I've never measured it because LOX is cheap. A reasonable first
approximation is to do the calculation using the mass and specific
heat of the tank material vs. the hvap of liquid oxygen. You can't
state an answer generically without knowing what the tank is made of
and how thick it is. Also need to include the heat loss needed to
bring the LOX down from dewar pressure to atmospheric; flowing out of
a dewar that is sitting at 200 psi down to atmospheric requires
boiling off some liquid.
Then you'd also have to measure the boiloff rate when the tank is
full, which varies significantly depending on the thermal environment
of the tank. If it has a common bulkhead with a fuel tank, that's a
significant source of heat that can bleed into the tank.
I recall Charles Pooley doing the calculation at one point on list,
it's probably in the archive. But it's a fairly straightforward
calculation.
Regarding insulation, a quarter inch of cryogel or pyrogel is a better
choice than an inch or two of styrofoam or spray foam. It's magical
stuff.
You should never show up to an operation with just barely enough LOX.
On Sat, Sep 10, 2016 at 7:50 PM, Brian Feeney <alaiadesign@xxxxxxxxx> wrote:
Can anyone provide some comments, experience on the boil off losses when
filling an ambient temperature LOX tank for the first time prior to flight,
and then say refilling within a few hours - say 3 hrs - with little LOX
remaining for a re-flight, maybe no residual LOX in the tank.
Tank conditions - about 10 m3 volume, insulated for flight with 1 to 2
inches of material X (not specified yet), say ambient temperature is a
beautiful day in Mojave Cal. :)
I know LH2 is beyond the scope of the list but if anyone can comment re the
same conditions above on the losses at fill and refill, that would be
appreciated.
Thank you!
Cheers
Brian Feeney
