On Aug 23, 2:28*am, bildan wrote:
On Aug 19, 2:23*am, Derek C wrote:


Dyneema is wonderful stuff and it will last up to 15x steel but it
needs a different rope path design and handling protocol.

At our somewhat abrasive airfield at Lasham (UK) we normally get about
1900 launches from a steel cable and the one trial Spectra UHMWPE
cable we tried lasted 2500 launches. The winch we used for this trial
was a modified Tost fitted with what Bill calls sheaves, level wind
paying on gear and specially reinforced drums to prevent drum-
crushing. All the parts that came into contact with the cable had been
highly polished as recommended. According to Bill that cable should
have lasted for 28,500 launches, which is over ten times what was
actually achieved! Other users of UHMWPE (Dyneema or equivalent) cable
have reported similar results to what we found. I wonder how many
launches Bill's 'American Superwinch' has carried out so far?

I believe that Bill has put the cause of winch launching in the US
back by at least 5 years by insisting that only fancy and very
expensive computer controlled diesel hydraulic or electric winches
fitted with Dyneema are capable of giving safe launches. This is in a
country where there are many potential donor vehicles fitted with
suitably large powerful engines and good automatic gearboxes that
could be used as a basis for good and low cost conventional winches.

Derek C

This is yet another in a long list of your gross fabrications and
lies. *Can you point to any source where i wrote 28,500 launches on
one rope?

To quote your posting on 18th August at 11.32:

"Dyneema is wonderful stuff and it will last up to 15x steel but it
needs a different rope path design and handling protocol."

Our steel cables last about 1900 launches on an airfield where you
always have to run over two 50 yard wide concrete or asphalt runways,
so I multiplied 1900 x 15 which makes 28,500.

The only "re-invention" is your adoption of our 50 year old technology
using big V8's and automatic transmissions and claiming it as your
idea. *We knew it was a bad idea long before you even heard of it.

Well you need a big powerful engine to power a winch and big gas or
turbo-diesel V8s are ideal for this. We are using modern engines and
gearboxes, not 50 year old ones.

Yes, I emphatically do not want the US to adopt UK methods or winch
designs. *They are extremely uninformed and dangerous - as your
accident record proves. *Geez, you guys still use steel cable!- Hide quoted text -

Strange therefore that German winches are generally very similar in
design to UK winches, and indeed quite a few British Skylaunch winches
have been sold to German and French gliding clubs. The trend at the
moment is to use polyrope cable, which is stronger and lighter than
steel, and costs slightly less. We have nothing against Dyneema apart
from the fact it costs 6 times more than steel cable (but doesn't last
6 times longer) and can cause handling difficulties, as described by
Andreas Maurer from the Laudau club in Germany. The UK winch
launching safety record has recently been very good, although we had
one fatality last year when a pilot rotated too quickly. I seem to
remember that you were recommending very rapid ground run
accelerations and rotations at one time, which are dangerous for a
number of reasons. The Germans call these 'Kavalierstarts' and have
stopped doing them after a number of fatal flick spin accidents.

Derek C