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Old July 17th 18, 04:43 AM posted to sci.space.policy
Scott M. Kozel[_2_]
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Default Soyuz fueling

On Sunday, July 15, 2018 at 2:34:13 PM UTC-4, Jeff Findley wrote:

If you're going to launch (presumably hours) after fueling, keeping the
LOX below the boiling point would be very difficult. Launch vehicles
that do this typically let the LOX boil off and just continuously
replenish with liquid oxygen to make up for the boil off. Most US
launch vehicles have done it this way.

SpaceX Falcon is the exception. They sub-cool the LOX to well below its
boiling temperature to increase its density. Hence the "load and go"
timing of LOX filling.


"We sub-cool the oxygen and methane to densify it, so compared to...
propellants normally used close to their boiling point in most rockets,
in our case we actually load the propellants close to their freezing
point, and that can result in a density improvement of up to around
10 to 12 percent, which makes an enormous difference in the actual
results of the rocket."

"It also makes the... it gets rid of any cavitation risk for the
turbo pumps, and it makes it easier to feed a high pressure turbo
pump if you have very cold propellant."

https://space.stackexchange.com/ques...turbo-pumps-an