Dave,

there are several of these hydrostatic winches around, one of them at
my old club in Germany - see the Skylaunch album under K,
Kamp-Lintfort.
This winch is a technical marvel but also very expensive to maintain
(Fluid, filters, HP-Hose, etc.) Another one was built in cooperation
with Danfos, I believe. I think this is a very complex design, too
complex for a group of amateurs to build.

Ulrich Neumann


Dave Martin wrote in message ...
Unless a mass batteries are used, the logistic of supplying
power to several possible winch stations around and
airfield to provide a days winching seems very expensive,
although a 'plug in and play' system would be an ideal
way of operating.

Has anyone considered the use of 'Hydrostatic Pumps'

Using the main engine to drive a hydraulic compressing
pump, as used on mechanical diggers etc, a hydrostatic
pump on each individual drum would provide the power
to launch the glider.

It would remove the need for complex mechanics and
by a simple system of taps could drive any one of a
number of individual drums.

Using deep sided drums without pay on gear would reduce
build costs and time.

Building the winch on a trailer would be simple, mobile
and may be cheaper than using complex mechanical drives.
It would also be simple to maintain. I understand modern
pumps can be programmed and controlled electronically.


The main pumps can provide sufficient power as can
be seen on mechanical diggers, but they are only pumping
us a telescopic ram. I believe they are used on slow
moving agricultural equipment to provide drive to the
main wheels.

The question is could the pumps provide the power and
speed to drive a drum for several minutes to enable
a glider to be launched.

Similar pumps can be seen at

http://www.casappa.com/

Although I am sure they will be available throughout
the world.


Dave