On Monday, 29 April 2019 17:20:34 UTC+2, Papa3 wrote:
FWIW... We found that zig-zag tape in front of control surface seals of our Grob Twin Astir made a significant difference in handling and control forces. Being a standard airworthiness glider, it's nice that the TC owner actually has a service letter for this:

http://www.ltb-lindner.com/service-l...%20seals .pdf

As a person who trained on one of these "concrete swans", I think anything that improved the handling would be appreciated. Will give the zig-zag tape a try.