3
$\begingroup$

Video of stage separation from Rocketlab's latest launch shows clearly what seem to be springs to push off stage 2. Are those actual springs? I've read about linear charges and pneumatic pushers, but never actual coiled springs for stage separation...

$\endgroup$

1 Answer 1

4
$\begingroup$

According to RocketLab Electron User Guide, the interstage is separated via a pneumatic locking system and spring separation. That means, as you said, the springs are what help with separation but it is the pneumatic pushers that lock the second stage in place with the first stage. The pneumatic pushers work by delivering pressurized gas to all separation points expanding all pressure expandable nuts and resulting in the release of all bolts. (As seen in the diagram below). Similarly, the fairing also has this method of separation as it is designed to:

During separation, each half of the fairing is designed to rotate on a hinge away from the payload, resulting in a safe separation motion.

Rocket Lab

Source: Pneumatic Pusher Patent

$\endgroup$
5
  • 2
    $\begingroup$ Oh wow! That's amazing. So they use pneumatic locks instead of pyro bolts, then? But then now I'm wondering: was I wrong when assumed that SpaceX uses pneumatic pushers (meaning, pneumatic cylinders that extend much like Rocketlabs' spring-loaded springs, but without the springs)? And now I'm wondering also if SpaceX might use pneumatic locks instead of the more destructive pyro bolts, since they are all for reusability? Argh, they don't use pyro bolts and I assumed that wrong, didn't I? Someone please say they do use springless pneumatic pushers at least? $\endgroup$
    – user39728
    May 17, 2021 at 16:01
  • 3
    $\begingroup$ I think this may help you with your SpaceX question. On page 17 they discuss the pneumatic system. nasa.gov/sites/default/files/files/… $\endgroup$
    – und3niable
    May 17, 2021 at 16:51
  • 1
    $\begingroup$ So it seems no pyro bolts, then... OK, I'll guess pneumatics like Rocketlabs' system then. But this leaves me wondering still if their pneumatic pushers might be spring-loaded? Any info on that? $\endgroup$
    – user39728
    May 17, 2021 at 18:42
  • 1
    $\begingroup$ Interesting that the patent says pneumatic expandable nuts would sever the connection between the stages but that (linear) pyrotechnic charges would still be in place to apply the positive separation force needed to push stage 1 away. Clearly they've done away with the pyrotechnic charges in their latest launch because that positive separation force is now handled by the spring-loaded pushers. But anyway, yeah, it makes so much sense that SpaceX would have pneumatic expandable nuts too, since those are fully reusable. $\endgroup$
    – user39728
    May 17, 2021 at 18:52
  • 1
    $\begingroup$ Well that patent isn't rocket lab's but it is an example of a pneumatic system that I found. In rocket lab's patents there is no mention of such a system so I found an example that it may be following. cbinsights.com/company/rocket-lab-patents $\endgroup$
    – und3niable
    May 17, 2021 at 19:07

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.