We used this method only for paragliders. On that case the initial
acceleration was the key issue (I suspect it's the same for sailplanes
as well - to get control asap). Once the glider is high there is no more
trick. We operated on a 2,2km road that gave 3-400m without wind and
5-600m with moderate wind.
Regards,

/Janos

Gary Boggs wrote:
One of our club members has built a pay-out winch but none of us have any
experience using one. We have done many ground launches with a car from a
dry lake bed with 3000ft of cable and 6 miles of dry lake so we are familiar
with ground launching. If anyone out there has any experience with a
pay-out winch, we would like to know what speeds are best used in the tow
car, and what airspeed in the glider yields the most altitude for a given
runway length? I imagine that the glider should keep his speed at the lower
end of the spectrum, but what speed is most efficient for the tow car? Most
of our launching will be with a 10 to 20 mph wind, our runway is 3000ft
paved. Any knowledgeable input is welcome.