Time Compression question

Blacklight

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This is just something I'm curious about and I didn't see it mentioned in the Orbiter manual.
When cranking up the time acceleration for long planetary journeys, my spacecraft which was oriented properly on it's direction of travel with the engines off begins to go into a violent spin that seems to accelerate over time. My question is this:

Is this due to 1. the simulation engine's math breaking down because my processor can't handle all the calculations per second it needs to, or 2. are there gravitational forces at work that are putting the craft into a spin ,that's effect is too small to be noticed in low time acceleration, but builds up over time ?

If I let it go, the spacecraft can become a blur, even when i jump back to real time.
 

DaveS

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Make sure that no attitude autopilots are on when engaging time acceleration. Or that you for that matter make any commands to alter the attitude during time acceleration!

It's simply because everything is magnified by the time acceleration factor, like attitude commands.
 

TSPenguin

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Orbiter works in time steps. The slower your processor the more time each time step has to cover.
When you use time acceleration the same applies. If you press the any thruster key for a tenth of a second then orbiter executes this over (let's say) 50 time steps. At 10x it does this for 5 time steps. At 100x the key press lasts for orbiter 0.5 time steps, but orbiter will only see that during that time step your key was pressed and executes the command for one time step and the burn lasts double that long. At 1000x this means that you burn your engines for 2 seconds instead of 0.1 second. Include some more detailed inner workings and you get completely uncontrollable spins.
All of this is true for autopilots too, so make sure to deactivate all of them before going to time acceleration. There is even a mod that disables all default auto pilots automaticaly.

That beeing said, a constant spin under high time acceleration is quite normal. The included killrot never really kills your rotation, it only reduces them. This can be observed really well when looking in the scenario editor. If you return to normal time your ship will seem motionless again. Absolute Killrot is an addon which will actualy null your rotation.

Happy Orbiting
 

Blacklight

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The odd thing is that this accelerated spin occurs when there are no thrusters firing at all. I always fire my thrusters in real time, cancel out the spin and then boost up the time compression. I never fire ANY thrusters or maneuvering jets with time compression on.

This means that my craft actually is rotating (and its rotation is accelerating for some reason) but so slowly that I don't notice it in real time ? The craft always ends up in the same violent blur of a spin after jumping back to real time (once again.. no maneuvering thrusters were used when the time compression was high and rotation was killed prior to increasing the time compression).
 

TSPenguin

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How did you kill your rotation? Via Killrot or with the scenario editor?
Try the latter one and see if the same thing occurs.
 

Kveldulf

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I've noticed this before. What happens is when you use Killrot, it doesnt kill all your rotation. You are still rotating, although only at about 0.0001 m/s or so. To fix this, along with your "high-speed" rotation, open up the built-in scenario, and click edit on your ship. There should be an option for Angular Velocity. All you do is click on that, then click kill.

If you dont want to use the scenario editor, there's nothing you can do I think.
 

-Pv-

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"There is even a mod that disables all default auto pilots automaticaly."

Orbiter Sound config program has a checkbox to disable autopilots when 100X or more is used.
-Pv-
 

ktaggart

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Killing Rotation

There is an addon that properly kills rotation:
AbsoluteKillrot v.1.2
[ame="http://www.orbithangar.com/searchid.php?ID=2899"]AbsoluteKillrot v.1.2[/ame]
 

Spike Spiegel

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Hi there. I had the same issue and I seem to have resolved it, so I thought I'd post my solution.

I've used AbsoluteKillRot version 1.2, and after that failed to fix the problem, I used the built in scenario editor to kill my rotation in the manner described here. Neither worked to prevent the "spin of doom" from occurring again. They certainly worked to kill my rotation once time acceleration was normal, but as soon as I would accelerate past 100x or so, the spin began again.

What I also noticed was that I gradually lost fuel. In the case of the Delta Glider I lost RCS fuel, and with vessels like Deepstar I just lost normal fuel, since that's all there is. This led me to believe that perhaps something was firing slightly, even though I had switched off RCS and all throttles were at zero.

Then I tried deactivating the Fly-By-Wire module version 0.9 beta ([ame="http://www.orbithangar.com/searchid.php?ID=3223"]Fly-By-Wire 0.9 beta[/ame]). It's got the most excellent configuration system I've ever seen for a joystick/controller, allowing for great customization. I had been using it with my XBox controller (original, not 360). As much as I enjoyed Fly-By-Wire, deactivating it has apparently fixed the "spin of doom" problem. No more unexplained fuel loss either.

Can someone advise me whether I should submit a bug report on Orbit Hangar's Fly-By-Wire page, or should I attempt to contact the developer directly? Also, has anyone else found this problem and can they confirm whether Fly-By-Wire was the cause? It seems to have worked for me, but to be scientific about it, it helps if the results can be duplicated. For all I know, it could have been the controller or its 3rd-party driver.
 

Hielor

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Hi there. I had the same issue and I seem to have resolved it, so I thought I'd post my solution.

I've used AbsoluteKillRot version 1.2, and after that failed to fix the problem, I used the built in scenario editor to kill my rotation in the manner described here. Neither worked to prevent the "spin of doom" from occurring again. They certainly worked to kill my rotation once time acceleration was normal, but as soon as I would accelerate past 100x or so, the spin began again.

What I also noticed was that I gradually lost fuel. In the case of the Delta Glider I lost RCS fuel, and with vessels like Deepstar I just lost normal fuel, since that's all there is. This led me to believe that perhaps something was firing slightly, even though I had switched off RCS and all throttles were at zero.

Then I tried deactivating the Fly-By-Wire module version 0.9 beta (http://www.orbithangar.com/searchid.php?ID=3223). It's got the most excellent configuration system I've ever seen for a joystick/controller, allowing for great customization. I had been using it with my XBox controller (original, not 360). As much as I enjoyed Fly-By-Wire, deactivating it has apparently fixed the "spin of doom" problem. No more unexplained fuel loss either.

Can someone advise me whether I should submit a bug report on Orbit Hangar's Fly-By-Wire page, or should I attempt to contact the developer directly? Also, has anyone else found this problem and can they confirm whether Fly-By-Wire was the cause? It seems to have worked for me, but to be scientific about it, it helps if the results can be duplicated. For all I know, it could have been the controller or its 3rd-party driver.

Have you tried setting a lower deadzone at the bottom end of all of your control axes?
 
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