Note that the drawing on p.28 of the document referenced by John Smith was
taken from a series of photos taken with a motor drive camera during a
deliberate upset of a Supercub towing a K8 during trials many years ago.
Note that the rope angle to the tug hardly changes.

See http://www.glidingmagazine.com/Featu...cle.asp?id=327 , where Chris
Rollings who was flying the K8 describes what happened. The PA18-180 was
being flown by Brian Spreckley.

W.J. (Bill) Dean (U.K.).
Remove "ic" to reply.


"John Smith"
wrote in message ...

The document at the following reference may be of interest
- in particular pages 28 - 30

https://www.gliding.co.uk/bgainfo/cl...rotownotes.pdf .

also see my edit re the tow plane diving


At 17:24 17 September 2006, John Smith wrote:

A simple question to all the participants in this thread
- How many off you have actually experienced piloting
a tow plane when the glider has kited behind you?
As a tow pilot who has had it happen at 500 feet agl
and did survive I can state that it is not just the
angle of the rope but also the high loads imposed that
prevent release of the rope by the tow plane. This
affects all types of release. You have a tow plane
'most likely at full power' trying to dive at a steep
angle and a glider virtually winch launching of the back of it - quite a
high loading I can assure you and one that decelerates the tow
plane rapidly. Secondly the upset occurs because of
the upwards load from the glider overcoming the maximum
down load able to be applied at the tow planes tailplane.
This effectively stalls the tailplane in an inverted
sense and the tow plane is actually pitched rapidly
nose down with very little acceleration and indeed
speed. If the rope breaks or releases it is actually
necessary to accelerate the tow plane in its nose down
attitude to gain sufficient speed to pull out of the
nose down attitude.
And NO, I really don't want to experience it again.
With reference to the original question I would strongly
advise the fitting of weak links to all glider tow
ropes regardless of the supposed breaking strength
of the rope used.
PS I do operate at both ends of the tow rope.