Aquila instability with small craft docked to it.

David Schmidt shared this bug 20 days ago
Submitted

After completing a mission I docked the small fighter to a connector I created on top of the Aquila (see picture). Aquila is 250 t, small craft is 16 t. The small craft is completely powered down (confirmed in the control panel with all blocks showing red bar).


Simply rotating the Aquila using the mouse (gyroscope) side jets all fire and move the ship significantly sideways with a high fuel use. Even when controls are left idle the H2 level in the Aquila is going down and simply turning the ship uses up a lot of H2.


Simply turning a ship with gyroscopes shouldn't fire jets at all (even with dampeners on) and an off-center mass may cause a change in center of gravity around which the ship rotates the ship should not make significant movement changes.


To repeat: simply dock a small craft to the Aquila. Turn off power to the small craft. Then simply turn the Aquila with the mouse with dampeners on.

Replies (5)

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1

I have this too and I have spent several hours trying to figure out why it is doing this. Things I checked, orientation of the gyro, orientation of the survival kit, rebuilt the connectors. Checked all settings, turned off target based gyro which didnt change anything. Im not sure what else to do. I have checked other ships as well and also used different ships to attach to Aquila. Everything else works as expected. Something in Aquila is bugged.

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1

It's hard to transport smaller ships in general at SE2.

I'm doing Every time:

1) small ship is pulling big one in direction where it really located, so perfect location of small ship is behind or inside the big one (not at a side)

2) every time before starting - turn off Gyro and Engines of small ship

Rare exception if you are pulling the big Renegade ship - it is more stable with Gyro turned on at both (but will be harder to turn)

3) transfer ALL cargo from small ship to big one, the total weight really matters

4) and the last but important - big one should be Much heavier than small one by weight, not by size - Aquila is empty and not heavy

I think you should have 10-15 small Gyro on Aquila for comfortable flight with small ship, you can disable some Gyros when small will fly away.


The situation which you describe about firing Engines at attempt a turn - it's correct.

Lightweight Aquila is counting a "small" ship as an anchor - trying to turn, by weight logic, Aquila is moving around an anchor - engines are trying to compensate that movement. So it's not using engines to fly, it's using engines to stop your turn.

Same time - position of small ship is 100% wrong, it's an anchor at the side of a ship.

Even with exactly the same weights and power, if you will locate small ship perfectly behind the Aquila (where the rear engine by default) - it will act differently.

Or ignore location and weight and build 30 small Gyros at Aquila - they will compensate rotation around anchor, and engines will be relaxed.

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1

I've found that moving any ship with any connector-docked ships highly difficult. There are several failure modes including one where the ship will accelerate and be stable to 400-500kmh then suddenly flip into a vertical loop and come to a rapid halt. The fix for me was to only use landing gear to attach ships to each other for flight. I built a huge space station to take all my ships between systems and attached several massive ships to this and it never failed.


However, in survival, I built a large multi-purpose ship in the previous release - it worked perfectly and I blueprinted it. I've now managed to rebuild it, from the blueprint, in the current version of the game and it's not turning properly. It has nothing docked. If, say, I'm in space and not moving and ask it to rotate right on its axis, it moves forward and right and the engines fire up to try to stabilise it - it moves in some very unnatural-feeling arc and rotating back reverses the effect. I crashed into the Verdure space station thanks to that one. I think something weird is now happening with how mass reacts to gyros.

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2

I have this same bug in space and in my head this should not happen in space where there is no gravity. I could see this or something similar happening on the planet in gravity though. Again, it doesn't feel right that this is the behavior in a zero gravity environment.

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It's not about gravity or 0 gravity, it's more about Newton's law - if you pull it, it pulls you back in the direction of where it is attached. Same time it could be even more notisable in space, while there are no other forces which can compensate the force of small ship pulling you back.

Just watch a movies like "Gravity" - there are a lot of moments in space where even a small forces start extremely turning, pulling the actors or their ships flying in space.

Desctiption of This movie in wikipedia:

1. Since the impacts do not strike the center of mass of the stations but rather hit tangentially, the structures are instantly sent spinning along all axes.

2. Absence of air resistance: In the vacuum of space, there is no atmosphere to slow down or stabilize rotation through friction. Any rotational momentum gained is conserved, causing the modules to spin indefinitely until acted upon by another external force.

In case of SE2 - Engines are trying to stop the turn ;) Or you should use a lot of Gyros at main ship.

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3

While I understand the physics of thrust that isn't applied through the center of mass, the magnitude of the reaction seems excessive. One possible reason for this is that thrusters are either ON or OFF, with no partial thrust. Because of that a small off-axis thrust ends up creating a much more severe reaction as ALL engines used to counter the motion go to full thrust.


This seems to be an over-reaction from the dampeners related to direction changes. I can fly with an off-center mass attached just fine with dampeners on as long as I don't change directions at all. I can go forward/backward/left/right/up/down and ship doesn't turn at all (even with off-center mass) but simply turn on dampeners and the ship makes extreme corrections.


In addition, when in space when ship is at 0 relative motion simply turning the ship with gyros creates the same excessive reactions while turning off dampeners makes the ship move as if nothing is attached. I'm able to carry smaller craft by turning the ship with dampeners off and then turning dampeners ON and moving with just thrusters.


I like that there should be some effect from off-center thrust, but the current effects don't feel realistic at all.


Lastly, we can't claim that the physics are at all realistic when ships don't change heading even with thrusters not centered around the center of mass. Look at the Aquila (new survival game starting ship) and it's upward facing thrusters. In space, if I move the ship "down" using the 'C' key I should see ship rotation (nose up). Ship's gyroscope could be countering that off-center thrust, but then the ship's gyroscope *should* be doing the same when a new mass is added.

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4

It's not just thrust either.

You can 'turn' your ship with no thrusters and only a gyro.


These phantom forces are still there. And they're extreme. If you 'turn quickly' and have docked ships you can end up strafing a direction at speeds in excess of 80 m\s.

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2

I don't understand why there aren't more topics complaining about this right now. My own report slid down to page 25 or something. This issue is not specific to any one ship, but every two docked dynamic grids. It's rather game-breaking at the moment but no hotfix in sight and the Bug-tracker here is busy with ever repeating complaints about all the buggy contracts ;(

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2

Did you try telling the connector of the big ship that that connector is not a parking connector (from its POV)? I'm not sure if that's related or it's just to not disconnect that when unparking from a base. I had the same trouble before but now I'm carrying a medium ship and it's easier I think. The child ship is on top of Aquila and aligned and I have 2 big gyros on Aquila. Maybe that's it.

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2

No, it has nothing to do with the connector on park or not. As you said, this is to stop it from disconnecting when you dock the mothership to a base or something. I've tried with several ships of all sizes in 2 different saves and whenever something is docked on or in a larger ship, the larger ships thruster fire when you try to steer it, which shouldn't happen. There is no mass-compensating thruster-activity in space engineers. It's simply the dampeners bugging around because sub-grid/docked-grid calculation is broken. One of my ships weighs just over 4500 tons with equal crazy amounts of gyro power and it freaks out when i dock a small drill-ship of about 30 tons to it. No even remotely sane physics-simulation would cause this behaviour.

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