On Wednesday, November 2, 2016 at 11:00:06 PM UTC+3, Morris Carter wrote:
for aero tows which is best, and which are dangerous

Just recently discussed here (again)

Most places around the world use 50 - 60 m.

Longer is safer, up to a limit, as it gives the glider pilot more time to react.

Some claim a shorter rope lets you get out of shorter fields. It's true, obviously, but if your field is short enough this makes a difference then I'd question towing out of it at all.

Some claim a shorter rope lets you be in the same airmass as the tow plane in rough conditions. True, on transitions you'll spend less time in the old air mass, but the height difference achieved (assuming no correction by the pilot) before you get into the same air mass will be proportional to the rope length, and the angle of the rope will be inversely proportional to it, so there's no difference. A longer rope gives the glider pilot more time to react, and on a short rope the slalom effect may be severe if the tow plane suddenly sinks in front of you and you don't have lightning reactions.

One factor limiting rope length while I've just thought of and have never seen mentioned befo you don't want the rope length to get much more than the tow plane's thermaling radius, and CERTAINLY not to the tow plane's thermaling diameter!