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Disable timewarp rotation if under a certain threshold #2556

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rsparkyc opened this issue May 4, 2020 · 5 comments
Open

Disable timewarp rotation if under a certain threshold #2556

rsparkyc opened this issue May 4, 2020 · 5 comments

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@rsparkyc
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rsparkyc commented May 4, 2020

I have a craft with solar panels only on one side. When I had persistent rotation installed, it would provide some sort of station keeping upon entering timewarp if the vessel's rotation was very close to 0, thus keeping the solar panels pointed to the sun. However, because principia doesn't implement that, it causes my solar panels to me misaligned as soon as I enter timewarp. I know principia was never designed to include any sort of station keeping, but is there another option here?

@eggrobin
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eggrobin commented May 5, 2020

Yeah, this is somewhat unfortunate for your craft.

As you have noticed, this is a bit similar to the stationkeeping problem.
Principia introduces unrealistic constraints because of its lack of stationkeeping, meaning that you have an incentive to look for dynamically stable orbits where you may go for station-kept ones in real life (as an example, GEO is notoriously unstable except at two specific longitudes).

Similarly, the lack of attitude-keeping means that you have an incentive to design spin-stabilized craft (as part of the design process, remember to check that the rotation axis is stable, lest the Джанибеков effect make your craft tumble in an entertaining fashion).

It may be easier to devise some scheme for attitude-keeping than for stationkeeping, but this will certainly take a while (after all, we are still ironing out some bugs related to persistent rotation, see the ongoing thread in #2519).


As a quick and very dirty hack to save your current spacecraft, you can freeze its orientation (though you will lose its history and its flight plan) as follows:

  • using the cheat menu, hack gravity: this hides the active vessel from the eyes of Principia;
  • timewarp, which will have the stock rotation-freezing behaviour;
  • unhack gravity.

The vessel being discovered by Principia in timewarp, it is assumed to be nonrotating.

For future vessels, consider spin-stabilization.

In the more distant future we may do something about this issue, but again this requires a bit of design thinking (perhaps we could detect that SAS is on and the desired attitude is being kept well enough? morally we ought to drain some power or RCS fuel but that seems far trickier).

@rsparkyc
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rsparkyc commented May 5, 2020

Thanks for the tip - this was the exact sort of answer I was looking for. I do like your idea of having it spin stabilized. The ultimate plan for this vessel was a lunar impactor, so it's had a full life now. If you'd like to keep this ticket open for the idea of attitude-keeping, then I'm fine with that, otherwise feel free to close.

@tiancilliers
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Bumping this, especially this part

perhaps we could detect that SAS is on and the desired attitude is being kept well enough

Definitely an improvement that would make it so much more pleasant playing with Principia. Bonus points if you detect prograde/retrograde/manuevre lock and fix orientation to that in the selected frame of reference. So many times I have locked onto a heading and warped to start of a burn only for my craft to be pointing in the opposite direction.

@MuhsinFatih
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Any chance this could get implemented, or maybe toggled per vessel? I have RSS - RP1 - Principia and I'm struggling with primitive solar tech because I need a good sunlight angle but no matter how stable I get the ship it rotates.

Space craft IRL keep orientation using RCS thrusters or wheel. It'd be really nice if for example a small amount of RCS thruster fuel is used over time and the ship remains in same orientation through time warp and when focused on other craft. Easier to implement would be a feature toggle per vessel. Unrealistic in terms of fuel consumption but I'd take that over not being able to face the sun at all

@Clayell
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Clayell commented Nov 15, 2024

Any chance this could get implemented, or maybe toggled per vessel? I have RSS - RP1 - Principia and I'm struggling with primitive solar tech because I need a good sunlight angle but no matter how stable I get the ship it rotates.

Space craft IRL keep orientation using RCS thrusters or wheel. It'd be really nice if for example a small amount of RCS thruster fuel is used over time and the ship remains in same orientation through time warp and when focused on other craft. Easier to implement would be a feature toggle per vessel. Unrealistic in terms of fuel consumption but I'd take that over not being able to face the sun at all

test_account answered this well in the discord, and I'll leave their response here:

A non-issue because of how kerbalism works, Your vessel's orientation stays the same while it's unloaded for the purpose of calculating solar panel output
Slow rotation only happens when you're at the vessel and you can spin stabilize it to point to the sun during that (usually brief) time

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