This is an air tractor. Also known as a Pawnee.
https://en.wikipedia.org/wiki/Air_Tractor_AT-802They often have windstruts as they are used for crop dusting and fire fighting. This means they are built like tanks and very good for hauling things like gliders into the air and then sideslipping down very fast to get back on the ground with their wings not in any danger of bending. I attach an image of one doing just that job below.
It isn't my fault you haven't flown many places or experienced different types of gliding. I forgot before, I happen to have an old friend who owns a motor glider and I've been in that too. I expect you'll tell me a glider with an engine is also impossible and that I have been playing too much Kerbal space program.
These aircraft don't 'drop' the cable. They release at the glider end and the ruddy cable dangles around behind them as they come in to land. The buckle release thing is a meaty bit of metal and it bounces and flies around like no ones business as the plane lands. And those cables are pure steel. Get one of those in your prop and its goodnight. They are heavy too.
I do not mean a winch launch. Booker Airfield near me uses a winch. Denham use Tow aircraft. My airprox was with a tow aircraft, not a winch. I was too high for a winch to bother me and there was an aircraft on either end of the rope. Just because you don't have a vast experience of different airfields doesn't mean I do not. You are obviously a club pilot who always flies from the same airfield every single time and have no concept of aviation outside of your little 5 mile bubble.
I'm not interested in your friends. I know more pilots than I care to. I trained with them at a flight school, worked with them, sold aircraft to them, did air shows with them, dated them, lived with them, am related to them and they all think the world is round. They also think that fiat currency is a legit system not based on fraud and backed by central banks with real assets. They can all be blissfully wrong about things they don't look into deeply.