On Wed, 01 Sep 2010 15:37:24 +0200, John Smith
wrote:

Lately there has been a discussion re Dyneema in this group.
Incidentally, on the DG home page there's an interesting article to this
theme (originally published by "Magazin Segelfliegen"). It's German and
I'm not aware of an English translation.
http://www.dg-flugzeugbau.de/windenseil-d.html


Very good analysis that is completely consistent with out experiences.

A quick translation of the conclusion:

--- snip ---
Most users will not assess the performance gain, but the simple
handling of Dyneema as its main benefit, especially if there are more
than two cables or great lengths to be pulled on loose surfaces.

Dyneema cable only reaches a longer life in an enviroment where steel
cables have to be replaced prematurely because of bad winch design and
adverse ground conditions. Under normal conditions, its life with
about 3,000 departures per cable is the same, but Dyneema is 3 to 5
times more expensive. Not all of the operators who have tested Dyneema
have kept using it.

Not to be underestimated is the cost and effort of the adaptation of
the winch to Dyneema. Because of its high price much time is being
spent with repaires and reduced cable tensile strength towards the end
of its life cycle.

It is recommended to use Dyneema only if all other optimization
possibilities have been utilized.

--- snip ---


Andreas