[AR] static tests (was Re: SpaceX F9 Launch/Update -- Live Link)
- From: Henry Spencer <hspencer@xxxxxxxxxxxxx>
- To: Arocket List <arocket@xxxxxxxxxxxxx>
- Date: Thu, 24 Dec 2015 19:09:36 -0500 (EST)
On Thu, 24 Dec 2015, Henry Vanderbilt wrote:
Probably irrelevant; no one else static tests before launch and the risk
is generally estimated to outweigh the very limited benefit.
I suggest that no one else static tests before launch because everyone
else till quite recently has been implicitly designing their boosters
for a single use only. While it may not be possible to design every
subsystem to *reliably* last for only one use, the chance that they may
have succeeded for one or more subsystems helps explain the traditional
view that there's too much risk.
I think the key question is whether a static test is a sufficiently
traumatic :-) event to need significant inspection and refurbishing
afterward. If the static test went okay but you've still got to work over
the hardware, then it's a separate firing event that puts wear and tear on
the equipment (and the crews) and doesn't tell you very much about what's
going to happen next time. As such, doing them routinely is probably not
a good idea. That was certainly the conclusion reached after early
experience on the US expendables (Thor, Atlas, etc.) -- indeed, there were
several flight losses attributed to component wear from static tests.
But if you *don't* have to touch the hardware afterward, then it's much
more meaningful: it verifies that (most of) the hardware is ready for
flight. Certainly XCOR reported that on the EZRocket and their RRL bird,
brief preflight engine tests found a lot of things that would otherwise
have caused (more expensive and more hazardous) mission aborts.
Henry
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