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Old March 19th 17, 03:20 AM posted to sci.space.policy
Fred J. McCall[_3_]
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Default Musk plans for mars

JF Mezei wrote:

On 2017-03-18 12:19, Jeff Findley wrote:

Yes. For ICBMs they're a huge advantage (store for many decades, yet
can be launched at a moment's notice). But large solids have several
disadvantages for launch vehicles.


I was wondering about that.

SpaceX, which developped its own tech instead of relying on external
contractors, did not choose solids.


Because SpaceX wanted actual reusability.


Russia appears to be set on kerosene. right ?


Russia tends to use 'half stages', where they just dump a bunch of
engines off.


However, Arianne uses SRBs.


Sometimes.


With 1970s technologies (era when Shuttle designed), could they have
build the Shuttle with _expandable_ liquid boosters and launch in same
time and budget ?


Yep. One of the designs had liquid fueled flyback boosters.


We've seen that even with 21st century tech, returning liquid rockets to
ground is a challenge, so perhaps having re-usable liquid boosters for
Shuttle was not even close to realistic in the 1970s.


It was just more expensive than the alternative solids.


Were SRBs chosen because it was the only way to make a claim of
re-usability since they can be dunked in salt water and re-used ?


No.


Different slant to question: if re-usability had not been such an
important aspect, would NASA have chosen liquids instead of solids for
the Shuttle boosters or would SRBs still have been a necessary evil to
give the needed performance ?


No. Once they got rid of flyback boosters, solids were bigger 'bang
for the buck' than anything else.


Anyone know if Arianne 5 chose SRBs for engineering or political reasons?


People choose SRBs because they're cheaper for the amount of thrust
they can deliver.


--
"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