Spin

Z Goudie wrote in message ...

That old red herring again!

The glider is flying in an airmass which is moving
over the ground at a constant rate. No additional
acceleration is required apart from that normally needed
in a turn to supply the turning force.

There may be some effect caused by descending/putting
the lower wing down through any wind gradient but this
actually improves the situation as the air is moving
'away' from the path of the glider more slowly and
will consequently cause some increase in airspeed.
(You can try the opposite of that effect by pulling
up from a downwind racing finish through a strong wind
gradient; watch the airspeed decay at an alarming rate).

The biggest problem is that the apparent speed over
the ground in say a 15kt wind jumps by 30kts and results
in people trying to reduce the ground rush by raising
the nose with no reference to the ASI.

We have very nice herring in NL, not red however.

Indeed I made a wrong supposition in my calculation of a 10° pitch
angle required during the turn back curve of the DG500 to the
airfield.

A steeper pitch angle then the pilot obviously applied would have
helped him a lot though to keep the glider from stalling and spinning
in.
The comment of one of our aerobatic pilots is that the DG-pilot flew
to slow in the last part of the flight and a full spin with crossed
controls (right rudder and left stick) evolved. The air may have been
very turbulent in the lower layer because of several obstructions on
the field.

Karel