How to keep two jumbo fuel tanks together?

[Monkeh]

I've tried a few different things to keep a stack of two jumbo fuel tanks together, from complicated beam/strut structures to hardpoints over the join to girders and struts yet more often than not, when starting the gravity turn, they break apart and leave me being pushed by separated boosters. Sometimes they don't break apart though, which is most confusing, as I think I've cracked it, relaunch for a 'serious' flight and find them breaking apart again. Most annoying.

Anyone have any tips for stopping this from happening?

[kahlzun]

One possibility is to use a web of 8 struts that bridge the gap over them, alternatively mount your engines at the front of the ship so it pulls instead of pushes.

Sometimes turning off the gimbal can help.

[dave4002000]

You could always get the UbioZur Welding part pack that specifically includes two jumbo tanks welded together to make it one part.

http://forum.kerbalspaceprogram.com/showthread.php/38577-0-20-UbioZur-Welding-Ltd-Lower-your-part-count

[Johnno]

Keep it simple. 3-4 struts going across the seam on each couple is enough. You don't need to start doing complicated stuff like cubicstruts and cross stitching until you get very heavy payloads.

And the fact that it sometimes happens and sometimes not is because you've created weakspots that are right on the edge of failing but won't do so unless they get that extra bit of stress, which may well depend on one percent more or less thrust and one degree more or less tilt per second.

[Cheebsta]

Like others said, strut the seam itself. I just wanted to add that it takes a little toying with their placement to get them to bridge it sometimes. What I do is move up the bottom tank until it jumps onto the top tank, click, and then go down just enough that the bottom tank lights green to finish it off. A lot of times the strut is so short it looks like just the two ends stuck together.

[Monkeh]

I didn't realise you could strut the seam itself. That seems like a very simple way to fix this problem. Pretty sure I tried it and it didn't work, I shall have to be more patient with the positioning then I suppose. Thank you all.

[Skorpychan]

I use the small cubic octagonal struts to attach regular struts over seams like that. Seems to work well, stops them wobbling.

[wyleEcoyote]

I use the small cubic octagonal struts to attach regular struts over seams like that. Seems to work well, stops them wobbling.

^ I just installed KSP last night and this is what I did. I attached 2 struts in an 'X' across the seems in the front and back ( I saw some one do this in a very nice tutorial). Seemed to be very stable.

[dave4002000]

Be careful when allowing struts to intersect each other. Sometimes the physics engine will do weird things when that happens. I try not to let any of my struts touch each other.

[Skorpychan]

I just use a bunch of the cubic octagonals, and do the struts vertically downwards. Works well enough to get them over decouplers.

[Amoun]

I can say that the X positioning works really well, and like you said, be patient and precise. When it comes to welding stuff together, you gotta experiment with positioning, but as I said, the X always works for me between the tanks and the stages.

[mellojoe]

If you look on YouTube there and search for "Kerbal Space strut stitching" you will see a very simple technique. Just put 4x or 6x symmetry and place struts across the connecition between the two tanks. I use this method for all my stacks on large tanks.

[rosenkranz]

depending on the struts you're using. for stocks struts 4x or 6x maybe necessary. I use the heavy strut from one of the mod packs (novepunch i think) and 3x seems like more than enough for even the heaviest of loads. Often just one at the seam is enough.