Decouplers can't take compression

[Pixel of Life]

I've been having a lot of problems building really heavy rockets with serial staging because decouplers can't cope with the weight on top of them. This mainly happens with large 3.5 and 5 metre tanks (NovaPunch / KW Rocketry) - whenever I try building anything with those, the thing just collapses on itself even if there are 8 Quantum Struts between the stages holding it together. When the physics are loaded, despite the struts the whole rocket sort of compresses a bit at the decouplers and then bounces back up to its original length and rips itself apart. How do I prevent this from happening?

Edited August 27, 2013 by CaptainKorhonen

[blizzy78]

I'd say you need more struts. Yesterday I was building myself a lifter to transfer a payload of 80 t into orbit, but at least one of the 4 asparagus-style boosters kept falling off before the vehicle cleared the launch clamps. Believe it or not, simply adding more struts to tape the boosters to the main stack helped. I also added struts in an X fashion between every two boosters, just for good measure. The whole thing now flies like it should.

Bottom line: Stock struts are not the most powerful. Also, I've seen Quantum struts fail.

[DChurchill]

Try something like this:

You don't have to copy the ship, just look at how the i-beams and struts are used. It helps a ton with what you're talking about. Think bridge or one of those tall cranes they use on buildings.

[Pixel of Life]

Thanks guys. I found the problem - apparently Quantum Struts' compression strength isn't that high and that's what caused it to collapse on itself. I tried the NovaPunch "Even Heavier Strut Connectors" and it solved the problem - even the largest of rockets are now rock solid, apart from some SAS-induced wobble. But that can easily be dealt with by hand flying until stage 1 separation.

[blizzy78]

Do note that those struts are much heavier.