On Aug 2, 7:43*pm, Dave Springford wrote:
Andy,

Your 50:1 math is right and wrong at the same time. *What is missing
is the fact the the centre of the 3 km finish cylinder is located at
the opposite end of the 4000 ft landing runway. *This means that when
you cross the finish line at about 200 ft agl you are about 1.8 km
from the touchdown point (and 3 km from the other end of the runway).
This gives L/D of 30:1 to touchdown which is sufficient for the ships
flying in the 15/18/ Open Classes.

.... and also add that the glider will probably be flying faster when
reaching the finish ring, so will have a bit more energy to spare

or if it doesn't, it can land short if necessary