Is it me or are they launching downwind? Look at the cloud shadows. Ok .
the wind is very light.
During the summer lasham does a grid launch for cross country pilots every
weekend. Often the grids are 40+
The grid is usually at one side of the airfield with
crews/marshalls/hangers-on/gawpers accessing form that side with all air
movements on the safe side.
The biggest I have seen was a 2 class national contest a few years ago.
110 gliders in 2 classes lanched in 62 minutes with 12 tugs. ( they then
stream launched another 35 gliders not in the contest)