At 10:58 08 April 2019, Senna Van den Bosch wrote:
I'm seeing this more and more but have no idea what they're
called. Refer
to this pictu
https://cdn.jetphotos.com/full/6/53013_1459261993.jpg
This was Stefan Langer's Libelle, it's got those black plastic(?)
thing at
the aileron and wing. So does this Cirrus:
https://cdn.airplane-pictures.net/images/uploaded-
images/2017/10/14/975766.jpg

What are they called and do they help in performance? Would it
be worth
installing?

They are aerodynamic "fences". Standard on inboard end of
flaps/faperons on many gliders, DG800, Antares and others.
All mods make you go faster, no?