe's Polar tool to get a graph of the polar. From that I read off
the numbers for best L/D speed and speed at 2 m/s sink. I can do that
for you, if "Discus" and "Discus A" have the same polar.

-ted/2NO