Actual zero force with decouplers

[lajoswinkler]

I'm stuck at this challenge. Even with this small decoupler having a zero detach force, it still pushes like a small docking port. It doesn't allow you to do precise maneuvers as it imparts around 1 m/s and when you decouple it. If it says zero in VAB, I want zero pushing. Can we have this fixed?

Also, if someone knows a quick solution to this, I'd really appreciate it.

[Numerlor]

didn't try this but maybe 2 decouplers pointed at each other?

[Gaarst]

Stick another one on the other side of the craft to transfer momentum to (like a Newton cradle). I'm not 100% sure this will work and you may need to use a separator to neglect the mass of the rest of craft that you are detaching.

Edited April 2, 2017 by Gaarst

[StahnAileron]

Odd... I use small decouplers when I recently launched my comsats. I set them to zero force as well since I'm doing precision maneuvers to get them into exact KEO orbits (within a tenth of a second of needed orbital period and within 100 meters difference between Pe/Ap. I'd tried closer, but KER's readouts aren't that precise with large values.) I didn't notice much difference in my velocity. Granted, the satellite was 1 ton and the launcher around 12 tons (SSTO spaceplane), plus I'm doing post-separation maneuvers anyway. So I'm in a different use case. Still, I've had my payload just sitting there in my cargo bay apparently still and looking like it's still attacked until I move my launcher.

Anyway, if I recall, one method of separation was use sepratrons turned 90 degrees inward to destructively disconnect stages. That should result in a zero net force separation.

Only other things I can think of is mirroring/duplicating your launcher on the opposite of the payload so you have even mass distribution on either end for zero net force on the payload on separation.

Oh, BTW, have you checked the part you're using on the payload that connects to the decoupler? I know of parts that have odd colliders or something. Even if the visible model is clear, the colliders may be overlapping. When you decouple the two part, collision detection kicks in and flings them apart. This MIGHT be the case you're seeing. (I mention this because a part I often use, the KANDL RTG NTR from AtomicAge, has a fairing that apparently has a solid collider. Decoupling with the fairing in place flings the fairing and the payload able due to the sudden collision detection, regardless of decoupler settings or the force setting in the engine's CFG. I have to disable the fairing in the editor beforehand.)

[Combatsmithen]

We need true mechanical separators with no pushback force. just a pure unclamp instead of explosive bolts or whatever

[Gargamel]

If you are really needing zero force seperators, why not just use docking ports?  I've never noticed any force from those. 

[Numerlor]

9 hours ago, gargamel said:

If you are really needing zero force seperators, why not just use docking ports?  I've never noticed any force from those. 

They have decoupling force of 10 instead of separators 200

Edited April 11, 2017 by Numerlor

[Technical Ben]

12 hours ago, gargamel said:

If you are really needing zero force seperators, why not just use docking ports?  I've never noticed any force from those. 

Nope. I often use decouplers to separate 2 sections of a craft/station probes in orbit where I have not added any retro engines/sepratrons.

[Gargamel]

8 minutes ago, Technical Ben said:

Nope. I often use decouplers to separate 2 sections of a craft/station probes in orbit where I have not added any retro engines/sepratrons.

I was talking about docking ports, unless you mis-spoke.

I haven't noticed any ejection force, but that may be due to the fact my ships are quite heavy in comparison to the force of undocking.   Usually my ships just sit there, and I fear them redocking by accident (I know theres a built in buffer).

[qzgy]

1 hour ago, gargamel said:

 but that may be due to the fact my ships are quite heavy in comparison to the force of undocking.

Being heavy helps. Try one of the smaller docking ports with like a tiny probe. I just tested a stayputnik on some fuel tanks on the runway and with gravity hacked, it drifted at about 0.2 m/s

[Technical Ben]

On 4/11/2017 at 2:56 PM, gargamel said:

I was talking about docking ports, unless you mis-spoke.

I haven't noticed any ejection force, but that may be due to the fact my ships are quite heavy in comparison to the force of undocking.   Usually my ships just sit there, and I fear them redocking by accident (I know theres a built in buffer).

Typo. Both begin with D, sorry. Yes I use docking ports on really small pod/probes to separate two craft. Not tried it yet in the latest builds, as the larger parts now allow me to launch larger craft, and better physics means I put RCS on most. But in the past I've done a ion craft, no rcs and ion engine facing towards the port, and undocked it with only the docking port to give a push to separate the craft from each other.