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Old October 29th 18, 02:49 AM posted to sci.space.policy
Fred J. McCall[_3_]
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Default US Air Force explores space-based cargo operations, confirms talks with SpaceX

JF Mezei wrote on Sun, 28 Oct 2018
14:02:38 -0400:

On 2018-10-27 17:51, Alain Fournier wrote:

BFS will burn liquid methane. I'm not sure what would happen if you
replaced the methane with LNG. Possibly it would fly, possibly it would
go kaboum. Even if LNG is mostly liquid methane, there typically is near
10% of ethane, propane, butane and small amounts of other stuff. In some
cases the difference can have consequences.


Are rocket engines extremely sensitive to fuel density? or do they allow
for a range of density so that the turbines don't go kablooey if fed
with slightly different fuel?


The density difference between liquid methane and LNG is (at most)
around 10%. It's typically much less. Navy fighter planes use JP-8
ashore and JP-5 at sea. The two fuels vary in density by about 5% and
have different properties. Given that, I wouldn't expect a rocket,
which is a much simpler machine than a jet, to have problems over
minor differences in fuel density.


--
"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."
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