At 03:26 18 March 2009, bildan wrote:


Tension controlled winches are certainly safer and provide higher
launches than speed controlled ones - any winch with an automatic
transmission is speed controlled since that's what the automotive
drive train was designed to do.

I'm not sure I follow the rest of your post. Hopefully an English
translation will be available.

Short of fitting a speed controlling governor, I don't think that any
current winches are 'speed controlled'. Some earlier diesel powered
winches did have this arrangement, but it was found not to work. During a
properly controlled winch launch the motor and drum speeds reach a maximum
as the glider lifts off, and then decrease during the rest of the launch,
due to vector effects and wind gradients.

Winches with automatic transmissions , such as the Tost and the Skylaunch,
will give perfect good constant pull/tension launches as long as you use an
appropriate throttle or power setting. The Tost depends on the skill of the
driver to do this, but the Skylaunch has an adjustable throttle stop that
you can pre-program according to the glider type and headwind.

Derek Copeland