The pic gives a good idea of the boom mounted tailplane fixture.
Next winter project for my PIK 20.
I note that the elevator shows the BGA required mod., a downward cusp added to
the Glasfluegel design.
This was supposedly to provide feel at high speeds; found it (1972)
to spoil the feedback and worse, to allow trimming only to 80 kts or so.
This was quite unacceptable to me in for contest. I removed the cusp
and found feel and trim speed now acceptable.

John Firth