LV-N motors fall off?

[zeppelinmage]

Part of my station build requires 2 packs of orange fuel tanks. I have the lifter built, and ready to go. Expecting the need, I've strutted the hell out of it. Here she is on the launch pad.

Thing is, once physics kicks in, the entire center stack settles, despite the insane amont of struts I have connected to it. That settling is enough to break off the LV-N nuke engines:

And the inevitable occurs:

Any tips on what to do (other than MOAR STRUTS)? Should I re-think my design? (The central "orbital" stage is going to be beefy anyway, having to move 5 full orange tanks around.)

Edited January 7, 2014 by zeppelinmage

[TheDarkStar]

I think you have a clipping issue. Put a small girder between the tanks the LV-Ns are on and the central stack and see if that helps.

[Richy teh space man]

Do you have the struts from below connected to the LV-Ns? If so connect them to the fuel tanks above instead.

Edited January 6, 2014 by Richy teh space man

[Streetwind]

Do the tanks have to be full at all costs? You can make the upper stage a lot lighter if you remove some fuel from the tanks. Over 90% of their weight is fuel.

If you plan to mount these tanks to a station instead of using them to fuel something, then it might be worth launching them empty (or at least reduced) and then fill them up with a separate refueling run or two.

[Kasuha]

Badly installed struts can make your design even more fragile.

I suggest to remove any struts you may have towards these engines and just install 3-4 struts directly between the tank (or whatever is this LV-N attached to) and the engine.

I used to have issues with landing - chutes opened, engines fell off. Just three such struts per engine solved the problem.

[Z-Man]

Do you have the struts from below connected to the LV-Ns? If so connect the to the fuel tanks above instead.

That. Connections from LV-Ns to the tank above are exceptionally weak; they do not need to be strong in operation, after all.

[Vanamonde]

How about some launch clamps to the tanks the LV-Ns are attached to? If the tanks move less, they might impart less momentum to those heavy engines.

[Kasuha]

How about some launch clamps to the tanks the LV-Ns are attached to? If the tanks move less, they might impart less momentum to those heavy engines.

You might be right. Except there doesn't seem to be much space for launch clamps in the middle. But giving the central column some support from bottom might help.

Edited January 6, 2014 by Kasuha

[zeppelinmage]

Thanks for all the advice. =) I ended up re-engineering the lifter some. I found out I really didn't need all that orbital fuel - cutting back on it actually increased my Delta-V.

I think you have a clipping issue. Put a small girder between the tanks the LV-Ns are on and the central stack and see if that helps.

Good suggestion. I added cubic octagonal struts and that does seem to help.

Do you have the struts from below connected to the LV-Ns? If so connect them to the fuel tanks above instead.

Yeah, some of the struts from below were hooking into the LV-Ns. I moved them so now they're only connected to tanks.

Do the tanks have to be full at all costs? You can make the upper stage a lot lighter if you remove some fuel from the tanks. Over 90% of their weight is fuel.

If you plan to mount these tanks to a station instead of using them to fuel something, then it might be worth launching them empty (or at least reduced) and then fill them up with a separate refueling run or two.

No, they don't need to be full; I just thought it would be more efficient. =) I've now cut back on the fuel weight.

Badly installed struts can make your design even more fragile.

I suggest to remove any struts you may have towards these engines and just install 3-4 struts directly between the tank (or whatever is this LV-N attached to) and the engine.

I used to have issues with landing - chutes opened, engines fell off. Just three such struts per engine solved the problem.

I'll add some struts between them.

How about some launch clamps to the tanks the LV-Ns are attached to? If the tanks move less, they might impart less momentum to those heavy engines.

As Kashua mentioned, there isn't any space for clamps to hook in there. I usually do connect another set of clamps higer up, but it just doesn't work with my asparagus rockets. Also, adding one underneath isn't an option, since there's motors there.

...now to see if she'll fly.

[zeppelinmage]

Thanks, all. The separating LV-N issue has been rectified. Though I still couldn't get the rocket to work right. Mostly it was asparagus issues though.

Right now I've re-thought the whole deal and am just launching completely empty tanks on fewer drive motors. Keeping it (relatively) simple.

Marking this "Answered" since my initial concern has been met.