[Solved] Align CoT and CoM

[PrimoDev]

Hey !

I'm working on a funny realistic satellite (I know it's not really useful in the game but hey, let me design whatever I want) and I just had a problem :

I need a little bit of thrust to finish their orbit in case of keo-stationary orbit and so I need to align the Center of Thrust (CoT) and the Center of Mass (CoM) but ksp tool isn't precise enough..

So I was wondering if someone know a way to be more precise like a mod (in 1.3.1 please) or anything that could help me in these situation.

By the way, I'm not looking for reaction wheels to compensate as it's supposed to be like in the real life

Edited December 26, 2017 by PrimoDev

[Laie]

@linuxgurugamer is maintaining RCS build aid and has working versions on his github.

AFAIK there's issues with some kinds of non-stock propulsion (properllers and the likes), but for ordinary jets and rockets it works nicely. Should keep you covered. Do not expect that you can get 100% perfect alignment, though.

 

45 minutes ago, PrimoDev said:

By the way, I'm not looking for reaction wheels to compensate as it's supposed to be like in the real life

Be aware that "RCS only" for attitude control  doesn't work all that well in KSP. Maybe you could make something work with persistent rotation and writing your own control scripts, but the usual PID controllers (SAS, Mechjeb, kOS cooked controls) work much better if you have at least a tiny amount of magic torque (like, a 0.5kN probe core for a 10t vessel).

[PrimoDev]

 

16 minutes ago, Laie said:

@linuxgurugamer is maintaining RCS build aid and has working versions on his github.

Okay that's great news ! I will try RCS build aid it might help.

16 minutes ago, Laie said:

AFAIK there's issues with some kinds of non-stock propulsion

I'm not using any engines coming from any mod

17 minutes ago, Laie said:

Be aware that "RCS only" for attitude control  doesn't work all that well in KSP.

I was not thinking of attitude control but just change a bit my orbit once the sat is deployed and as there are heavy things only on 1 side of the sat, I need to adjust CoT.

But no way of setting like instead of big fat indicator of CoT and CoM something very precise like just a little line for CoT and a precise 3D cross for CoM ?

[Laie]

40 minutes ago, PrimoDev said:

I was not thinking of attitude control but just change a bit my orbit once the sat is deployed and as there are heavy things only on 1 side of the sat, I need to adjust CoT.

Yeah, RCS build aid is the go-to mod for that kind of problem. Don't worry too much about the arrows: just note the figure for torque in it's window, and try to shift your engine (or payload) to reduce that number. As you do so, you will also notice how the arrows change, and start to understand what they mean.

Coming to think of it, KER has a "thrust torque" display as well. Using that and some common sense should get you there as well.

51 minutes ago, PrimoDev said:

But no way of setting like instead of big fat indicator of CoT and CoM something very precise like just a little line for CoT and a precise 3D cross for CoM ?

RCS build aid allows you to scale the indicators. This solves the problem that a small probe may entirely vanish inside the indicator balls. However, the point and arrow indicators leave much to be desired regardless of their size. If you want serious precision, read the figures.

[PrimoDev]

Great I just tested it and it work as I wanted !

Thanks for explaining ! I now have a question :

CoM is Center of Mass but what is ACoM and DCoM in RCS Build Aid ?

[Laie]

Average and Depleted CoM, that is, tanks half-full or empty.

[PrimoDev]

Thanks for all of this informations

[Rocket In My Pocket]

Nervermind lol, thought we were talking about something else! Lol.

Edited December 26, 2017 by Rocket In My Pocket

[Vanamonde]

This question about how to play the game has been moved to Gameplay Questions.