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Old October 27th 17, 02:33 AM posted to sci.space.policy
Fred J. McCall[_3_]
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Default Were liquid boosters on Shuttle ever realistic?

JF Mezei wrote:

On 2017-10-26 16:27, Fred J. McCall wrote:

And they have to be "certified" for a magnitude (or multiple
magnitudes in the case of something like BFR) more fill and drain
cycles if they're supposed to be reusable.


When dealing with composites, while you certify based on your tests,
must it not be engineered to be refillable an infinite number of times?


Nothing is "refillable an infinite number of times". Your question
isn't comprehensible, so it can't be answered.


Yes, you engineer to a maximum pressure (validate with destructive
test). But when you certify a tank for X refills, isn't it more akin to
stating that after X refills, you saw no defects develop? (as opposed to
stating that defects appear after each fill, but tank will hold until it
has Y defects).


It's a combination of both of those and you don't just build something
random and then determine things by test. You design to performance
targets.


Carbon fibre structures quickly lose their strength/integrity as soon as
there is a defect.


That depends on the defect. Nothing goes from pristine to
instantaneous failure.


A carbon fibre bike won't last long if a crack
develops. Likely won't get you home because with each bump on road, the
crack will get much worse.


Fortunately I don't think any carbon bikes are used in SpaceX
boosters.


--
"The reasonable man adapts himself to the world; the unreasonable
man persists in trying to adapt the world to himself. Therefore,
all progress depends on the unreasonable man."
--George Bernard Shaw