Sorry, missed the bit about how does a winc launch work.
Yo fix one end of a wire cable to the glider and the other end to a 150-200 horsepower engine with some safety weak links, cable parachute, winch drum and paying on gear in between. On the order `up slack` the cable is slowly wound in by the winch driver until the glider begins to move, the order `all out` is given and the driver accellerates the winch so that the glider reaches takeoff speed, rises into the air, and at a safe height, is pulled back into a climb at 50 Knots and at least 45 degrees. Climb rate will be 2000 fpm or better. When the max possible height is reached, the cable will release automatically or be released by the pilot. Advantage:- quick and cheap. Aerotows go as high as you are prepared to pay for and usually drop you in a thermal so you have the nail biting (and skillful) bit taken out.
Mike W