Launchclamps crash into rocket and follow into space

[DMagic]

While tinkering around with the vessel unload ranges I stumbled on a way to force this for any part. It has to do with how and when the vessel is unloaded in flight.

In previous versions there were, I think, two values (landed and not landed) for when vessels were loaded/unloaded and packed/unpacked. In 1.0 there is a new system that better handles vessels in different situations. Check out the VesselRanges class for more details.

What is supposed to happen is that when a vessel is either landed or in space it will be packed first, then unloaded. In flight the vessel will be unloaded before being packed; if a vessel is packed or unloaded in flight below the cutoff level it will just disappear.

What is most important is that the vessel unload range must be higher than the vessel load range: the standard unload range is 2500m and the standard load range is 2250m. If the ranges are the other way around it will try to load the vessel after it is unloaded and all sorts of weirdness ensues. Forcing these wrong values will trigger the continuously repeating, falling part syndrome (with sometimes hilarious results).

As you can see, there is also a lot of debug spam being generated while this happens. I'm not sure if the stock launch clamp bug generates similar log spam as there is a baffling lack of log files available despite multiple threads and an official bug report, am I missing something or are people really this bad at reporting bugs...

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My guess is that something related to this is happening to launch clamps, causing them to not be unloaded properly.

Some of the debug spam being generated is shown below, and the full output_log is here.

[EXC 12:51:24.676] NullReferenceException: Object reference not set to an instance of an object
	Part.ModulesOnStart ()
	Part+.MoveNext ()

Which is repeated while the part is unloaded but within the loading range.

[EXC 12:52:29.777] NullReferenceException
	UnityEngine.Component.get_gameObject ()
	Vessel.recurseCoMs (.Part part)
	Vessel.recurseCoMs (.Part part)
	Vessel.findLocalCenterOfMass ()
	ProtoVessel..ctor (.Vessel VesselRef)
	Vessel.Unload ()
	Vessel.Update ()

Which seems to be continuously repeated after flying out of loading range.

[Claw]

Small update: Based on a save file that someone passed me, I think I've managed to create a fix for this one.

Cheers,

~Claw

[StarStreak2109]

And the fix is what?

[Claw]

Well, it'll be a module on that will be added to my stock bug fixes. Based on my findings of this bug, there isn't really a non-stock way to prevent it, other than avoiding the placement issues as noted above.

Also, due to the lack of .craft or save files, it will have undergone limited testing. So that's why it's taking longer for me to release it.

Cheers,

~Claw

[Gaarst]

I have had this bug of clamps following me into orbit, so far so good, worse thing is that I have to clear the debris from the tracking station, but otherwise nothing really annoying.

And then I made a rocket. That rocket is designed to put ~15t to LEO (built for RSS), and I say "designed" because it hasn't reached over 6000m as a whole once in a dozen launches. Every. Single. Time. Clamps crash into my rocket and destroy it.

It contains parts from SpaceY, but the issue is seemingly due to KSP itself. Otherwise, the rocket is fairly simple: 570t on the launchpad, two SRBs in addition of the core stage (kinda based on Ariane 5). It is centered both in the VAB and on the launchpad and clamps are not off the launchpad.

In the VAB:

On the Launchpad:

I tried positioning the clamps almost everywhere on the rocket, using 2, 4 or 6 clamps, using SpaceY's clamps (so NOT stock clamps !). Clamps are not damaged on liftoff, neither is the launchpad, everything is within the "grid" on the launchpad. The only thing I haven't tried is the radial decoupler thing from Twurtz.

I can provide any file needed (.craft, logs, save...) if anyone asks for them.

EDIT: and adding radial decouplers between the rocket and the clamps doesn't really help, it just causes even more issues with the clamps somehow clipping into the rocket and causing the destruction of kinda capital struts and thus the rocket. Good thing is, if I manage to launch it, rocket doesn't blow up at 6k like before, so I guess that's better ?

Edited August 21, 2015 by Gaarst

[Claw]

If you say it's doing it with stock clamps (and the rocket is all stock), then yes, I will take a copy of your .craft.

Cheers,

~Claw

[Gaarst]

If you say it's doing it with stock clamps (and the rocket is all stock), then yes, I will take a copy of your .craft.

Cheers,

~Claw

No, my rocket is not stock, it contains parts from the SpaceY mod, and I did run it on a modded install (Real Fuels, RSS, SpaceY amongst others). I did report my issue on this thread because the issue is with stock KSP. I thought that the fact that this occurs even on a modded install and with modded clamps (as I said, I also tried with SpaceY's clamps) would help making this thread go further in getting the origin of this bug.

In my post I also mentionned that the "position" solution (putting the rocket at the center of the VAB/launchpad) does not work for me, maybe that can help too.

Anyway, I can always try to replicate the issue with a stock rocket, but then, that wouldn't contribute to solving the issue more than all the previous posts, I'm afraid.

[Squelch]

Just to add some summary to this issue:

The problem is most certainly invoked when any clamp is ungrounded ie not on the launch pad.

Non stock clamps seem to always suffer.

Varying anecdotal reports of stock clamps being fully on the pad, but still follow. (It would be nice if we could get some logs/savegames for these for analysis)

DMagic's theory on the load/packed distances seems to be at the heart of the matter. Prior to 1.0 where the ranges were increased, this phenomenon wasn't seen.

Related to this perhaps, is on approach to clamps that have not been cleaned up, the release sound can be heard as the clamp vessel(debris) is unpacked. This would signify that physics has been reinitiated for the clamps. This has been around for some time, but together with DMagic's theory, it does suggest a race condition.

There are fixes that remove the clamps from the pad after launch, but this possibly removes the recovery funds too. A non mod workaround is to save just after launch and reload. This will remove the problem as the clamp is never reinitialised on loading a save, so therefor do not follow.

Edited August 22, 2015 by Squelch
grammar

[Squelch]

The issue tracker for this can be found here The problem is confirmed, but all further information including logs, saves and craft files are most welcome. Especially for those instances where the clamps are fully on the pad.

Given that there are community fixes and the save/load methods of workaround, perhaps this thread could be marked as such?

Edited August 22, 2015 by Squelch
Fixed, thanks sal

[Claw]

I thought that the fact that this occurs even on a modded install and with modded clamps (as I said, I also tried with SpaceY's clamps) would help making this thread go further in getting the origin of this bug.

In my post I also mentionned that the "position" solution (putting the rocket at the center of the VAB/launchpad) does not work for me, maybe that can help too.

Anyway, I can always try to replicate the issue with a stock rocket, but then, that wouldn't contribute to solving the issue more than all the previous posts, I'm afraid.

Please don't get me wrong, I do appreciate what you posted. I am looking for an unmodded replication of this because I've already gotten to the root problem using FASA clamps via another user's .craft. My issue now is that I need to replicate this in stock to ensure that the same thing is causing the clamps to fly around (and hence the fix works in stock also).

You are also correct. Based on what I see with add-on clamps, if they don't work properly under most "normal" situations, then placement isn't going to matter. Actually, based on what I see from the modded launch clamps, there isn't going to be a workaround other than reworking the clamps themselves or using another add-on to delete them after launch.

Additionally, while the load/pack distances bring the issue to light, it's not actually the root of the problem. "Fixing" the distances back does resolve the clamps following you around, but also results in clamps being deleted (vice being auto-recovered).

Cheers,

~Claw

[Claw]

I've published the fix for this. If you're stricken by this and not opposed to add-ons, you can check it out here: http://forum.kerbalspaceprogram.com/threads/97285-KSP-v1-0-4-Stock-Bug-Fix-Modules-%28Release-v1-0-4b-2-1-Aug-15%29?p=2153984&viewfull=1#post2153984

Please be advised that the clamps are still auto cleaned up by KSP. So please be careful about having extraneous parts hanging off of the clamps themselves.

Also, I've discovered some other weird effects with the clamps...such as flying well outside of physics range and back very close to them (within 300m) and they suddenly collide with the surface (the clamps, and not your vessel). I don't think that's due to my add-on, but still investigating.

Cheers,

~Claw