mk1-3 command pod - RCS

[antipro]

hi,

https://www.dropbox.com/s/fca1ysfptghuubi/2018-08-26_00-39-22.mp4?dl=0
 

this video shows me approching ike.
I didn't equipped the ship with RV-105 thrusters, I'm trying to use the embedded RCS, so:
instead of use the H/N keys, I orient the vessel radially and using the linear docking mode with the A/D keys, I think, in theory I can move as if I had the prograde thusters.

In practical this "workaround" seems to work but I experience that behavior you see in the video:
when I'm in the normal view it works(the ship doesnt rotate), instead of, when I switch to the map view(as I have to see where to go), you can clearly see the ship rotates out of control.

and even if in the video you see that I didnt activate the Precision Control(CAPS LOCK), doesnt matter, is the same.

so, why the ship change behavior by changing view? in particular why the ship starts rotating?

Edited August 25, 2018 by antipro

[Zeiss Ikon]

The rotation of the Mk. 1-3 when using only its built-in RCS is simply due to the craft's thrust not pointing through the center of mass.  I noted this when I first installed 1.4 and launched a vessel with this pod -- the RCS jets on the command pod are apparently intended only to work alongside a set of quads (or at least thrusters) located aft, on the service module, and they're virtually useless for just the command pod (other than for roll).

This is more or less consistent with the Apollo spacecraft; after decoupling from the Service Module, they had very limited translation and no fore-aft translation at all, and only limited pitch and yaw.  What they did have was very good roll control, which was all the Apollo needed during reentry.  The off-center balance of the spacecraft allowed a certain amount of "glide" to control depth of penetration and crossrange, simply by rolling during reentry (the craft would 'glide" toward the heavy side, as the heat shield would tilt that direction and produce a lift force not parallel with the velocity vector).

Given you'll generally have a service module or partially used stage attached to the command pod until just before reentry, don't be afraid to put some RCS on that stage.

[AVaughan]

If I want to use rcs for translation (eg for docking), then I normally set the rcs to translation modes only, and use the command modules reaction wheel + SAS to control attitude.   Doing that I normally don't need rcs to be properly balanced.

[Sharpy]

7 hours ago, AVaughan said:

If I want to use rcs for translation (eg for docking), then I normally set the rcs to translation modes only, and use the command modules reaction wheel + SAS to control attitude.   Doing that I normally don't need rcs to be properly balanced.

Yeah. First thing to do: Show actuation toggles, Yaw, Pitch, Roll -> OFF, on every thruster available. Not only does keeping the orientation using SAS work, especially in 'precision control', with SAS on and rotation control through RCS active, monoprop is leaking like crazy.

[Tyko]

This can help a lot...

 

[Snark]

Moving to Gameplay Questions.

[MR L A]

7 hours ago, Sharpy said:

14 hours ago, AVaughan said:

If I want to use rcs for translation (eg for docking), then I normally set the rcs to translation modes only, and use the command modules reaction wheel + SAS to control attitude.   Doing that I normally don't need rcs to be properly balanced.

Yeah. First thing to do: Show actuation toggles, Yaw, Pitch, Roll -> OFF, on every thruster available. Not only does keeping the orientation using SAS work, especially in 'precision control', with SAS on and rotation control through RCS active, monoprop is leaking like crazy.

Wow. 2k hours in and I'd never thought of this. Currently hanging my head in shame!

Just goes to show there's always something new to lean with this game