Wing Launch - Can it pull your wings off?

On Aug 16, 8:19*am, Andreas Maurer wrote:
On Sun, 15 Aug 2010 19:56:16 -0700 (PDT), bildan
wrote:

That's basically what you get from the new winch
designs. *Easier, safer launches with greater performance.

Nope.

Dyneema is an exception. *It has been proven safer than steel cable by
every industry that has adopted it - there's lots of industrial safety
data on that. *Besides being safer, it's just way nicer to work with.

Hmmm... on my airfield (we were the first ones to use Dyneema) we
already had more than only a couple of incidents that were directly
related to the use of Dyneema and wouldn't have happened with steel
cable. We came to the conclusion that -at least on my airfield- steel
cable offers more advantages than disadvatages than Dyneema.

Cheers
Andreas

I very much doubt yours was the first airfield to use Dyneema since
that would have been in 1998 in Germany and I strongly suspect the
analysis of your incidents was seriously flawed. Dyneema is safer,
period. Airfields have no influence on that.

However, simply replacing steel with Dyneema and attempting to use the
same procedures as with steel will cause problems. Those are
transition issues, not Dyneema issues. The winch must be modified and
the operational rules must be changed to make a successful transition.

bildan wrote:
Dyneema is safer, period.

How so? Dyneema isn't elastic, so it doesn't snap back when it breaks,
but that's the only difference safetywise.

the operational rules must be changed to make a successful transition.

Which operation rules would these be? At our field, we successfully
changed from steel to Dyneema a couple of years ago without changing any
operation rules whatsoever. What did we miss? Of course Dyneema has a
slightly different feel, especially for the winch driver, but that's no
change in operation rules.

On Aug 16, 4:02*pm, bildan wrote:
On Aug 16, 8:19*am, Andreas Maurer wrote:





On Sun, 15 Aug 2010 19:56:16 -0700 (PDT), bildan
wrote:

That's basically what you get from the new winch
designs. *Easier, safer launches with greater performance.

Nope.

Dyneema is an exception. *It has been proven safer than steel cable by
every industry that has adopted it - there's lots of industrial safety
data on that. *Besides being safer, it's just way nicer to work with..

Hmmm... on my airfield (we were the first ones to use Dyneema) we
already had more than only a couple of incidents that were directly
related to the use of Dyneema and wouldn't have happened with steel
cable. We came to the conclusion that -at least on my airfield- steel
cable offers more advantages than disadvatages than Dyneema.

Cheers
Andreas

I very much doubt yours was the first airfield to use Dyneema since
that would have been in 1998 in Germany and I strongly suspect the
analysis of your incidents was seriously flawed. *Dyneema is safer,
period. *Airfields have no influence on that.

However, simply replacing steel with Dyneema and attempting to use the
same procedures as with steel will cause problems. *Those are
transition issues, not Dyneema issues. *The winch must be modified and
the operational rules must be changed to make a successful transition.-

Why? We successfully ran a comparative trial with UHWPE cable on one
drum and steel cable on the other drum of a slight modified two drum
Tost winch (mainly to prevent drum crushing, which is a known problem
with UHMWPE synthetic cables). The winch drivers had no difficulty
coping with either type of cable.

Derek C

On Mon, 16 Aug 2010 08:02:39 -0700 (PDT), bildan
wrote:


I very much doubt yours was the first airfield to use Dyneema since
that would have been in 1998 in Germany
and I strongly suspect the
analysis of your incidents was seriously flawed. Dyneema is safer,
period. Airfields have no influence on that.

Bill, I really admire your ability to judge a situation from the other
side of the pond.
You neither know about the incidents we had, nor you have the
slightest idea about the enviroment our Dyneema is operated in.

Yet you dare tto " I strongly suspect the analysis of your incidents
was seriously flawed".

Bold, Sir. Very bold.
Unfortunately you simply have no clue.



Andreas

On Mon, 16 Aug 2010 17:22:19 +0200, John Smith
wrote:


Which operation rules would these be? At our field, we successfully
changed from steel to Dyneema a couple of years ago without changing any
operation rules whatsoever. What did we miss? Of course Dyneema has a
slightly different feel, especially for the winch driver, but that's no
change in operation rules.

We are having problems with cable breaks in crosswind situations -
Dyneemy tends to float for a long time and gets blown all over the
place even if the wind is weak. We had a couple of close calls until
we learned the hard way that we had to stop the complete operation
(including landings of powered aircraft) on the airfield until the
Dyneemy cable has definitely been moved out of the way (something that
usually takes ten to fifteen minutes). The light Dyneemy rope lies on
the grass and can easily be picked up by the gear of any passing
aircraft.
Combine this with an increased number of cable breaks compared to the
steel cable, and you can imagine that the Dyneemy cable costs us some
headaches...


An other problem unique to the Dyneemy cable is a nearby road (1.500
ft away) that already got blocked by a broken Dyneemy cable.

In comparison, our steel cables fall more or less vertically (even in
string winds), causing us no such problems.

We operate two winches on my airfield, one using Dyneema, one steel
cable.


Cheers
Andreas

Andreas Maurer wrote:
We are having problems with cable breaks in crosswind situations -
Dyneemy tends to float for a long time and gets blown all over the
place

Ah, ok. Depending o your situation this may indeed be a problem. At our
site it's not, luckily.

Combine this with an increased number of cable breaks compared to the
steel cable,

We do not have more cable breaks with Dyneema than we had with steel. We
did have some breaks at the beginning but quickly learned how to avoid
them by more careful handling. Particularly never cross two cables as
the friction heat when one is pulled over the other will cut them, and
the winch driver must timely cease to pull.

On Aug 16, 1:15*pm, Andreas Maurer wrote:
On Mon, 16 Aug 2010 17:22:19 +0200, John Smith

wrote:
Which operation rules would these be? At our field, we successfully
changed from steel to Dyneema a couple of years ago without changing any
operation rules whatsoever. What did we miss? Of course Dyneema has a
slightly different feel, especially for the winch driver, but that's no
change in operation rules.

We are having problems with cable breaks in crosswind situations -
Dyneemy tends to float for a long time and gets blown all over the
place even if the wind is weak. We had a couple of close calls until
we learned the hard way that we had to stop the complete operation
(including landings of powered aircraft) on the airfield until the
Dyneemy cable has definitely been moved out of the way (something that
usually takes ten to fifteen minutes). The light Dyneemy rope lies on
the grass and can easily be picked up by the gear of any passing
aircraft.
Combine this with an increased number of cable breaks compared to the
steel cable, *and you can imagine that the Dyneemy cable costs us some
headaches...

An other problem unique to the Dyneemy cable is a nearby road (1.500
ft away) that already got blocked by a broken Dyneemy cable.

In comparison, our steel cables fall more or less vertically (even in
string winds), causing us no such problems.

We operate two winches on my airfield, one using Dyneema, one steel
cable.

Cheers
Andreas

Your statements have graphically demonstrated why you have problems
with Dyneema.

Call in an expert like Klaus Fey (www.eqip.de) and he'll show you how
to make it work.

On Aug 16, 11:06*pm, bildan wrote:
On Aug 16, 1:15*pm, Andreas Maurer wrote:





On Mon, 16 Aug 2010 17:22:19 +0200, John Smith

wrote:
Which operation rules would these be? At our field, we successfully
changed from steel to Dyneema a couple of years ago without changing any
operation rules whatsoever. What did we miss? Of course Dyneema has a
slightly different feel, especially for the winch driver, but that's no
change in operation rules.

We are having problems with cable breaks in crosswind situations -
Dyneemy tends to float for a long time and gets blown all over the
place even if the wind is weak. We had a couple of close calls until
we learned the hard way that we had to stop the complete operation
(including landings of powered aircraft) on the airfield until the
Dyneemy cable has definitely been moved out of the way (something that
usually takes ten to fifteen minutes). The light Dyneemy rope lies on
the grass and can easily be picked up by the gear of any passing
aircraft.
Combine this with an increased number of cable breaks compared to the
steel cable, *and you can imagine that the Dyneemy cable costs us some
headaches...

An other problem unique to the Dyneemy cable is a nearby road (1.500
ft away) that already got blocked by a broken Dyneemy cable.

In comparison, our steel cables fall more or less vertically (even in
string winds), causing us no such problems.

We operate two winches on my airfield, one using Dyneema, one steel
cable.

Cheers
Andreas

Your statements have graphically demonstrated why you have problems
with Dyneema.

Call in an expert like Klaus Fey (www.eqip.de) and he'll show you how
to make it work.- Hide quoted text -

- Show quoted text -

I agree with Andreas. Synthetic UHMWPE cable does drop more slowly
than steel and does have a much greater tendency to drift sideways in
a crosswind, especially after a cable break. If the cables get crossed
it is very easy to cut right through synthetic cable, whereas steel
cables are unaffected. The main reason not to use it though is cost.
Dyneema is nearly 6 times more expensive than steel but lasts only
slightly longer, and can be easily wrecked in one incident if it gets
caught around any bit of steelwork during a launch.

Derek C

On Aug 15, 8:21*pm, Andreas Maurer wrote:
On Sun, 15 Aug 2010 10:29:49 -0700 (PDT), sisu1a

wrote:
Modern winching is pretty much a science and has come a long way since
the 60s so it does not do the soaring community (US at least...) a
favor to combine it all into single raw statistics cause it paints a
negative biased picture based on irrelevant data. *

Hmmm... I beg to differ.
Modern winching has very much in common with winching in the 60s.
The only difference is that the winches grew stronger in accordance to
the rising weight and speed of the gliders, but otherwise -at least in
Germany- very little has changed. Apart from the stronger engines the
rest of the equipment as well as the procedures are still the same as
fifty years ago.

It is not necessary (Bill - I know you are going to cry out now *to
have the latest state-of-the-art gizmos (telemetry, plastic cables,
advanced speed control) to perform a perfectly safe and satisfactory
winch launch.

Cheers
Andreas

I think that one of the most important safety changes we have made in
the UK is the addition of 'Eventualities' to the pre-flight check
list. That is to remind pilots to plan for the possibility of a launch
failure and also applies to aerotows. No fancy computer controlled
winches or other gizmos required.

Derek C

On Aug 15, 8:21*pm, Andreas Maurer wrote:
On Sun, 15 Aug 2010 10:29:49 -0700 (PDT), sisu1a

wrote:
Modern winching is pretty much a science and has come a long way since
the 60s so it does not do the soaring community (US at least...) a
favor to combine it all into single raw statistics cause it paints a
negative biased picture based on irrelevant data. *

Hmmm... I beg to differ.
Modern winching has very much in common with winching in the 60s.
The only difference is that the winches grew stronger in accordance to
the rising weight and speed of the gliders, but otherwise -at least in
Germany- very little has changed. Apart from the stronger engines the
rest of the equipment as well as the procedures are still the same as
fifty years ago.

It is not necessary (Bill - I know you are going to cry out now *to
have the latest state-of-the-art gizmos (telemetry, plastic cables,
advanced speed control) to perform a perfectly safe and satisfactory
winch launch.

Cheers
Andreas

I think that one of the most important safety changes we have made in
the UK is the addition of 'Eventualities' to the pre-flight check
list. That is to remind pilots to plan for the possibility of a launch
failure and also applies to aerotows. No fancy computer controlled
winches or other gizmos required.

Derek C