My vote is LS-3a. On the 3, the leading edge of the
horizontal is well in front of the leading edge of
the horizontal. On this one, they are nearly coincident,
as they are on the 3a.

The wing is a single taper, with a curled down tip.
I don't think it is an optical illusion. It also
has the higher taper ratio of the LS-3/LS-3a. Definetly
not a Std Cirrus, as that vintage from Schempp-Hirth
has a slight 'swayback'.

Steve Leonard
Wichita, KS