How do I stop spinning?

[Trekkin]

I\'m trying to fly a relatively large rocket around in Kerbolar orbit, and every time I go faster than about 10 km/s, my ship becomes uncontrollable. It just starts flipping end over end, even with all engines off, and the reaction wheels in the pod just spin it around its y axis. Mechjeb also just starts it flipping, although after about half an hour it stops--off target. The bizarre thing is that it never wants to move in just one axis, but rather in all three simultaneously, in space without any external forces acting on it at all.

[semininja]

There are a few old threads about this, which can be found with a search for 'Deep Space Kraken'. It\'s mostly a problem with the physics engine, unfortunately, so there\'s not much that the developers can do.

[Trekkin]

Oh, this is the kraken? I thought the kraken involved ships being destroyed.

[Accelerando]

The Kraken is an error with the PhysX engine that IIRC causes errors in numerical rounding above ~9000m/s (it varies with rocket size, larger assemblies usually encountering it at lower relative velocities). This leads to extra 'forces' which cause your ship to spin out of control or otherwise go off-course in some way. I may be wrong, though.

http://kspwiki.nexisonline.net/wiki/Deep_Space_Kraken

[Trekkin]

Well, how have people done solar flybys and the like, then?

[Accelerando]

Well, how have people done solar flybys and the like, then?

Tiny spaceships.

It is possible to survive a solar flyby even with ghost forces, and generally if you\'re not getting too close — which, again if I recall correctly, is any point below a distance of something like 1.5 million kilometers in a stable orbit — to Kerbol your ship won\'t be ripped apart (although it may spin uncontrollably regardless of size).

[thorfinn]

so there\'s not much that the developers can do.

There\'s a lot that they can do, they just haven\'t gotten around doing it yet because there are no other planets for the time being.

They must fix it, it\'s an absolutely vital part of the program... they already have a plan^*, actually, it will be implemented in the update that brings in other planets.

* IIRC, they will move the floating origin system into the phase space.

[duckunlimited2]

You can stop your ship from spinning by time warping till your ship is on rails then exit out. That should solve your spinning problem. However, If your trying to burn and accelerate, that option just won\'t do now would it. I\'ve successfully navigated the interstellar space between Kerbin and Kerbol with a space vessel that weighed more than 40 kerbal mass units, however the design was extremely simple (everything stacked end to end like a rocket), which helped fend-off the space kraken. An extremely simple design wasn\'t all that kept the beast away. I had a very powerful gimbal engine and 8 radiating gimball engines boosters that shoot outward, a surprisingly small, but decent amount of SAS power with ASAS of course., and RCS thrusters. I believe the time it was most vulnerable to the space kraken is when I had to burn the engines, once I got it in and out of rails to get it stationary it was fine. I could spin it around too with a little squirt of RCS.

Well I wasn\'t in any extreme places like right next to kerbol or in an escape trajectory of kerbol but I think I have one of the biggest vessels to survive interstellar space.

Pics of the OASIS as I like to call it.

Okay, not a pic of OASIS, but you can see I am faster than the 9000m/s threshold, so I was in Kraken territory.

Here\'s OASIS. You can see how big, yet simple its design is. Believe it or not, but it\'s on a return trajectory to Kerbin after being in the orbit above. Kerbin and Mun is to the left of the engines. Yep, I gots mad rendezvous skillz. 8)

[Bluejayek]

ASAS/gimballed engines often dont help you. I find the kraken will mess upall your controls so that up makes you spin, left goes down, down spins AND makes you go left, and right does nothing (for example). ASAS cant cope wityh this.

[duckunlimited2]

Well, how do we explain how the OASIS was able to navigate through the lair of the space kraken relatively unscathed where similar sized space vehicles failed.

I actually have a more indepth theory on how the space kraken operates. Granted, I\'m no Unity expert but It makes a bit more sense. We all know that when we go faster then 9000m/s, our controls start to become unresponsive and phantom forces start acting on our ships. Its more pronounce on complicated ships with multiple parts then it is on simple ships with a few parts. Parts.....parts....... why is the number of parts on a ship related to the likely hood of phantom forces actingon your ship when going over 9000m/s. I then recalled an incident on a previous sun diving mission I conducted earlier. It was a very simple and light craft, designed with consideration that the space kraken still lurks in deep space. However, before I exited Kerbin\'s sphere of influence, and traveling way below 9000m/s, I turned off my ASAS, which was on the entire time from take off, and my ship started to spin and tumble uncontrollably. Any input on my part would just add to the problem. Apparently the spinning was the result of colliding parts on my ship. I fixed the problem by repositioning the colliding parts and problem solved. Funny how that incident acted as if the space kraken was clawing at my little ship. Could colliding parts be the root of the mysterious phantom forces and unresponsive controls? Well, lets say that when Unity is calculating something going faster than 9000m/s, it starts to lose some precision. For example, lets say two parts are both supposed to be calculated at going a speed of 10000m/s. However, Unity goofs because it has trouble calculating things going that fast and calculates one part going 10000m/s and the other part at 10001m/s. The parts are now going in different speeds. If they were connected, but going at different speeds, wouldn\'t some collisions start occurring between them and cause the same tumbling and spinning as seen as my sundiving vehicle? I bet money that it will. It also explains why a simple ship with a few parts are spared more frequently from the clutches of the Kraken then a bigger ships with more parts. It comes down to the fact, that more parts, means more errors and different velocities between the parts which results in more collision which equals more force. Little ships don\'t have that accumulative effect because there so simple and SAS is way overpowered on something that small then for a bigger ship. Also controls act funny because when you try to change the orientation of a ship, it only adds to more of the forces acting on the ship which means more collisions, etc, etc, you get my point.

OASIS is very simple in design, and where parts collide, so it doesn\'t get the full wrath of the kraken. It does need assistance from RCS, ASAS, and gimballed engines, but thanks to simple design, it survives.

Sorry for long post, here\'s an emoticon ;P

[thorfinn]

Well, lets say that when Unity is calculating something going faster than 9000m/s, it starts to lose some precision. For example, lets say two parts are both supposed to be calculated at going a speed of 10000m/s. However, Unity goofs because it has trouble calculating things going that fast and calculates one part going 10000m/s and the other part at 10001m/s. The parts are now going in different speeds. If they were connected, but going at different speeds, wouldn\'t some collisions start occurring between them and cause the same tumbling and spinning as seen as my sundiving vehicle? I bet money that it will. [...]

And you would not lose your money. You\'re right on the spot

And that\'s why using a 'floating' reference point in the six-dimensional space of positions and momenta, instead of just the normal 3D space, should solve the problem. (In practice, most of the ship\'s velocity will be 'offloaded' to its frame of reference, like most of its displacement already is)

[vexx32]

I take it it isn\'t exactly the most simple of fixes, though, is it? After all if it was merely trivial, we wouldn\'t have to deal with a game-breaker like that. I have a hunch it\'ll be a bit uglier than it sounds to sort out properly, but it\'s nice to know it isn\'t impossible to solve.

[dogon11]

The Kraken is an error with the PhysX engine that IIRC causes errors in numerical rounding above ~9000m/s (it varies with rocket size, larger assemblies usually encountering it at lower relative velocities). This leads to extra 'forces' which cause your ship to spin out of control or otherwise go off-course in some way. I may be wrong, though.

http://kspwiki.nexisonline.net/wiki/Deep_Space_Kraken

Does that explain why my solar space station lost one of it\'s four sid-mounted engines, making it impossible to control?

[Khrissetti]

The Kraken is the reason I gave up on my Sundiver missions, I couldn\'t be bothered fighting it every time I wanted to make the smallest plane change.