"Dan G" wrote in message
...
On Nov 29, 2:57 pm, "Bill Daniels" bildan@comcast-dot-net wrote:
We actually tested the power required to retrieve Spectra and the starter
motor is way more powerful than needed. Not sure what your problem is at
Lasham.

Derek will answer for himself, but I expect they retrieve against the
pay-out brake on the winch, as per normal operation. If you don't, the
drum will keep turning under its own momentum when the retrieve stops
and you'll get cable everywhere. Not good.

Yes, they certainly pull against the heavy payout brake - they have to,
they're using steel cable. You have to keep steel under tension to prevent
tangles. Spectra/Dyneema doesn't need that tension.

Spectra/Dyneema doesn't ball up and tangle like steel so you use much
lighter braking force. In fact, with tension control used for braking, very
light reverse torque is more than enough to prevent problems so very, very
little force is needed to pull out a Spectra cable from a winch designed to
take advantage of Spectra/Dyneema.

To get all the benefits of Spectra/Dyneema, you have to not only modify the
winch, you have to change operational techniques. Just throwing it on an
old steel cable winch and using steel cable operating techniques is
guaranteed to fail - as it did at Lasham.


The cost of Spectra is more like three times the cost of steel not 5
times -
I checked the prices this morning. It takes a LOT of power to pull steel
cable across an airfield - I can pull a mile of Spectra with one finger.

We need verifiable data from retrieve winches. Your tests at Lasham are
not
verifiable since you did no controlled experiments.

Having been to Lasham myself and talked to people there (though not
yet witnessed the retrieve winch itself operating), I'm perfectly
satisfied that what Derek says about the performance of both UHMWPE
and retrieve winches is correct.


Derek says Dyneema doesn't work because it's too expensive, wears out faster
than steel and doesn't provide any aditional height. Evedence from many
other sites successfuly using Dyneema is to the contrary on all points. The
difference is that successful sites did their homework and made all the
neccessary changes.

Bill Daniels