Jeff Findley wrote on Tue, 17 Jul 2018
07:24:21 -0400:

In article ,
says...

On 2018-07-15 14:34, 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.

So basically, most launchers get their LOX at just under liquid
temperature and doesn't really warm up over time because the boiling off
process keeps the remaining fuel liquid ?


Yes.


Basic physics. Things at melting and boiling points tend to be the
same temperature throughout. That's why when you boil water on the
stove it pretty quickly comes to a full rolling boil once it starts to
boil at all.

In the case of SpaceX, once they have loaded supercooled LOX, does it
stay put as liquid until it warms up enough for boiling to begin? Or
does boiling happen because of the realitty of Fliorida and the sides of
the tank warming up the supercooled LOX to boiling tempoerature almopst
instantenously, but hopefully keeping the core well below that for long
enough?

As you can see in videos, there is some boil-off. I'm guessing due to
"hotter" areas in the stages like plumbing and etc.


Isn't most of that water vapor rather than 'boil off' LOX?

And if there were a delay, how long would it take before the whole tank
warms up to normal "LOX" temperature just under boiling off point?
Minutes? Tens of Minutes? an hour ? hours ?

Google how long their launch windows are. That's your answer.


As the LOX warms up you're going to spill around 10% of it before it
starts to boil because of the decrease in 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."
--George Bernard Shaw