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I noticed that rocket Lab has a hollow rectangular section strongback made of steel, while few strongbacks like that of Astra [similar size] has a trussed structure for a strongback. is there any advantage of using hollow section, because most of the strongbacks are actually truss structures?

Astra 3.2 Electron - rocket lab

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  • $\begingroup$ Hollow section would provide better protection to the plumbing inside, but add mass. (and might be more affected by rocket blast pressure). I'd also have some concerns about sound energy being reflected back to the rocket body. No clue as to the magnitude of the tradeoffs though, i'll leave an actual answer to the experts. $\endgroup$
    – PcMan
    Aug 28 at 7:03
  • $\begingroup$ I wonder whether Astra's capability of launching from anywhere in the world, and setting up a launch complex within a week starting from nothing but a slab of concrete somehow fits into this. $\endgroup$ Aug 28 at 8:00
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    $\begingroup$ Without structural diagrams, how do you know the Electron strongback uses a hollow shell? Your Astra image even gives an example of an external cladding covering an underlying truss. Here you can even see panels on the Electron strongback that might line up with the cell structure of an interior truss: s.yimg.com/os/creatr-uploaded-images/2020-08/… $\endgroup$ Aug 28 at 12:27
  • $\begingroup$ That's a fair point, but, this photo shared by Rocket Lab shows that it is a hollow structure. sorry, I shud've included this in the question. twitter.com/RocketLab/status/… $\endgroup$
    – suzi Venus
    Aug 28 at 12:48
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    $\begingroup$ @suziVenus you sure there's not a truss hidden in there? Okay, yes, that's a rather better picture. Looks heavy, but cheap and fast to engineer and fabricate (the two halves even look nearly if not completely identical). Note that Rocket Lab's strongback doesn't have to pack away into a shipping container with the rocket for transport, it rides a short, straight set of rails between the assembly building and the launch pad. I don't have insight into their design process, but suspect it can be summed up as "it's all they needed". $\endgroup$ Aug 29 at 0:54

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