Hi Mike, I agree with what you say, that the airspeed will increase beyond
the car's groundspeed.

Typicaly if the car is doing 60 knots and the glider pitches up quickly to
a rope angle of 60 degrees, it will now be just 200 x cos 60 = 100 feet
from the car horizontally.

If it does this climb in two seconds, that means an additional 50 ft / sec
which is an additional 30+ knots. Making a total of 90 knots at the
back-release.

This makes the glider now 30 knots faster than the car, so it would
overtake the car.

Pete



My back-of-envelope analysis suggested that the angle of the short
rope at the glider would increase more quickly than that of the long
rope and that this could result in a rapid increase of tension. This
is especially true if the pilot fails to control the angle of ascent
as this change occurs, it could create a slingshot effect that
accelerates the glider and rapidly increases line tension.

We'll have to wait for an analysis of the video to really know what
happened, of course.

Mike