[ExI] Eyes on the Solar System

[spike at rainier66.com]

...> On Behalf Of Stuart LaForge via extropy-chat
Subject: Re: [ExI] Eyes on the Solar System


Quoting Spike:

> ...
>>... (Why?  Because we don't have enough rocket engine designers anymore, 
> that's why.)  So NASA is left throwing away hardware after each flight
which was designed with a 10 year 50 cycle life.  Damn.

>...It boggles common sense. Why is NASA being so deliberately wasteful?  
The selfish monkey in me understands why old-school NASA techs would want to
eschew Elon's new-fangled engines and shit, but if you were going resurrect
old designs from the mothballs, why resurrect the Shuttle engine when you
could have resurrected the ONLY heavy lift design that has made it beyond
LEO i.e. Saturn V?

Heh.  Thanks for that, Stuart. 

As you pointed out in the subsequent paragraphs, the Saturn V motors were
kerosene burners, or RP-1 if you prefer a more general term (kerosene is a
type of RP-1 (car fuel is octane, kerosene is mostly twelve-cane, RP-1 is a
mixture of canes sometimes known as CnH~2n.)  It has lower performance but
oh it has its big advantages for cost, reliability, handling and safety.


>...Elon would not let a bloated government political statement beat him to
Mars, even if NASA did have its shit together, which its engine designs
leave me in doubt of...

I pondered this deeply on my egg cream walk today and may have a few new
insights for us.

Getting a motor qualified for carrying humans is crazy never-mind expensive,
which is why passenger airplanes stopped changing about 70 years ago.  If
you look at especially the small planes such as the Cessna 172, it is hard
to tell a well-cared-for 1960 model from one made today.  The engine is
nearly identical, because it costs a ton of money to test and qualify any
new design.

The same applies for rocket motors.  Since little has changed in chemical
propulsion tech in the past 60 years, it makes perfect sense to use Saturn V
designs as opposed to Space Shuttle motor designs in my opinion (but they
didn't ask me (the LockMart propulsion guys already know I would say that
(it isn't because of my having any particular love of kerosene (but rather
because when we optimize a rocket, maximum payload isn't the only
consideration (it is an important one (but not the only one.)))))

If a prole wants to design a heavy lift vehicle, she must take into account
development cost, recurring manufacturing costs, one-time manufacturing
costs, reliability, schedule, design risk, all that stuff.  The kerosene
burning Sat V motor was a good reliable product, we know how to build it and
what it takes to set up a factory, all that stuff, but here is the real
heart of the problem: they are having leaky valve problems this time which
will cause them to roll back into the VAB.  My grim prediction is that leaky
valves and lines will ALWAYS plague this design because we damn well know
that liquid hydrogen is inherently hard to handle and dangerous as all hell.
The whole time it is out on the pad after fueling, that hydrogen is boiling
away, boiling cold at about 20 Kelvin in the balmy Florida summer afternoon
which is often well over 300 Kelvin, so temperature delta of nearly 300
degrees.  That vapor hydrogen hasta be gathered up the best you can, because
it is too dangerous to let it vent freely, but that is hard to do.

The oxygen can be left to vent into the air and there is a looooot less of
it, boiling at 90 Kelvin rather than 20 Kelvin.  Heat of vaporization of
oxygen 3.4 kJ/mol vs 0.45 kJ per mole for hydrogen, so Stuart now let those
last two numbers sink in and think about what that means for the amount of
dangerous vapor around that big candle, ja?  The hydrogen vapor, even if we
are struggling to hoover up all of it, means you can't risk venting the
oxygen, but... if you have kerosene fuel, eh, what the hell, there is so
little of it you can just let the oxygen go free.  It is unlikely to cause
problems.

I have probably overstated my case considering you likely know all this
already.




> So... I woulda just bought a coupla Elon's SpaceseXey tail landers and 
> designed a new kerosene burning main stage (with advanced control to 
> dial in a bit of modern automated control system sexiness) which 
> coincidentally, is what LockMart proposed to start with.

>...Well that would made more sense with an engine design meant to withstand
50 launches. I understand they wanting to distinguish themselves from Elon.
But why did they choose so poorly? Did they hire Disney writers for
engineering positions?  Stuart LaForge

I don't know Stuart, but I will make an uncomfortable speculation.

NASA was formed in the height of the cold war.  They set up factories all
over the damn place to reduce risk the commies would try to nuke the rocket
facilities.  The more cynical among us would say they did that to bring more
senators and representatives on board, since nearly every state had a piece
of the space action.  That is also probably part of it, but that strategy
has its costs, if you are ever in charge of a subcontract: you are on the
road all the damn time flying around the country to see your operations.  Oh
that is exhausting and it is expensive.

Musk doesn't do things that way.  He puts his suppliers right there in the
neighborhood, which is why so many little towns near the cape are undergoing
a most dramatic gentrification.  Elon wants his supply lines to be SHORT and
he wants his engineers to be able to DRIVE to their factories and get back
that day.  Oh that would be so nice.  Most of the time when I worked for
LockMart, it was a day-flight over, one day in the office, a day flight
back, oy vey, so wasteful.

Well... NASA still needs senators and congressmen  to support their effort.

Hate to say it, but I think that is a lotta why we are seeing a hydrogen
first stage.  Egregiously cynical is this attitude!  More Eeyore than Tigger
I am!

spike

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