Auto-strut "heaviest part"?

[strider3]

My 4 arm Kerbin refueling space station is very prone to the death wobbles unless the innermost part of the 4 arms are auto-strutted to the central hub using "heaviest part". Everything else on the station uses "grandparent part". This is, so far, the only way to keep the thing from flying apart within a very short period (<1 minute). My concern is that I have been told here that as the "heaviest part" may change...especially as I will be adding and removing fuel from this station regularly...when it changes it may cause the death wobble to return. The 4 arms were attached using the Umbra Space Industries Konstruction "weldable" Construction ports, the same ones you see on the arms awaiting tanks, in the screenshots below.

Your thoughts on possible issues using "heaviest part" auto-strutting on these 4 parts? My only other option, as no other auto-strutting type works to keep the death wobble away on this station, is rampant and ugly usage of EAS-4 Strut Connectors going every which way.

 

 

Edited November 28, 2019 by strider3

[Lisias]

Find that heaviest part, made it root, and the auto strut to root.

It's what I do on mine monster crafts.

Sometimes, I wish I could select a "corner part" (as in cornerstone) to use auto struts. Root parts change on docking, and heaviest parts on fuel consumption. Both triggers the Wobble of Doom.

[strider3]

36 minutes ago, Lisias said:

Find that heaviest part, made it root, and the auto strut to root.

Finding that will be almost impossible, I think. There will be many parts with the same weight once construction is complete? Also, this station is already in flight...not sure how you change the root part once you have left the VAB?

Edited November 28, 2019 by strider3

[Lisias]

4 hours ago, strider3 said:

Finding that will be almost impossible, I think. There will be many parts with the same weight once construction is complete? Also, this station is already in flight...

Ugh…. I was in "Developer Mode". Finding the heaviest part on a craft is somewhat simple with the right tools (I just use Notepad++, seatch for all "mass = " and then pick the biggest number on the list). Sorry.

I'm on Mac, so I will show you a TextWrangler screenshot - but other than the looks, Notepad++ works the same.

Changing the autostrut is just editing that "autostrutMode" thingy. Problem: you make a mistake, a simple typo, and you screw up the savegame. Use SAVE if you are willing to try this such a stunt.

 

4 hours ago, strider3 said:

not sure how you change the root part once you have left the VAB?

Every time you dock and undock a craft, you change the root part of the thing. There can be only one (#highlanderFeelings). When you undock, the root of the undocking craft is recalculated/restored (never bothered to check…. something to be done).

However, doing it manually is a pain in the SAS, no doubt. I only managed to do that on small crafts, and I made a lot of mistakes until making it right.  I did the stunt just by the challenge, there're easier ways to accomplish that (see below).

The few stations I made were not that big, and I didn't welded them, I used the big docking ports and then autostrut them to root - at least for my stations, autostruting the key docking ports to root did the trick. But I had choose the root do be equidistant of them...

I think it's easier to spawn a new, fixed station in the place of the current one, and then edit the savefile to move the crew from the old to the new, and then just delete the old station from the savefile.  This will mangle the saveMD5 on the loadmeta file, however - since I don't care too much for career, I just don't care about, but that saveMD5 is there for a reason (for trophies, perhaps?).

Oh, yeah. Use SAVE.  

[paul23]

1 hour ago, Lisias said:

Ugh…. I was in "Developer Mode". Finding the heaviest part on a craft is somewhat simple with the right tools (I just use Notepad++, seatch for all "mass = " and then pick the biggest number on the list). Sorry.

I'm on Mac, so I will show you a TextWrangler screenshot - but other than the looks, Notepad++ works the same.

Changing the autostrut is just editing that "autostrutMode" thingy. Problem: you make a mistake, a simple typo, and you screw up the savegame. Use SAVE if you are willing to try this such a stunt.

 

Every time you dock and undock a craft, you change the root part of the thing. There can be only one (#highlanderFeelings). When you undock, the root of the undocking craft is recalculated/restored (never bothered to check…. something to be done).

However, doing it manually is a pain in the SAS, no doubt. I only managed to do that on small crafts, and I made a lot of mistakes until making it right.  I did the stunt just by the challenge, there're easier ways to accomplish that (see below).

The few stations I made were not that big, and I didn't welded them, I used the big docking ports and then autostrut them to root - at least for my stations, autostruting the key docking ports to root did the trick. But I had choose the root do be equidistant of them...

I think it's easier to spawn a new, fixed station in the place of the current one, and then edit the savefile to move the crew from the old to the new, and then just delete the old station from the savefile.  This will mangle the saveMD5 on the loadmeta file, however - since I don't care too much for career, I just don't care about, but that saveMD5 is there for a reason (for trophies, perhaps?).

Oh, yeah. Use SAVE.  

I wonder how you do these things for larger save files.. My current save file is 200 MB, and just finding the craft takes ages.

[Lisias]

3 hours ago, paul23 said:

I wonder how you do these things for larger save files.. My current save file is 200 MB, and just finding the craft takes ages.

I used to use KOS. KOS allows you to name the part (I think this can be done on recent KSP?). This makes things slightly less harsh. Once I find the craft and the part I want, I keep track of the indentation. "Professinal grade" Text Editors as Notepad++ allows you to open more than one window with the same file, so you can have multiple "visions" of the same file. This also helps a lot.

It's not exactly hard - the problem is that is way to easy to make mistakes.  

[paul23]

Well "easy to make mistakes" is the very definition of "hard" when doing anything technical. I use sublime text and notepad++ a lot, but when crafts themselves are 10k+ lines with up to a dozen level of indentation just following indentation isn't working anymore, since you already have to spent ages searching for the correct line within the module list.

[strider3]

What in this text, tells you this part is the root part? I'm wondering if this hub, being the root part, should have auto-strut turned off?

PART
            {
                name = truss-octo-hub-01
                cid = 4293108844
                uid = 3574767260
                mid = 3209845381
                persistentId = 3698953673
                launchID = 73
                parent = 0
                position = 0,0,0
                rotation = 0,0,0,1
                mirror = 1,1,1
                symMethod = Radial
                istg = -1
                resPri = 0
                dstg = 0
                sqor = -1
                sepI = -1
                sidx = -1
                attm = 0
                sameVesselCollision = False
                srfN = , -1
                attN = right, 109
                attN = left, 145
                attN = back, 73
                attN = front, 43
                attN = top, 1
                attN = bottom, 14
                mass = 0.5
                shielded = False
                temp = 230.81008699473853
                tempExt = 230.48421195134645
                tempExtUnexp = 299.57779829575736
                staticPressureAtm = 0
                expt = 0.5
                state = 0
                PreFailState = 0
                attached = True
                autostrutMode = Root
                rigidAttachment = False
                flag = Squad/Flags/kerbin
                rTrf = truss-octo-hub-01 (Mobil 1)
                modCost = 0
                EVENTS
                {
                }
                ACTIONS
                {
                }
                PARTDATA
                {
                }
                MODULE
                {
                    name = USI_ModuleRecycleablePart
                    isEnabled = True
                    stagingEnabled = True
                    EVENTS
                    {
                    }
                    ACTIONS
                    {
                    }
                    UPGRADESAPPLIED
                    {
                    }

Edited November 29, 2019 by strider3

[strider3]

Went ahead and tried disabling auto-strut on the hub and changing the 4 inner girders to auto-strut "root part"...came apart almost immediately...

[Lisias]

The root part is the very first part on the craft. Crafts on KSP are "Trees" (a programming data structure), it looks lke this when drawn:

The top node (1) is the root. The bottom ones (8, 9, 10, 11, 13 and 14) are "leafs".  This is a binary tree, because each node can have only 0, 1 or 2 "sons". KSP use n-nary trees, i.e., has no limits about the quantity of "sons" a node can have. Being a tree, a "son" can have only one "father", and you can't have circular references - i.e., a node cannot reference a brother, a cousin, or any ancestral. You can't link 14 to 3 neither 4, for example.

EAS Struts is a way to overcome this limitation. 

On a craft file, the ROOT is the part that has no parents, but has "sons". I suggest to edit the craft on VAB/SPH, and then cheat it into the space for testing, instead of trying to hot edit a living vessel. Using the reroot tool is way more convenient.  As I said before, I only successfully rearranged small crafts (about 5 to 7 parts), bigger than that it's just too much hassle to do manually.

At least on the craft files I edited (it's some KSP versions since the last one), its the first PART on the craft file. Each "father" has 0, 1 or more "link =" data, linking to a son - so a root part is a part where nobody has a "link =" to. You can edit the tree by editing that "link =" thingy.

But yet, the reroot tool is the bast way to do that. I explained all of that to you so you can understand what the tool does.

 

On 11/29/2019 at 8:28 PM, strider3 said:

Went ahead and tried disabling auto-strut on the hub and changing the 4 inner girders to auto-strut "root part"...came apart almost immediately...

So the weight of their "sons" is too much for them. You need to auto strut some of its sons to root too, so they can share the load.

Using auto-strut on everything can bite because auto-struts adds more load on the physics engine, and when you overload it the wobble happens, because KSP tries to cut some corners to save framerate and then suddenly the physics engine got flooded by "over-shoots", and eventually one of that overshoots ends up being bigger than the joints can withhold.

 

[Lisias]

On 11/29/2019 at 1:20 AM, paul23 said:

but when crafts themselves are 10k+ lines with up to a dozen level of indentation just following indentation isn't working anymore, since you already have to spent ages searching for the correct line within the module list.

Use a Syntax File for YAML on your Editor. This will allow you to "Fold" and "Unfold" (also known as "Collapse" and "Uncollapse"). making easy to find yourself on the hierarchy.

Use it for .sfs , .cfg and .craft files.

[strider3]

So, for now, I went back and rebuilt the station my "old way"...the Cupola is the root...everything else is grand parented. I know, it ignores much of what you guys are telling me but all my "heaviest" parts are fuel tanks and, therefore, may not remain the heaviest. I suppose I could do some rearranging and make a heavy, fuel carrying part, in the central stack, the root...and never pull fuel from it. I'll save that as plan F (or is it G now ). This has worked in the past with very reduced torque settings on reaction wheels and ensuring the docking craft has SAS and RCS off before docking...and a container full of EAS struts, if needed.

I'll let ya know!

As always...thank you.

[strider3]

SOOoooo...no bueno. By the time I get my engineer out of the cupola, with tool and EAS strut in hand, the thing will fly apart. I haven't even bothered trying to strut it, in truth...I'm not even sure my engineer can carry an EAS strut?. I'm not sure if it's the imbalance when adding the third (of 4 ) arms that brings it on but had no problem with the 1st arm hanging out there waiting for #2? S-I-G-H!

So, I'm going to go with the assumption that the octo-girder modular hub is...inadequate () as the attachment point for the four heavy radial arms (why call it a "hub", then??). I'm going to try redesigning the central stack with a heavy part to attach the arms to...making it the root while in the VAB. I can't think of anything heavier than a girder with fuel tanks in it, tanks that will never be emptied, but I'm open to suggestions.

Here's hoping KSP2 fixes death wobbles...in my mind, once the various parts are permanently attached, nothing should make it wobble itself apart while in a steady orbit with reaction wheels set for very low torque? But, hey...I'm no rocket scientist (obviously! ).

[strider3]

Well...this just gets more aggravating by the minute. The weldable Konstruction port won't attach to any part of the octo-girder. I think I'll go shoot something on my Xbox  instead.

 

[strider3]

So...added 4 BZ-52 Radial Attachment ports to the Octo-girders and then added the weldable Konstruction ports. I think the BZ-52's just add another point for the wobbles, but I'm running out of ideas. I do have a buttload of EAS struts, sooooo...

[RizzoTheRat]

Might be worth taking a look at the Kerbal Joint Reinforcement mod.  Although there seem to be 2 different versions and maybe some kind of spat going on between the mod developers/fans.

 

[Lisias]

4 hours ago, RizzoTheRat said:

Might be worth taking a look at the Kerbal Joint Reinforcement mod.  Although there seem to be 2 different versions and maybe some kind of spat going on between the mod developers/fans.

These ones I know very well .

The Continued is the classic KJR, for the best and for the worst. Some bugs were workarounded, but the thing is usually heavier and impose a heavy tax on modest rigs. On the other hand, the FPS is constant and if you have a nice machine and do streaming, you probably will be better served by Continued.

The Next is a rewrite of the inner guts. Way faster, ideal for potato machines. But the FPS hits the ground when the craft explodes, even on powerful machines (it's when it recalculates every joint). On the bright side, it fixed some bugs by eliminating the causes that could lead to them.

There's no 'off-the-shelf solution' on this, you must try both and then decide what is best for you. Today.