Re: [Starlink] some post Starship launch thoughts

[Bruce Perens <bruce@perens.com>]

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Note that if SpaceX wants a sacrificial coating, they have PICA-X and the
sintered silicon tiles.

On Wed, Apr 26, 2023 at 3:31 PM Rodney W. Grimes via Starlink <
starlink@lists.bufferbloat.net> wrote:

> > On Wed, Apr 26, 2023 at 1:41?PM Rodney W. Grimes
> > <starlink@gndrsh.dnsmgr.net> wrote:
> > >
> > > > As always I enjoy the flood of information we get on this list!
> > > >
> > > > still, so far, my research on a nitrogen deluge system (instead of
> > > > water) has come up empty for me, except as a fire suppressant. So
> it?s
> > > > either crazy or brilliant. Or both! I really liked the idea of
> > > > something cooler that was a natural byproduct of the LOX process...
> > >
> > > I dont think cooler does much, isnt it the "energy of vaporization"
> > > that is actually doing all the "work" in this type of system?
> > >
> > > H2O is 40.7 kJ/mol and LN2 is 5.6 kJ/mol so you would
> > > need ~7 times as much LN2 to do the same work.
> >
> > Now that! was the kind of numbers I was looking for!
>
> :-)
>
> >
> > Still, water has to come from somewhere, and be stored. I will keep
> > thinking about it. I like that they seem to think that a water cooled
> > steel plate will suffice.
>
> Water is a pretty ubundant resource...
>
> Now that water cooled steel plate, if you treat it like a sacrificial
> anode in a water heater, ie you expect it to be erroded over time it
> could get interesting.  Energy of vaporization of steel well... lets
> call it iron (Fe) is 340kJ/mol.  Large thick plates are rather easy
> to manufacture, and I am sure they could design the ficturing such
> that the blast held them in place against a concrete foundation.
>
> Also there is probably lots of good research on keeping water
> in contact with steel at high temperatures and volumes, think
> Boiling Water Reactor!  Containing the flying molten slag would
> be a concern I suspect though.
>
> >
> > > And the reason N2 is used as a fire suppressant is again not
> > > because of temperature, but because it displaces the O2 and
> > > suffocates the fire.  N2 is also easier on our ozone layer
> > > than the prior used Halon.  Finally, this is usually
> > > compressed N2 gas, not LN2.
> > >
> > > --
> > > Rod Grimes
> rgrimes@freebsd.org
> >
> >
> > --
> > AMA March 31:
> https://www.broadband.io/c/broadband-grant-events/dave-taht
> > Dave T?ht CEO, TekLibre, LLC
> >
> >
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-- 
Bruce Perens K6BP

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