This said, I don't know if it exist already, but I would love to make and addon that reproduce a realistic docking system from soft capture to hard dock.
Please do:
https://www.orbiter-forum.com/project.php?issueid=1204, this a Orbiter feature request by me nearly 5 years ago for exactly this.
AFAIK, there's no such add-on at all, it is still the same docking system as from 2003 which is when vessel2vessel docking as we know it today was first implemented.
---------- Post added at 10:50 PM ---------- Previous post was at 10:11 PM ----------
Thanks for the info.
I didn't find actual sound but I studied a bit the NASA docking system, there are some electro-mechanics involved but I bet mostly silent apart if you are very close or if you put your hear on the hull.
The NDS is based on the International Docking System Standard (IDSS) which in itself is based on the Russian APAS (first used by Soyuz 18 back in 1975 to trial it for Soyuz 19 which was the Soviet half of the Apollo-Soyuz Test Project (ASTP) which took place in July 1975. It was later further developed for use on the Soviet Space Shuttles which would dock to the Kristall module of the then new Mir multi-module space station.
But all those plans fell to the wayside once the Soviet Union crumbled. Then it was adapted to work with the US Space Shuttles for the Shuttle/Mir Program which itself was considered Phase 1 of the International Space Station Program. NASA had to pay the Russian's a licensing fee to use the APAS on their shuttles, so NASA-JSC began to develop a US version called the Low Impact Docking System (LIDS) and the first user of this new system was going to be the X-38 Assured Crew Return Vehicle (ACRV) would have replaced the Soyuz as the main ARCV of ISS as the its return environment was far more benign than the Soyuz (in case of a medical emergency).
Eventually, the LIDS morphed into the IDSS, which is fully open for anyone to use, no licensing fees or anything. Both NASA, Boeing and SpaceX have their own versions of the IDSS. The two Internal Docking Adapters (IDAs) converted the two Pressurized Mating Adapters (PMAs) from APAS to IDSS. Only IDA-2, which is attached to PMA-2 on the forward end of Node 2 has seen a docking so far and that was by the SpaceX Crew Dragon during its demo flight last year.
And that's the history of the IDSS, from conception to first use. It will see it's second docking on May 28 when the Demo-2 Crew Dragon docks there.