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Uncontrolled spin glitch

Scarecrow
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Scarecrow

Scarecrow

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I have only experienced this particular problem in 1.2 and I am not sure if it is a bug that has arrived in this particular patch, or whether one of the mods I have installed is causing it.  To be fair though, I don't run that many mods, and none that are different from any that I've run with previous versions of KSP

The glitch I am experiencing puts the ship in to an uncontrolled spin, that takes quite a while to settle down back to stable flight.  I first experienced it when my craft was crossing the SOI from Kerbin to Mun, and it happened more than once when doing that.  Whilst annoying, it is merely an inconvenience.  My latest experience of it though had my ship suddenly glitching in to uncontrolled spinning and rolling during the final phases of a Mun landing.  Being so close to the ground, it crashed before I could get it back under control.

I was just wondering if anyone has experienced anything similar, and if not I shall start uninstalling my mods to see which one could be possibly causing it.

The mods I am running, which are all the latest version to be compatible with KSP 1.2, are:

Kerbal Alarm Clock, Kerbal Joint Reinforcement, Landing Height, Hyperedit, NavyFish Docking Indicator, RCS Build Aid

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Vanamonde

Vanamonde

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Posted (edited)

There was a change made to drag lately. Blunt objects have more, while streamlined objects have less. Could this be the cause of your issue? What does the plane look like? Pics, please. 

Derp. Missed the part about it happening in vacuum. Nevermind. 

Edited by Vanamonde
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HvP

HvP

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1 hour ago, Scarecrow said:

My latest experience of it though had my ship suddenly glitching in to uncontrolled spinning and rolling during the final phases of a Mun landing.

Does it tend to happen as you come out of time warp? I've seen this problem reported while using Kerbal Joint Reinforcement. See if what's mentioned in this thread matches your circumstances.

One other possibility is that if you have SAS set to follow retrograde then the switch between orbital and surface orientations can cause a serious jump on descent. Although this usually happens higher up than you describe. Try running without KJR and see if it helps. I've found that it doesn't play well with clipped parts or craft using the stock "rigid attachment" options.

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LordFerret

LordFerret

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Posted

I don't think it's the same thing, but I've been experiencing roll issues with SAS/RCS. In particular, the vessel rolls back and forth endlessly, burning off RCS like mad. The only way I've found to counter it, is to turn SAS and RCS off, manually cancel the roll, and then add SAS then RCS back in (if I'm to be soon making a maneuver, else I leave just SAS on).

In the past there was an issue with SAS fighting itself, but I thought it was resolved. Maybe not?

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Tex_NL

Tex_NL

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7 minutes ago, The Aziz said:

...

I trust autostruts more now, they're far more stable than KJR

Autostruts are evil. They are the spawn of the devil.
I tried to shore up my wobbly space station with autostruts. The wobble only got worse. Turned out the wobble was actually caused by the autostruts. Only by removing all of them was I able to subdue the Kraken.

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The Aziz

The Aziz

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2 minutes ago, Tex_NL said:

Autostruts are evil. They are the spawn of the devil.
I tried to shore up my wobbly space station with autostruts. The wobble only got worse. Turned out the wobble was actually caused by the autostruts. Only by removing all of them was I able to subdue the Kraken.

On the other hand, my station joints as strong as never now. And I put autostruts mostly around docking ports.

So I guess it's own preferences anyway, same as difficulty.

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swjr-swis

swjr-swis

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13 hours ago, Vanamonde said:

There was a change made to drag lately. Blunt objects have more, while streamlined objects have less. Could this be the cause of your issue?

I don't think drag is related to the issue mentioned: there is no atmosphere at the Kerbin/Mun SoI transition, or when landing on the Mun.

The new SAS logic in 1.2.x, while definitely improved in some ways compared to before, still has some glitches to work out.

The worst is a new and very distinct tendency of the 'hold prograde' mode to start an intense and sometimes amplifying swing in pitch angle, that I've only been able to counter by quickly switching to Stabilize and manually pitching closer to prograde before switching to hold prograde again. I can avoid it to some degree by strongly limiting the pitch authority of control surfaces and/or reaction wheels, but then it limits maneuverability more than it should need to. This is a behaviour I had not seen before 1.2.x.

There is also still a spontaneous roll while holding prograde, but this is not new, this is a pre-existing problem. I've not seen a similar problem with yaw though.

@Scarecrow, when you say 'spin', around what axis do you mean?

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Scarecrow

Scarecrow

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Posted (edited)

Perhaps tumble would be a better definition than spin, as it seems to be rotating about all 3 axis.  It's definitely not drag related as I have seen it outside atmosphere.  Also, it's not related to SAS trying to follow retrograde or some other direction as for 99.9% of the time I have SAS set to steady.  The only time I change SAS to anything else is when I want to reorientate the ship prior to a manoeuvre.  As soon as the ship is pointing in the right direction, I set SAS back to steady.

I will uninstall my mods, and reintroduce them one at a time to see if I can determine if one of those is the cause.

Actually, thinking back, I have seen some glitchy bumps during launch, where the rocket takes a sudden deviation from the direction it was pointing, but I am guessing the aerodynamic force of the fins at the back of the rocket were sufficient to prevent the bump developing in to a full blown tumble.

 

Edited by Scarecrow
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Scarecrow

Scarecrow

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UPDATE

Well I was unable to replicate the tumbling during SOI change, but I did have an aircraft that would experience moments of being pitched out of control whilst being flown around the KSC.  Using this craft as my test bed, and based on suggestions above, the first mod I disabled was Kerbal Joint Reinforcement, and this seemed to cure the problem.  With it installed, my aircraft suffered a number of 'tumbles' in the space of a couple of minutes.  With KJR removed, I didn't experience a single one.  I feel this heavily indicates that KJR is the culprit.

Does anyone know how I can contact the modder for KJR to offer him this feedback?

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Maveriick

Maveriick

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Posted (edited)

I had exactly the same issue. Craft goes into an uncontrollable tumble at approx. 5km up, meaning a serious case of lithobraking! Happens on mun and minmus, haven't tried other bodies yet.

I also had it happen to me on take off, did you see this too?

I have KJR installed too, but with some further testing today I can't seem to replicate the issue. Have you guys got anything further?

 

EDIT: on testing another lander on minmus, the tumble happened on take off but not landing

Edited by Maveriick
Further Testing
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