On Saturday, February 8, 2014 11:50:52 AM UTC-5, Dan Marotta wrote:
The standard setup is to use a Schweizer hook which is rigidly mounted in

pitch and can swivel around the yaw axis.

Yeah but. Why does the tug pilot have to pull anything when a glider kites? The tug pilot should of course have the option to release at any time.

Here is the 1870 patent for something that look a lot like the Schweitzer tow hook. Click on the thumbnail for a drawing. http://rec.aviation.soaring/

The Tost hook still requires the tug pilot to pull a lever (though the automatic "back release" on the glider side is nice.)