"Martin Gregorie" wrote in message
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For short runways, a single drum and a retrieve winch is probably
unbeatable.

I know about them but have never seen one in action. How long can the run
be before this becomes impractical?


Not sure - somebody needs to do some believable side by side tests. The UK
retrieve winch operations are still using steel cables on fairly short runs.
Those don't seem to suffer much from lifting two cables. Obviously, Dyneema
cables will have a large effect on retrieve winch operations by reducing the
losses associated with lifting a second cable.

It depends on what you are trying to do. Landing practice or launching into
local ridge lift makes launch frequency the most important thing so retrieve
winches are attractive there. Getting high enough to cruise around for a
while looking for thermals probably means long runs and multiple drums are a
better approach.

Very high launches for training probably eliminates retrieve winches from
consideration.

Bill Daniels