Building a stock Torus

[Sheppard]

Hello everyone,

I've been searching on the forums for a way to build a stock torus and couldn't really find a good enough guide.

I tried building one with a Mk2 crew cabin and a Mk2 fuel tank, by repeating that pair and rotating it by the same amount each time. And I got this:

Now comes the tricky part: how do you get the last component to attach to the first one? Otherwise the ends are loose and the whole thing falls apart. I have marked with a red circle the attachment nodes that appear free, from the first and last component. I have also tried to attach some girders and struts there but it won't hold.

Any advice on completing the circle? Am I doing something wrong in the building process?

Thanks in advance for the tips!

Edited October 23, 2015 by Sheppard

[steuben]

you can't. the system won't do loops.

you'll have to strut it a bit.

[DancesWithSquirrels]

Struts. Attach some struts - leave symmetry off/set to 1, or it will strut all of your modules together.

[The following may be incomprehensible without some CS background, but I'll give it a try]

The base KSP craft construction is essentially a tree extending off the root part - a root pod links to a parachute in one direction, to a tricoupler in the other, the tricoupler links to fuel tanks, each of which links to a Terrier engine, etc. There are no loops, you can't trace the parts from the pod through various connections and back to the pod.

Struts (and fuel ducts, which are struts with extra) are the exception to this. They can connect any arbitrary part to anything else (assuming you can reach it), and are great for adding rigidity as well as fuel control. In the craft files they are treated as branching from the part you start them on, with a note as to where they go. The physics engine uses them along with the rest of the craft to determine stresses and flexing.

But struts and fuel ducts don't add connections to the tree structure - you can't pick up a part and drag parts from a separate branch, parts that are only connected to it via struts. If you strut together the three fuel tanks in my example above, then drag one around in the VAB, the other tanks will not move.

Edit: In your example you actually have two loops, the upper and lower loops in your second image, not just one. I suspect that either one of your radial arms is detached at one end, or that you unconnected parts at both points perpendicular to the radial arms, both where you showed the disconnect and on the opposite side. Put your torus on some launch struts and see what dangles, strut as needed.

Edited October 22, 2015 by DancesWithSquirrels
Two loops!

[FlyingPete]

You can use docking ports to make the connections. In the VAB, they won't be connected, but as soon as it's loaded on the launchpad, the adjacent ports will connect. You can use this method to double-dock spacecraft sections to each other.

I'd launch the torus in sections and assemble it in orbit, using docking ports to join the quarters together.

[Sheppard]

Ok, I'll give it a try with docking ports, seems more elegant than strutting. Hopefully I can place the docking ports in the right position.

[Snark]

First thing that popped into my head when I saw those pics:

1. Whoa, cool, hats off to you!

2. That thing's gonna be fun to launch...

[Claw]

Yep, struts. Tex_NL wrote a tutorial on this very topic.

http://forum.kerbalspaceprogram.com/threads/62130-Tutorial-Circular-station-building

Cheers,

-Claw

[StormKat]

2. That thing's gonna be fun to launch...

Yes. Yes it will.

[DancesWithSquirrels]

Sheppard - You mentioned not being able to strut your torus at the separation point. Were you trying to strut the segments on the outside of the torus?

Struts won't go around edges, and the outside surfaces aren't parallel; you would need to strut on the inside of the torus, or (with careful mousing) between the endcaps of your two torus sections. But you can't go around corners.

[Sheppard]

Sheppard - You mentioned not being able to strut your torus at the separation point. Were you trying to strut the segments on the outside of the torus?

Struts won't go around edges, and the outside surfaces aren't parallel; you would need to strut on the inside of the torus, or (with careful mousing) between the endcaps of your two torus sections. But you can't go around corners.

I was trying to attach them on the edges and at the center between the 2 parts. It didn't hold, probably because the mass of the whole thing is quite big, even with all the fuel depleted. Will try a new design with docking ports. If I have time, I hope I can return tomorrow with the results.

PS: It didn't hold on the launchpad, but it did with gravity hacked, to simulate orbit conditions. It had to hold even under Kerbin gravity in order for me to launch the damn thing. I imagine 2 halves united by docking ports, launched into orbit by placing them on the sides of a hell of a towering rocket, facing vertically. It will be fun to launch, and probably will take a lot of time with all the low fps. Can't wait for 1.1 to get rid of this aspect in the matter of launching huge ships.

Edited October 22, 2015 by Sheppard

[Tex_NL]

Yep, struts. Tex_NL wrote a tutorial on this very topic.

http://forum.kerbalspaceprogram.com/threads/62130-Tutorial-Circular-station-building

Cheers,

-Claw

Thanks for the link Claw. I was just about to do the same.

(I really should update that tutorial to 1.0.X some day.)

[Claw]

PS: It didn't hold on the launchpad, but it did with gravity hacked, to simulate orbit conditions. It had to hold even under Kerbin gravity in order for me to launch the damn thing.

Ah, well that's a different problem entirely.

For launch, you'll need to build the lift stage downward, then also strut up from the lift stage to the ring. That's about the only way it'll be stiff enough to handle the launch. You will also have to contend with the excess drag and lift created by launching a ring made out of Mk2 parts placed at the top. (As if you added a bunch of control fins and some modular girders.)

If it were really me, I would get creative with engine placement below the ring, then find a way to mount fuel above it. Then strut down from the fuel tanks to the ring in a hub-and-spoke fashion. That setup would use the station ring as a stabilizing structure. You'll likely need enough fuel in the first stage to establish a suborbital, so that you can safely separate the first stage. I would continue on, but I already feel like I'm telling you how to have your fun.

Good luck,

-Claw

[Sheppard]

So with a bit of fiddling around and a small redesign, here is my WORKING, COMPLETE, STICKING, FIRST TORUS. Will try to launch it in one go, as it is, without assembly in orbit (althoug it's only 3 pieces), just for the fun of it. Here are some pics:

Docking ports for a complete circle attached at all nodes:

View from above:

Delivery option:

3...2...1...ABORT...Oh, never mind...Here we go!

It's ALIVE! Muhahaha! Well, until about 2300m. Need more Large SAS units.

Will return with pics once it is in orbit and docked to the rest of the station.

PS: Thanks everyone for the great advice. Now I know how to build a stock torus!

[Vicomt]

I built mine in two halves, but still launched them both at the same time, along with a tug to attach them to the station core, which I'd launched previously.

Here's my launch and assembly slideshow.

Javascript is disabled. View full album

You'll get there, it just takes a TON of tweaking and practice flights.

[Claw]

That's pretty sweet. I can't recall seeing an oval station like that before. Nice job.

Cheers,

~Claw