Satellite out of control because of tracking solar panels

[THX1138]

Here's a satellite I have. You can't tell because it's a screenshot but it's actually spinning around and around. I can't stop it because there's no power to use the reaction wheel. The solar panels are deployed and in direct sunlight but they use all the power the get trying to track the sun and their constant tracking seems to be causing the damn satellite to keep spinning around and around. I can't swtich to another craft because this one is "under acceleration". Previously I've recovered from this situation by holding the buttons (W, A, S, or D) as necessary to counter the spin and waiting for it to slowly stop at which point the panels function properly and the battery begins to charge. Would you call this a bug? It's a pretty stupid situation and if the damn panels would just stop tracking and wait for a moment, I'd collect enough light to power the reaction wheels but there's no such option to ever stop them tracking. They're not fit for purpose, I'd say.

[RainDreamer]

Pretty sure you can right click a solar panel and disable sun tracking...or is that not in stock? I have been playing with mods for so long.

[THX1138]

The only option (for this panel at least) is to retract the panels but even that isn't available without power in the battery, not that I'd want to use it. I made a quicksave and then reloaded that quick save which stopped the thing spinning. The panels are still flawed IMO, at least in stock KSP.

[sal_vager]

Sun tracking does not use power though, the only thing on there that I can see that would use your power is the Ion drive, but your throttle looks like it's at zero.

Make sure it is by pressing X though.

[Claw]

If you can, upload the save file.

It's helpful if you delete all the other flights, just make sure you make a backup copy before you do that! Or at least state which craft it is so we can find it.

Cheers,

~Claw

[THX1138]

I didn't delete the other craft because there are so many and you have to do each one by one. I actually have about 10 of these identical satellites but you could use the one called "Satellite, destination: Eelo", for example. It's easy to recreate the problem. Just apply full thrust and leave it like that until the power runs out. Then you'll have a satellite spinning out of control. The thrust automatically drops to zero. If the tracking does indeed not use power (not very realistic!) then maybe the small bursts of exposure are insufficient to cover the baseline load of the Probodobodyne HECS. I think the tracking of the panels overwhelms the SAS even though the reaction wheel is plenty powerful enough to manually control the orientation manually.

http://www.filedropper.com/spinningsatellitetroubleshoot1

[UmbralRaptor]

Despite the throttle setting, the xenon consumption is consistent with the ion engine running at full. Testing with the save file shows that the engine is still burning fuel regardless of throttle setting, which I suspect is why there's the lack of power. The spinning out is caused by the center of mass and center of thrust not lining up, requiring active corrections from the reaction wheels.

This is seeming like an engine/control bug.

edit: try continuing to press throttle down while it's already at a minimum from x?

Edited January 4, 2015 by UmbralRaptor

[sal_vager]

Seems to be working for me, throttle is zero and it's charging normally, I can exit to the space center so it's not the save.

Could this be another Windows x64 bug?

[UmbralRaptor]

Could this be another Windows x64 bug?

Not exactly. I was able to reproduce it with 32bit windows.

[Lhathron the Elf]

I think one thing that nobody has mentioned is simply turning on SAS. It appears in the screenshot that SAS is turned off, and I think simply turning it on will get the probe to stop itself from spinning.

Just going with the obvious answer here, since everyone seems to be straying away from sense and towards rocket science.

[sal_vager]

Okay, not reproducible in 32bit Linux, the satellites load up not-tumbling, they recharge, throttle is off, xenon is not being consumed, SAS is functioning, everything seems fine.

Oh dear, Lhathron is right but I assumed THX1138 tried that.

I can't stop it because there's no power to use the reaction wheel.

[THX1138]

You can't turn SAS on. SAS turns off because there's no power. Also, loading the save won't precipitate the bug. You have to drain the battery (e.g. by applying full thrust) first.

[sal_vager]

Ahh yes I see it now, the probe dies with the Ion drive still on and X is not enough to stop it.

But I have found a workaround, you can still right click the Xenon tanks and stop the flow, this stops the drive and your probe recharges.

Setting the thrust limiter to zero can also do it but is less reliable, it took time and mashing WASD for the engine to stop drawing electric charge this way.

Edited January 4, 2015 by sal_vager

[THX1138]

So the force comes from the engine, not the rotating solar panels? Would you still say this is a bug? I'm not sure... maybe there are situations where you'd want thrust to stay on when power runs out (using liquid fuel engines).

[Technical Ben]

I suppose it's doing a "out of control" as it looses power to the core (control unit! ).

Making it clear control was lost would help, as it would at least show it's a "lost probe" in most instances. However a better way for the game to respond would be to kill the engine first, then the core. That way the solar panels would bring the core back to life and you could decide if it's best to turn the engine back on.

Currently, instead the engine comes on first, and then kills the core almost before we have time to turn the engine back off. If I've read the details correctly.

[Dr-Drunk]

I can confirm that this is a problem with no power flowing to the command module when the engine is in use. Basically your ion drive is using up so much power that it shuts down your probe wich in turn means that you can't tell the probe to turn the engine off. Once that happens ... well ... you've lost all control of the probe I geuss.

As Sal said though, you can turn the Xenon gass off wich seems to allow the probe to recharge again. I've had this exact thing happening with the first set of satellites I sent to Minmus. They were of a kinda shoddy design and didn't carry nearly enough battery packs to sustain running on an ion drive. I had to run them at 2 second thrust intervals to prevent them from losing control.

So yea ... My advice would be add more batteries for long maneuvers or add more solar power or radio isotope generators to offset the use of the ion drive.

[sal_vager]

So the force comes from the engine, not the rotating solar panels? Would you still say this is a bug? I'm not sure... maybe there are situations where you'd want thrust to stay on when power runs out (using liquid fuel engines).

It's a definite bug that the Ion drive won't shut down with X and return control to the player, your rotation is due to an imbalanced craft with no SAS when the batteries die.

[THX1138]

I don't want to add more batteries because that will reduce the range of my satellites. I'll just try to remember not to use full thrust.

[Technical Ben]

(Batts are physicsless, well side mounted anyhow AFAIK, so range should be the same. However, the main problem is the number of solar panels, 5 is required, 6 is balanced for full throttle.)

[sal_vager]

Just cut the drive before your batteries go flat

[THX1138]

The work around to this bug seems to beget another bug! After cutting the flow of xenon the batteries start charging which is good. What's not so good is that SAS is now broken. I can turn the SAS light on and off but the little options (regular SAS, prograde, retrograde) don't appear and SAS is completely ineffective. The reaction wheel responds to manual control. Switching to another craft and back again fixes it.

Edited January 7, 2015 by THX1138

[Captain Sierra]

The work around to this bug seems to beget another bug! After cutting the flow of xenon the batteries start charging which is good. What's not so good is that SAS is now broken. I can turn the SAS light on and off but the little options (regular SAS, prograde, retrograde) don't appear and SAS is completely ineffective. The reaction wheel responds to manual control. Switching to another craft and back again fixes it.

1) SAS is not perfect and will not hold a heading rock solid. 2) probe cores have very little SAS. The craft is imbalanced due to the solar panel layout and the ion has enough thrust against that low mass to cause more torque than the SAS can counter.

It's a definite bug that the Ion drive won't shut down with X and return control to the player, your rotation is due to an imbalanced craft with no SAS when the batteries die.

I'm inclined to disagree. The stock game handling of probes is that they need power. When an ion engine or other power source hogs all of it, the probe core can no longer function. That seems to me like user error combined with an unforgiving game mechanic, which can and maybe should be changed, but I see no reason to consider that a bug. Just my .02.