Creating a H strut configuration

[sedman]

I'm trying to create a H strut configuration, with 3 x 5m robotruss pro.

I have a bunch of mods, including editor extensions, but it still doesn't seem possible.

I change the roots, I can get the middle strut to surface attach, but I can't get the last to surface attach to the middle.

I know I can build another way, but its not as strong and stops me from mounting landing struts in my desired spot.

This is for a rover, I'd paste an image of what I'm trying to achieve but I don't have an imgur account.

Is there any way to form a H strut configuration with 3 x truss?.
I'd be happy to modify an existing part to add another attachment node to the middle, but I cant work out now to do the node_stack, node_attach sections yet.

TIA.

[Snark]

3 hours ago, sedman said:

I'm trying to create a H strut configuration, with 3 x 5m robotruss pro.

I have a bunch of mods, including editor extensions, but it still doesn't seem possible.

I change the roots, I can get the middle strut to surface attach, but I can't get the last to surface attach to the middle.

I know I can build another way, but its not as strong and stops me from mounting landing struts in my desired spot.

This is for a rover, I'd paste an image of what I'm trying to achieve but I don't have an imgur account.

Is there any way to form a H strut configuration with 3 x truss?.
I'd be happy to modify an existing part to add another attachment node to the middle, but I cant work out now to do the node_stack, node_attach sections yet.

TIA.

Please post a screenshot.  You don't need an account to use imgur.  Just go to imgur.com, choose "upload," drag-drop your image file, couldn't be simpler.

I have no idea what an "H strut configuration" is, so you'll either need to post a screenie or describe it better.

One thing you need to understand about KSP:  you cannot build a closed loop of parts.  Ever.  In KSP, every ship is a "tree" with a root part.  Every part (except the root) has to have exactly one parent, and can have as many child parts as it wants, but the child parts can't connect to each other or to any other part that's already in the rocket.  It simply cannot be done.

There are only two exceptions to this:  fuel ducts and strut connectors (which most KSPers just call "struts").  By "strut connector" here, I mean specifically this, and not any of the other parts with "strut" in their names such as this or this.  The strut connector can connect any two parts on the rocket, and that is how you can strengthen your ship.  Trying to use other parts to build a closed loop just won't work.

[sedman]

http://imgur.com/jLqMnxX

As you say, its simple...

 

This is what I want to achieve, before I go building a whole bunch of stuff on top...

Edited January 10, 2016 by sedman

[Snark]

Not sure why you want to build that shape, but there's no reason why it shouldn't be possible... just be aware that although you can attach four different things to the four ends of the H, you will not be able to attach any of those four things to each other (except with strut connectors).

As to why you can't make that connection in the middle:  I assume it's because that piece you're using hasn't been configured as "surface-attachable."  I say "assume" because that's from some mod, it's not a stock KSP piece, so I don't know exactly how it works.

If indeed the designer of the piece has made it so that it can only connect at the nodes, then you'd need to add some piece to the middle of the existing girder that is surface-attachable, which exposes a connection node to the side.  For example, the BZ-52 is good for this.

[*Aqua*]

You can also attach them straight and then rotate and translate them. Doesn't even take 10 seconds.

[swjr-swis]

22 hours ago, sedman said:

I'm trying to create a H strut configuration, with 3 x 5m robotruss pro.

I have a bunch of mods, including editor extensions, but it still doesn't seem possible.

I change the roots, I can get the middle strut to surface attach, but I can't get the last to surface attach to the middle.

I know I can build another way, but its not as strong and stops me from mounting landing struts in my desired spot.

This is for a rover, I'd paste an image of what I'm trying to achieve but I don't have an imgur account.

Is there any way to form a H strut configuration with 3 x truss?.
I'd be happy to modify an existing part to add another attachment node to the middle, but I cant work out now to do the node_stack, node_attach sections yet.

TIA.

@sedman, tl;dr: play with the order of building, and make a subassembly. I'll explain:

• Place your first strut truss. This will become your 'right' strut truss, instead of the center.
• Surface attach your second truss to the side of the first, visibly close to the center of it but don't worry too much about exact placement.
• Select the Offset gizmo. Click the second truss, and make sure you are i 'absolute' mode (F key). Without actually pulling on any of the arrows, click any of them. The second truss will automatically shift whatever minute amount it needs to be exactly dead center.
• Place a temporary third truss on the free end of the second one. Now select the Root gizmo. Make that last temporary truss the new root (click the 2nd strut then the last truss).
• Now you are able to Mod-click the center strut to select the 'T' you made. Drop that into a new subassembly. You now have a perfect 'T' of two trusses that is attachable by the bottom end.
• Clear everything, and place a new first truss. This is now your 'left' truss of the H.
• Select your T subassembly, and surface attach close to the center side of the one on screen.
• Do the Offset gizmo centering trick again - select the Offset gizmo. Click the center truss, and since you're still in 'absolute' mode (F key), simply click one of the arrows without pulling. Your 'T' is now perfectly centered on the side of the truss.
• If you wish, now select the Root gizmo again and make the center truss the root.

Voilá, perfect H configuration with 3 struts trusses.

Edited January 10, 2016 by swjr-swis
strut != truss

[swjr-swis]

Btw, a tip: you can attach the probe core to the center of the center strut, so the navball is always spot on, by either placing it on a surface attached octagonal strut (easy mode), or if you wish/are ok with clipping, by Mod-F12 allow clipping, then stack attaching to one of the ends of the center strut and offset/rotate it to the desired position (saves you one -tiny- part).

 

[swjr-swis]

I thought I had a clever way of maintaining mirror symmetry, but it doesn't work that way, sorry. first method works, just be aware you won't have mirror symmetry to continue the build.

Ok, a different way of doing this that will maintain mirror symmetry to aid in further building, but it needs an extra strut truss in the center:

• start with the probe core first.
• select the truss for the center. Engage mirror symmetry. Place on the back/bottom of the probe core, but not on the stack node, you need to surface attach a little to the side. If you have mirror symmetry engaged, two trusses will appear, both offset a bit to the side.
• Rotate gizmo one of them 90 degrees until their are in each other's length direction. These two trusses now form your 'center' truss. (so to get a same length to the others, you might want to pick a shorter truss for this, if that mod-pack has it).
• Offset gizmo the center trusses to your liking so they look attached to each other (also, a little to the back so the probe core is outside the trusses... otherwise you won't be able to click it later).
• Place a new truss stack attached to the outside ends on the center trusses.
• Rotate gizmo them 90 degrees
• Offset gizmo them so their sides are centered on the ends of the center trusses. In absolute mode, this should be spot on center

Not a perfect H the way you asked, but the rest of the rover can be build taking full advantage of mirror symmetry.

Edited January 10, 2016 by swjr-swis
alternative method with symmetry, and strut != truss

[sedman]

3 hours ago, swjr-swis said:

@sedman, tl;dr: play with the order of building, and make a subassembly. I'll explain:

• Place your first strut. This will become your 'right' strut, instead of the center.
• Surface attach your second strut to the side of the first, visibly close to the center of it but don't worry too much about exact placement.
• Select the Offset gizmo. Click the second strut, and make sure you are i 'absolute' mode (F key). Without actually pulling on any of the arrows, click any of them. The second strut will automatically shift whatever minute amount it needs to be exactly dead center.
• Place a temporary third strut on the free end of the second one. Now select the Root gizmo. Make that last temporary strut the new root (click the 2nd strut then the last strut).
• Now you are able to Mod-click the center strut to select the 'T' you made. Drop that into a new subassembly. You now have a perfect 'T' of two struts that is attachable by the bottom end.
• Clear everything, and place a new first strut. This is now your 'left' strut of the H.
• Select your T subassembly, and surface attach close to the center side of the one on screen.
• Do the Offset gizmo centering trick again - select the Offset gizmo. Click the center strut, and since you're still in 'absolute' mode (F key), simply click one of the arrows without pulling. Your 'T' is now perfectly centered on the side of the strut.
• If you wish, now select the Root gizmo again and make the center strut the root.

Voilá, perfect H configuration with 3 struts.

Did you actually run through this process?
I've tried exactly as you detailed, plus a few more permutations and I just cant get it to surface mount, I always end up stuck at the point in the image I attached - I have a node on the T subassembly, but it wont surface attach no matter what I try.

I think I'll just give up on it and have the middle of the H as two sections, really just need the strength on the outer beams anyhow, just frustrating.

edit: resorted to editing the part.cfg, I'll have to remember I did that...

 

Really do appreciate your help though.

Edited January 10, 2016 by sedman

[swjr-swis]

5 hours ago, sedman said:

Did you actually run through this process?
I've tried exactly as you detailed, plus a few more permutations and I just cant get it to surface mount, I always end up stuck at the point in the image I attached - I have a node on the T subassembly, but it wont surface attach no matter what I try.

When I wrote that? No. But I didn't need to because I can practically dream it. I do it a lot.

But here's pictorial proof that it works exactly as I said:

 

The only thing I forgot to explicitly state, in the 2nd to last step I described, is that KSP will sometimes not pick the expected place for the attachment node of a subassembly, and it may look wrong. But ignore how it looks and just go ahead and place it anyway. It will work, just needs one more offset gizmo step.

I added a better method as 'demo 2' to the imgur album. This one does keep mirror symmetry, and is actually simpler. Like a lot of things Kerbal, even putting parts together can be 'overengineered'. I'm leaving the first one unedited, because it illustrates a few editor tricks that could be useful some day, and to serve as general amusement at my expense.

 

5 hours ago, sedman said:

I think I'll just give up on it and have the middle of the H as two sections, really just need the strength on the outer beams anyhow, just frustrating.

edit: resorted to editing the part.cfg, I'll have to remember I did that...

 

Well like I said in the post after, what you initially asked for, while perfectly possible, is not the best base for a rover anyway, because it screws up mirror symmetry. So probably best to do as you say and do the center as two sections.

In fact, clever use of the offset and rotate gizmo would make the center strut truss completely unnecessary: you can have the two side trusses 'floating' to the sides of the probe core without any visible connection between them at all, and as far as KSP physics is concerned, they'll act as strongly attached as if they were touching. I can show you that trick too if you are curious (it'd allow mirror symmetry for building the rest, you'd save on the weight of one truss, and the probe core would be both root and perfectly centered for navball operations).

Edited January 10, 2016 by swjr-swis
strut != truss, and better method documented

[sedman]

Awesome, you really know all the tricks. If I wasn't so impatient...

I just pasted in the following into the IR_Segment_TrussLarge_5m00/part.cfg. Gave me the nodes I was after, I have to remember I did it though - update and its gone.

node_stack_right = 0.1823258, 0, 0, 1, 0, 0, 0
node_stack_left = -0.1823258, 0, 0, -1, 0, 0, 0
node_stack_back = 0, 0, 0.1823258, 0, 0, 1, 0
node_stack_front = 0, 0,-0.1823258, 0, 0, -1, 0

If I hadn't spent a few hours designing, testing and then building this on the moon (Extraplanetary Launchpad), I'd go back and do it properly...