JF Mezei wrote on Mon, 16 Jul 2018
15:36:58 -0400:

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 ?


Basically.


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?


The problem is that as the LOX warms it expands before it boils. So
it's not just boil off. The tank carries a reduced amount of liquid
on the way to boil off.


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 ?


Some small number of hours. SpaceX has aborted launches because minor
delays led to concern about having enough LOX left for the mission.


With regards to Northorp Grunman: The transaction had just been
completed. That Cygnus craft had been launched as Obrital ATK, but was
released from ISS as a Northorp Grunman craft.


Cite? It's irrelevant, but I'm curious how you arrive at that
conclusion.


There is a long period
between the time a merger is announced and the time when the paperwork
is signed and transfer/]urchases of shares executed.


Not so much, no.


--
"Some people get lost in thought because it's such unfamiliar
territory."
--G. Behn