On Thursday, April 5, 2018 at 2:50:21 PM UTC-4, CindyB wrote:
On Sunday, March 25, 2018 at 11:34:44 PM UTC-7, Ramy wrote:
Chain links are often used instead of TOST rings for ground tows behind golf carts, as they are much cheaper. snipped part

Do other had such experience? Is there a reason to be concerned?

Ramy

On the ground, not as much for concern..... unless you are towing on non-level ground and don't want the glider to escape the towing vehicle. A single person on a tip and an unleashed glider might result in ground handling damage.

Chain links for Tost hooks in flight are a bad, BAD idea.
They can release when wanted connected.
They can remain connected when wanting a release (by binding on the beak).

Chain link is typically not a hardened material.
The softness will allow a chain link to be eroded over time in using on a hard Tost beak inside the round collar. Eventually it will conform to the shape of the beak, and not slide off easily. Particularly under normal tow tension.

There is a reason the Tost ring pair has a ROUND ring for the beak. And it is
more expensive due to the process of hardening, and inspection after making.
In this case, please use the right part for the job!

I was once consulted by an AS-K 21 owner that was considering cutting out the
Tost assembly to remount in a different angle, due to the chain links not releasing under aero tow. I told them they could use Tost rings and throw them away every year for the price of cutting up and changing their glider's nose.
They began buying Tost rings.
JS knows the origin of that tale....
True story.

Cindy B

They can remain connected when wanting a release (by binding on the beak).

Couldn't agree more with you, Cindy! Just to elaborate as to why that happens: a normal chain link at yielding load will deform and assume a hour-glass shape. That action nicely swages the link onto the beak.
Heavy duty chains like anchor chains or coal-plow chains have an insert on the inside in support of the link.
The old Tost double ring pair had a small oval ring which connected to the beak. They changed that for exactly the reason described above.

Uli
'AS'