Eric wrote
Though this probably isn't the "electronic aid" Udo had in mind, using a
digital camera would make it even easier today. It could be aimed to
include the flap handle position, and it has it's own clock to time-stamp
the pictures. Many more pictures could be taken for each run instead of
being limited to the 36 a film camera has.

While this makes the data recording easy, the ASI (including the pitot and
static if you want to compare between gliders) and altimeter still need to
be carefully calibrated.

This is a good idea as the data is displayed digitally. I can not remember
if speed, altitude
and temperature can be displayed simultaneously on the L Nav.
I wonder if a small digital movie camera would have a good a enough
resolution to do the job.
Regards
Udo