On Docking and RCS--does this ever happen to you?

[rodion_herrera]

I've noticed that on both 0.19 and 0.20, whenever two spacecraft attempt to dock, and both spacecraft have RCS on, even before they are physically docked, that moment when the "magnets" start sensing each other, a "magical" electronic connection is established, so that the RCS systems on BOTH craft start to act as ONE system. Now okay, in reality, that obviously CANNOT happen because there is no real connection yet. And what's more, in KSP, once that happens, and you're dealing with two very differently configured spacecraft, the actual "HARD DOCK" takes place longer, because I think this "phantom" RCS-we-think-as-one that happens, actually screws up the process of getting to a hard dock. I know this, because the moment I turn off the RCS on one or both the spacecraft, a successful hard dock then follows after a few seconds.

This phenomenon (though not really accurate because this event happens only on truly docked spacecraft in real life) is akin (but ironically opposite) to that situation in Apollo 13, wherein Lovell et. al. were trying to orient the LM, but the RCS on the CSM was dead, so it felt like "...flying with a dead elephant on our back", only this time around, it's like two LIVE elephants trying to decide who is the elephant with orientation priority.

I don't know if this makes sense, but my point in this post is, I wonder if Squad can find a way to look into that, and perhaps NOT allow the RCS to function as one unit BEFORE the two craft have hard docked. It's not a show stopper, but it does waste RCS fuel, if you don't realize that it's happening and you wonder why the two spacecraft are "struggling" to hard dock.

[Brabbit1987]

I find a good solution for this would be to count even docked ships as separate, meaning it still has it's own controls and can be switched to like a separate ship. Then when you want to truly combine them, you can right click on the command module and click "Hard Dock" which would combine all controls. Who knows this could even fix some of those explosive docking issues, if they still happen in .20.

[rodion_herrera]

UPDATE:

*slaps forehead* I forgot to factor in one important detail--to keep orientation, I usually have SAS/ASAS on too, while also having RCS on. Which probably means, that the two RCS systems are NOT really connected magically--perhaps it's just RCS trying to "fight" the effect of the magnets (and on top of all that, ASAS also trying to keep things "in line") on the docking rings. So I think it's just another "chore" that someone has to attend to, and doesn't have enough merit as an issue for devs to be concerned with. But still, I want to know you insights on this phenomenon, and how best to solve/fix/improve on the techniques involved/related with it, if only for planning fuel efficiency during flights/missions. I say "fuel efficiency" mostly as an RCS issue--at one point during an "EOR-type" Mun mission, I left my two spacecraft struggling to dock with each other (ALT-tabbed back to Win desktop), and when I checked on both again, they were indeed hard docked, but RCS on both ships were depleted (probably due to the struggle).

Edited May 24, 2013 by rodion_herrera

[Splode]

This isn't a bug, there is no reason to have rcs turned on on the ship you're not controlling

[rodion_herrera]

This isn't a bug, there is no reason to have rcs turned on on the ship you're not controlling

I didn't imply that it was a bug, but something that perhaps could be "enhanced" or improved, and brabbit's post above (thanks! I like that idea!) signifies the sort of posts I look for, when I started this thead--I took back part of that request in my second post above. So please, for the others, this is not a bug-hunt--it's a brainstorm session.

And actually, there is a reason why one would want RCS to be on, on the other inactive ship, esp. if THAT ship doesn't have a good RCS layout in terms of CoG...say while docking, you accidentally bump that other ship...now if that other ship doesn't have RCS or ASAS on, it will start to spin/rotate in one, two or three axes, which will be a nightmare for re-orienting your docking approach. But if RCS plus ASAS is on, bump into a ship, no problem--it remains stable and won't spin. You might then say "But if your ASAS is on, on the other ship, then ASAS can deal with the spin..., yes, but only on LIGHT ships with good RCS layout considering CoG--on large ships with not-so-good RCS layout, ASAS will have difficulty stopping the spin in time.

Edited May 24, 2013 by rodion_herrera

[Evil Acrylic]

I used to have this problem before i started docking differently, As you pointed out its not the RCS causing this issues it is the ASAS trying to keep both the ships on the plane that you set it and you can get some epic wobble on the go lol

The quicker way is to get to about 50 - 75 meters away then stop your approach then switch ships then turn the docking port so it is aligned to your docking ship then turn SAS on then back off once its stop turning, then switch back to your docking ship and you have a streight line to dock at when you dock nether ship would need to have SAS turned on.

Its actually stress free and much quicker

Edit: Spelling :-(

Edited May 24, 2013 by Evil Acrylic

[rodion_herrera]

I used to have this problem before i started docking differently, As you pointed out its not the RCS causing this issues it is the ASAS trying to keep both the ships on the plane that you set it and you can get some epic wobble on the go lol

The quicker way is to get to about 50 - 75 meters away then stop your approach then switch ships then turn the docking port so it is aligned to your docking ship then turn SAS on then back off once its stop turning, then switch back to your docking ship and you have a streight line to dock at when you dock nether ship would need to have SAS turned on.

Its actually stress free and much quicker

Edit: Spelling :-(

Now that sounds like a nice, stress free plan indeed I guess it's just a matter of writing the checklist Thanks!

[superm18]

one word...WLAN

[karolus10]

I would like to see action groups assigned to specific command module... this would allow to had multiple modules/spacecrafts docked together with separate set of commands (for example lander module can had different abort sequence/ RCS groups than launch vehicle).

Also pods action groups could possibly interface with each other using actions aliases (name of action group, not key assigned to it), so we could trigger other action groups with same name (if action in selected module will had global status, otherwise we must control from specific command module) or prioritize other action to use instead (specified by name) if available.

For example we could use action groups on docked ship command module like it never docked and disable/enable solar panels, propulsion or thrusters assigned to groups. It can provide some order and preserve ship actions if ship undo-ck or module get relocated.

Other useful feature would be "control channels" could assign control surfaces/gimbals/torque devices to specific rotation/translation movement, ie. thruster "ABC" could be set to be used only to control roll axis (like strong RCS for rolling large gimbaled rocket) or specific translation movements.

Edited May 24, 2013 by karolus10

[rodion_herrera]

I would like to see action groups assigned to specific command module... this would allow to had multiple modules/spacecrafts docked together with separate set of commands (for example lander module can had different abort sequence/ RCS groups than launch vehicle).

Also pods action groups could possibly interface with each other using actions aliases (name of action group, not key assigned to it), so we could trigger other action groups with same name (if action in selected module will had global status, otherwise we must control from specific command module) or prioritize other action to use instead (specified by name) if available.

Other useful feature would be "control channels" could assign control surfaces/gimbals/torque devices to specific rotation/translation movement, ie. thruster "ABC" could be set to be used only to control roll axis (like strong RCS for rolling large gimbaled rocket) or specific translation movements.

I'm glad I'm not alone in wishing for features like this. The specific-axis locking would be especially useful, along with RCS-always-on option--sometimes, you can use purely RCS (if you have tons of it hehehe) for raising/lowering apoapsis or periapsis on low-grav places like Minmus, so it would be useful to set RCS forward/backward translation to like a toggle instead of having to have the "H" key pressed down.

[karolus10]

Action groups separate for each command pod would be more powerful than just managing RCS, especially if action/ groups would get increased capabilities.

One ship can had multiple command modules on-board for different purposes (launch vehicle, orbiter, lander, rover, probes) so every of them could had different commands.

Also this made keeping order (like mentioned RCS groups or undocking command for specific docking port) on larger ships easier or reuse some craft/stage/rover etc. as sub-assembly with their action groups set included.

EDIT_1: Soft/Hard docking is over-complicating things, especially that we don't had soft impact docking and ships after merging are one ship.

Edited May 24, 2013 by karolus10

[Ells]

If you "disable crossfeed" or is that just an option once docked?

I found it best not to have RCS on the ship trying to dock to as it really fights with larger space station sections and wobble.

If I bump the main ship, then i back away, hold, switch, re-align main ship and move in again.

In the past I have sent big space station sections rotating out of control and fought for minutes to re-gain that control, the old "dead elephant" syndrome.

Now my docking is much much slower with carefully placed RCS ports.

My next challenge is to dock a ship that has the collar on the underside..actually why am I typing here and not doing that....