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A bug in my ship design?


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Kerbal Space Program is a physics simulator. Just because you can put parts together in a certain way in the editor doesn't mean the design is viable once gravity kicks in ;)

Your vessel twists and bends because attachments are not entirely rigid. There is no gravity in the editor, but on the launchpad, there is a full 9.80665 m/s² pulling on each individual part. And if a part is heavy, but attached from the side, then it will sag a bit as that attachment point flexes.

The strength of joints is proportional to the part's size. Their "bulkheadProfile" in the config file specifically, if I remember things right (but don't quote me on this, it's been quite a while since I last looked into it). Small parts with small profiles have very weak joints. You happen to have used very small parts on a very long lever arm to attach wheels to a heavy rover. The result is that the mass of the rover easily bends the weak joints of the small parts used to attach the wheels.

Now, depending on the destination of your rover, it may still be fine. Minmus for example has incredibly low gravity - just 5% that of Kerbin.

To test this, hit Alt+F12, go to the Cheats section, and find the "hack gravity" slider. Activate the checkbox and set the slider to 5%. You are now simulating Minmus' gravity. Look at your rover on the launchpad, and see if it still bends out of shape. If not, you'll probably be fine.

I say "probably" because gravity isn't the only enemy of flimsy construction. Inertia is, too. If you drive at a high speed on a flat surface that suddenly begins to slope upwards steeply, then your rover's front wheels are pushed upwards hard. The inertia of your rover's center section, however, will resist that upwards motion for a split second, because the wheel joints will flex first. This can result in your center section impacting the slope your are trying to drive on, damaging or destroying your rover. So, better test driving around the KSC, too, and hitting some of those slopes at the side of the runway, or the ramp up to the launchpad, at full speed.

 

Edited by Streetwind
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Do not be offended but did anyone really see the images I passed? gravity does not make sense, as far as I know gravity pulls down, but the image shows that the piece in question is twisted up. This is not seen in the image but also twists in the opposite direction to its respective center of gravity.
in short: the error in question is not gravity, quite the opposite is ignoring it. This error is generating enough torque to: overcome the force of gravity, overcome the center of mass, and overcome the lever effect since it is lifting a 4t structure from an off-center pivot.

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10 hours ago, Signo said:

Looks like a kraken of some sort. Maybe a mod bad interaction, maybe part clipping, maybe who knows why. Is it still present when you decouple the rover?

It had not occurred to me to try that, if it is still bugged when I undock the rover. but if I deploy the rover alone without it ever being coupled, it is not bugged.

https://prnt.sc/q2jsh6
https://prnt.sc/q2jso9

And I also managed to try it without mods and the problem continues.

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