What is particularly interesting in both the video and the photographs is
the direction the glider is pointing relative to the cable. In the video
the glider can be seen to yaw as the cable tightens and then further yaw
as the it starts to move.
In the photographs it is clear that the glider is pointing to the right of
the direction of the cable AND stangely is pointed in the same direction as
the K13 parked behind it, a co-incidence perhaps. In both cases it would
appear possible that the glider was not lined up with the cable prior to
launch so that as soon as the cable moved yaw was induced. With a CofG
hook the glider will be more unstable about the yaw axis than was the case
with the more forward release on older gliders. Perhaps that might explain
why this appears to be a "new" phenomenon.


At 21:45 24 June 2009, Derek Copeland wrote:
Once a wing drops onto the ground, the glider will almost inevitably
veer
off in the same direction due to ground friction, which is what you see
here and what you also see in my video of a wing drop. The photographer
didn't quite catch the start of this incident, and I am sure that the
glider would have been lined up correctly.

The wing tip runner for the K13 was a very experienced pilot and an ex
syndicate partner of mine. He told me that it was a cold, windy and very
blustery day and that none of our runways lined up with the wind
direction, so there was about a 30 degree cross wind from the right. The
chain of events started with a violent gust that caused the wing to drop
as he let go. The instructor tried to pull off, but his gloved hand
slipped round the round release knob, twice in fact. He was successful
at
the third attempt, but reported that it took a lot more force than he
expected to release under tension. By this time he was airborne, so had
to
take over and fight the glider back onto the ground somehow. What was
interesting was the the eventual landing direction was at right angles
to
the start direction, once the rudder was taken off. The student pilot
may
not have dealt with the dropping wing very well, but there is no
evidence
that he contributed to it.

After this incident, our CFI wanted to fit T handle releases to our
K13s,
but EASA said no because it counted as a major modification and would
require full design approval (very expensive). Bureaucracy gone mad or
what!

Derek Copeland


At 18:54 24 June 2009, bildan wrote:
What I see in that K-13 sequence is the parachute disappearing off the
left side of the frame after it was released. It gives the appearance
the glider was staged at least 30 degrees off the line of sight to the
winch. I also don't see any aileron or rudder applied in the first
frame with the wing on the ground indicating the pilot was WAAY behind
the glider.

Blaming this 100% on a gust seems a reach.