Mike,

That is 'kiting' and is a whole different ball game
that can only work in very strong winds. In 30 years
at a club doing 8000 winch launches a year I have never
witnessed it - although the even-older-than-me members
tell tales of it. The main disincentive at our site
is the risk of excessive lengths of cable being blown
over power lines, trees or structures before it can
be reeled in.

John


At 14:30 06 November 2007, Mike Schumann wrote:
At high enough wind speeds, the maximum altitude is
actually achievable by
letting cable out, rather than winching it in.

Mike Schumann

'John Galloway' wrote in message
...
At the risk of stating the obvious, assuming that
the
winch/cable angle at the top of the winch launch is
a constant, then the height gained by the top of the
launch is simply related to the length of cable left
unwound.

You can work out the effects of different wind speeds,
glider climb angles, cable pulling in speeds etc but,
in the end, the highest possible launch will always
result from a steep climb at a high glider airspeed
but with a low cable speed. That scenario requires
a significant headwind and a winch that is capable
of pulling with sufficiently powerful, but also controllable,
torque at the required, lowish, cable speed.

John Galloway






On 1 Nov., 18:39, 'Neil' wrote:
Ok, I could probably arrange with the winch driver
to experiment, but is
there any definitive guidance on getting the greatest
height off a winch
launch? (eg. Skylaunch).

i.e. if I'm 'driven' at the higher end of the speed
range acceptable to my
gliders placarding, will I get higher or lower than
a lower speed launch?
I used to consider faster meant higher, but last weekend
a most experienced
colleague said you'd end less high, as you spend less
time gaining height.
I'm sure there's a set of graphs that would show a
polar curve type
trade-off, but is there a simple way of looking at
this?

Neil







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