Does anyone use a tug tow hook that releases automatically whenglider kites?

On Sunday, February 9, 2014 5:27:23 PM UTC-5, son_of_flubber wrote:
This topic was buried in a drifting degenerate thread. I'm wondering if anyone knows more about the tow hook innovation mentioned below by UH.



On Saturday, February 8, 2014 9:31:13 AM UTC-5, son_of_flubber wrote:



Why does the pilot need to pull the release if the glider kites? Why is the release for a deadly tow position not fully automatic? Is a simple purely mechanical, totally foolproof and 100% automatic release not possible? As the guy in the glider, I would be fine with a 100% automatic release. If I kite, release me immediately.





On Sunday, February 9, 2014 5:05:52 PM UTC-5, wrote:



There was a design and prototype of a release like this created many years ago and published, I believe, in Soaring magazine. I know if no one that has adopted this which makes it fairly clear that this is not perceived as a huge problem.



While going through old stuff this 1980 Sailplane and Gliding article surfaced:

https://drive.google.com/file/d/0B1O...it?usp=sharing

At 14:07 04 May 2014, Karl Striedieck wrote:
On Sunday, February 9, 2014 5:27:23 PM UTC-5, son_of_flubber wrote:
This topic was buried in a drifting degenerate thread. I'm wondering
if
=
anyone knows more about the tow hook innovation mentioned below by UH.
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=20
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On Saturday, February 8, 2014 9:31:13 AM UTC-5, son_of_flubber wrote:
=20
=20
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Why does the pilot need to pull the release if the glider kites? Why
is=
the release for a deadly tow position not fully automatic? Is a simple
pur=
ely mechanical, totally foolproof and 100% automatic release not
possible?
=
As the guy in the glider, I would be fine with a 100% automatic release.
If=
I kite, release me immediately.
=20
=20
=20
=20
=20
On Sunday, February 9, 2014 5:05:52 PM UTC-5,
wrote=
:=20
=20
=20
=20
There was a design and prototype of a release like this created many
ye=
ars ago and published, I believe, in Soaring magazine. I know if no one
tha=
t has adopted this which makes it fairly clear that this is not perceived
a=
s a huge problem.
=20


While going through old stuff this 1980 Sailplane and Gliding article
surfa=
ced:

https://drive.google.com/file/d/0B1O...dit?usp=3Dsha=
ring


Karl, that's the one we developed following the first set of trials at
Wycombe Air Park. It didn't actually work, here is an extract from my
report:

Attempts to produce a tow-plane hook that would release automatically were
unsuccessful for reasons that became apparent later........

The photo sequence also showed that at no time was the glider at an angle
greater than 30 degrees above the tow-plane’s centre-line. However, of
course once the glider has pitched up, the wings generate considerable
extra lift and that extra lift provides extra load on the rope. With a
large, heavy glider it is easy to exceed weak link breaking strains and
with a lightweight machine the tension can easily rise to 700 lbs or so.
With that much load on the rope, quite a small upward angle provides enough
of a vertical component to produce the results described.
Â*
That of course is the reason that attempts to produce a hook that released
if a certain angle was exceeded were unsuccessful. The, quite small, angle
between the rope and the fuselage centreline needed to trigger the
“Kiting� when the glider is pitched significantly nose-up is not much
greater than the amount of out of position commonly experienced in
turbulent conditions. We did build an experimental hook and tried it, but,
set to an angle that prevented “Kiting� it occasionally dumped an
innocent glider in turbulence, and set to an angle that prevented that, it
didn’t prevent the “Kiting�. What was needed was a hook that
responded to the vertical component of the load, not the angle at which it
was applied, and that problem we decided was beyond us (at least in a form
robust and fool-proof enough to be attached to the rear end of a
tow-plane).