In rockets like Starship, if 35 Raptors are firing at same time, then in a full-duration static fire test there would be enormous loads being exerted from 35 raptors, on the clamps holding the rocket. What type of clamps/holding technology is being used to prevent the rocket from flying up (or away)?

I understand the load on the clamps will be thrust minus rocket's mass, but in a full duration test the rocket's mass will keep on decreasing while thrust will not decrease in same proportion.

So, how does "holding-the-rocket" technology works?


1 Answer 1


The same way that they hold down Starship from T-1.3 seconds when the engine ignites to T-0. With the stongback clamps and the TE (Transporter Erecter). This information comes from Spacex's numerous Falcon 9 webcasts, so this is information is only correct if Falcon 9 and Starship use the same method.

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    $\begingroup$ Oh boy. I want to know about the mechanism involved in smooth, simultaneous release millions of pounds of thrust. $\endgroup$
    – Eric G
    Commented Mar 20, 2021 at 2:38
  • $\begingroup$ Holding a rocket before T-0 is bit different thing than holding it after T-0. The force requirements would be several folds higher. And also with passage of time, the required holding force will increase further as the total mass of rocket decreases. $\endgroup$
    – Raj Arjit
    Commented Mar 20, 2021 at 10:16
  • $\begingroup$ @RajArjit You are wrong, thrust just before T-0 is equal to thrust just after T-0. $\endgroup$
    – Uwe
    Commented Mar 20, 2021 at 22:46
  • $\begingroup$ @Uwe: I never said of "thrust". I said "holding force". Holding force = thrust minus weight of the rocket. The weight of rocket decreases with passage of time with ejection of propellant. $\endgroup$
    – Raj Arjit
    Commented Mar 22, 2021 at 5:21

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