ferram4

[1.3] Kerbal Joint Reinforcement v3.3.3 7/24/17

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One thing i encountered is: some joint seems to become lower after i installed this plugin.

To be more specific, I'm using NP's escape tower for 3-man pod on a medium docking port, with a parachute pack which has built-in RCS ports (this part also belongs to NP but i don't remember the name of it) installed under the docking port.

When the escape tower is to be decoupled as i'm reaching orbit, the docking port is pushed by the ejection force and break the connection with the parachute pack below it.

I had similar designs before and had never encountered such situation... I wonder if this plugin actually reduce the joint strength between the parachute pack and the docking port.

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@NathanKell: Well, there are three main reasons:

  1. For the most part it doesn't seem to be necessary; there are only a few odd exceptions that seem to be mostly due to the behavior of mod parts, and I don't expect mods to mesh perfectly together.
  2. I'm not exactly sure what breakForce is measured against. I think that it is the force applied by the joint outside of the "Drive" parameters I use to really keep the stiffness in line, but I'm not too sure about that.
  3. What happens when something I didn't anticipate comes along and it is either too strong or breaks when you sneeze on it?

Besides, further thinking makes me think that the actual issue with the parachute was the "crashTolerance" value being exceeded, since that seems to control whether something blows up or not (or is it the "strength" value... I'm honestly not sure. I'll have to look into that). Another possibility is that the workaround I did for the decoupler-no-ejection-force bug is causing the issue; that's been removed and replaced with a solution by a.g. that allows me to get away with not having to do that, so I can test in my build and see if anything happens.

Edited by ferram4

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Sorry, I mean break_ing_ force and torque, for the parts themselves, not the joints. Then when you multiply them by your constant to get breakForce and breakTorque, you'll get sane values. But if it's not necessary, no worries.

(I found that if I use a tractor LES with a high thrust, a high breakINGForce is necessary for both it and what's under it, or it'll rip off. Zander's post reminded me of that experience, and Starwaster mentioning at some point that many (stock!) parts lack any breakingForce and so might have wonky values.)

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One thing i encountered is: some joint seems to become lower after i installed this plugin.

To be more specific, I'm using NP's escape tower for 3-man pod on a medium docking port, with a parachute pack which has built-in RCS ports (this part also belongs to NP but i don't remember the name of it) installed under the docking port.

When the escape tower is to be decoupled as i'm reaching orbit, the docking port is pushed by the ejection force and break the connection with the parachute pack below it.

I had similar designs before and had never encountered such situation... I wonder if this plugin actually reduce the joint strength between the parachute pack and the docking port.

Hmm, i have similar experience with ya. i also use that escape tower on my Katurn, and it pull the docking port out from my pod when decouple.

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Ferram4 Have you considered disabling gravity one you go to pad, and then gradually reintroducing it to help the simulation settle? You can do it by manipulating CelestialBody::GeeASL value. Set it to 0.01 initially, and then bring it back to what it was over few seconds. The point being that at first it settles from the kick to the side (caused by planet rotation), and only then settling against gravity.

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Won't that send various other craft in KSC flying due to pre-existing internal stress and compressed wheel suspensions, like it often does when you hack gravity? Now, if it was possible to disable gravity just for one craft...

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Just found out the Kerbal Engineer parts rubberband like crazy with this mod. It's not a huge issue though. I'll just add the engineer modules to the capsules and probe cores.

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Just found out the Kerbal Engineer parts rubberband like crazy with this mod. It's not a huge issue though. I'll just add the engineer modules to the capsules and probe cores.

Seems like they make your rockets act crazy when they hit water as well.

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Cutting the decoupler force on the Novapunch LES Tower in half from an insane 2000 down to 1000 seems to have fixed the exploding/detaching docking port issue for me.

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Parts from kerbal engineer and a number of other mods have insanely low mass: 0.000001 for engineer. Personally, if you are going to make a part with such low mass and zero drag, I don't see why not make it non-physical altogether and be done with it.

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ferram, have you considered, instead of multiplying breaking force and torque, and otherwise using existing values even as a base, just replacing them with sane values and then using those in your calculations? So many are so screwed up...

Apologies if there's a really simple reason not to that I'm missing, or you already considered and rejected it for good reason...

That's why I raised a point about the breakingForce / breakingTorque values earlier. I'm actually a little surprised that there's a default value as high as 22 because when those properties aren't set in the config file, strange things happen. They always have.

Stock parts fail in situations they shouldn't. Sumghai's Fustek extension parts used to have an issue where the properties were misspelled which had the same effect as the torque/force properties not being set at all and stations with those parts would randomly fail because of it.

Edit: btw, Ferram did say earlier that the only place he's actually multiplying those values is in the launch clamps...

Edit: Wait... Ferram, re: the launch clamps, how about editing the clamp joint's rigidity? You mentioned earlier that if you made joints too rigid they would fail? Maybe if the clamps are made springier that they would be less prone to fail when physics goes haywire?

Edited by Starwaster

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Well... what does your rocket look like? That should give us something to start with. Problems I can think of:

If MechJeb is in control during launch, that could be the problem; it doesn't know how FAR's controls work, so what ends up happening is it tends to over-control and over-correct the rocket.

There's also the possibility that you're just asking for an absurd amount of force to be applied to the rocket to correct its trajectory; if you're flying at full thrust low in the atmosphere when you do this then FAR's aerodynamics will probably apply forces that would tear the rocket apart in a real scenario.

Another possibility is that you're connecting a very heavy part (say a fuel tank) to a very light part (say, a decoupler) that happens to be right near the center of mass of the rocket; such joints are naturally more flexible due to the way physics works in-game and if you manage to get control inputs strong enough to flex the rocket that will ensure that the maximum amount of flexing occurs due to the large amounts of mass on either side of the joint.

I've found that MechJeb's ascent autopilot is fairly useless for FAR launches (surprise surprise), so I've been flying with SAS to stabilize the roll axis while I adjust pitch and yaw. Your comment has lead me to redesign my latest launcher with more care into how the axes are controlled. I am using one large 1900kN KW engine for the core and locking its gimbal, then placing four 'vernier' 100kN coxswain engines around it to control pitch and yaw in the lower atmosphere. I'm also using four delta wings as fins for aerodynamic stability and then putting small control surfaces at the tips for roll control only. Even a slightly sloppy gravity turn was enough to get my 14T payload into orbit. The difference was night and day, thanks for the help!

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@asmi: I've been trying out a similar system that would work for any vessel that loads, whether it's on the pad or it is landed and comes into physics range. So far nothing good has come of it, but I'm hopeful. If necessary I'll implement a similar system that scales up the Launch Clamp stiffness before adding gravity. I'll also have to figure out how to lock user control prior to all of this being completed.

@a.g.: I think I'm just gonna add a check to ignore parts below a certain mass. Make it high enough that probe parts shouldn't be affected, but silly things like that will be.

@Starwaster: If the clamps are too rigid, the forces applied to the rocket cause parts to break off / explode. If the clamps are too springy, the rocket falls to the pad or the extra fall distance results in the rocket bouncing around more, which can break things off.

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Getting consistent CTDs.

- load VAB

- place few modules (i used single stayputnik for testing)

- exit and enter tracking station

- loaded landed craft on Mun

- exit and loading VAB after triggers CTD.

Current mods beside this one (I am currently trying to eliminate rest)

-Kethane

-MagicSmoke

-MechJeb

-EPLP

-B9

-KAS

-Firesplitter

-HooliganLabs

-Spherical tanks

-Alarm Clock

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Perhaps it's a memory issue.

Install the lower texture packs and see if that helps; if it does, then you know that's the issue. If it doesn't, then you'll have to post an output_log.txt so that we can look at it and see if that helps find a problem.

Honestly, this mod doesn't do anything in the VAB, so if it crashes when you switch to that it's probably not KJR.

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Ferram4 Have you considered disabling gravity one you go to pad, and then gradually reintroducing it to help the simulation settle? You can do it by manipulating CelestialBody::GeeASL value. Set it to 0.01 initially, and then bring it back to what it was over few seconds. The point being that at first it settles from the kick to the side (caused by planet rotation), and only then settling against gravity.

That's a very interesting idea, assuming of course that it wouldn't screw up orbits of every craft orbiting Kerbin.

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Sorry that was silly of me not to look into crashlog (didn't expect it to generate) yes i was getting dynamicheapallocator OOM, I guess 8Gb Ram wasn't enough for it. I guess this plugin finally tipped it over the limit. When I tried to remove mods the crash was too consistent with presence of KJP so I assumed it was caused by bad synergy within mods.

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That's a very interesting idea, assuming of course that it wouldn't screw up orbits of every craft orbiting Kerbin.

Wouldn't matter, when your on the pad any craft in orbit is on rails and ignoring changes to physics.

@Garm...not sure how 8gb of ram comes into play...seeing as how KSP is 32bit software.

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Ferram: I don't know if this has been covered, but launchclamps keep holding me back on the launch pad (after staging them off) and even with none connected I still sit there on the launchpad... I tried replacing the launchclamps, but it won't work... Help?

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This mod seems to be problematic with deadly reentry, the DRE decouplers don't separate properly, and my solar panels didn't even shear off during the shock heating of reentry. Otherwise, I love this for launching my massive launch stages into orbit.

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Ferram, just wanted to break up the long line of problems that get posted in your mod threads and say that this mod is awesome, and you're awesome for offering so much support with it. That goes for all your other mods too. Thanks!

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Alright, version 1.3 is out, which fixes the horrible launch clamp bug and implements a bunch of changes by a.g. that make updates occur properly on docking and better approximations of joint forces. There's also a cutoff for masses below which joint stiffening isn't implemented; this can be changed in the config file. Hopefully there aren't any other problems.

@iornfence: So you're saying that you brought a vessel with solar panels deployed from space down to the surface of a planet without the panels breaking. That sounds like a problem with something else, since solar panels breaking off is supposed to be handled by the stock solar panel PartModule; unless you can provide an output_log.txt that can trace the error back to KJR, I'm going to guess it's another mod causing that.

There was a decoupler issue in v1.1; are you sure that you're using the most recent version of the mod? If you're using v1.3, would you be kind enough to provide an example craft so that I can debug it?

@Traches: Meh, I'm used to it. Nobody calls support to tell them they're perfectly fine.

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SWEET! Good just keeps gettin better!

I have to thank you again for this mod and the fast fixes. As a player who enjoys massive builds this is an invaluable tool. This mod has cut my build times by 1/2 at least, not to mention a nice little part count reduction on everything. Also much more simple to trouble shoot and fix huge craft that are not flying properly.

Awesome work, don't think I could go back to playing without this...not to many mods I can say that about.

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