Re: starship-design: What is safest?

[TLG.van.der.Linden@tip.nl (Timothy van der Linden)]

Kelly,

>>What areas and why would they do that? What if a 2 times longer life means a
>>3 times higher price? From an economical view, the latter would likely make
>>little sense, so I wonder if the military did research in that direction.
>
>The Mercedes Benz economics.  Military systems do get that kind of treatment
>since they HAVE to work, and will be used in the worst situations.  NASA and
>space systems get that treatment sometimes too.  But to a degree it is always
>assumed you can fix things in a decade or four, and you usually throw things
>away, even if working fine, after a half century or so.

What military system HAS to work? Virtually all systems have backups of some
kind. While the backup is being used, the primary system can be repaired or
replaced with all the outside help that may be needed.
In case of field equipment where no direct outside help is available there
too are many (although less efficient) backups available. It would not be
very smart to bet on one single system during a fight, no matter how well
designed.

>Some things are easy to make more long lived.  Heavier structures, thicker
>tubing, better filtration on working fluids, etc will obvioiusly compensate
>for a lot of things, if you can afford the weight.  Circutry, and IC chips are
>a bigger problem, especially if you don't want to dramatically decrease their
>abilities.  Etc..

When parallel computing is made to work, then making computers more robust
is supposed to be easy. Furhermore superconducting magnets are great to
avoid mechanical wear. (I'd suggest you'd use these on your hab train.)
Also shielding equipment from a normal moist, temparture fluctuating, dusty
environment increases lifetime significantly.

>>Reserve toughness? So one can build in more than enough reserve (double?)
>>toughness for engines, but not for micro objects that have much less
>>stress...
>>This argument doesn't fully convince me.
>
>The engines stress would be simple structural and thermal loads.  So you can
>compensate with tougher structures.  Because of their scale the kind of
>corosion or microdamage that would criple a micro object, would be phisically
>to small to effect the performance of a macro object.  Think of a pit of
>corrosion the size of a pencil point on the surface of a sheet of metal as
>think as table top.  Now think if the same corrosion on the srface of a IC
>chip, or a junction of an printed circut board.  The very scale of the systems
>make one vulnerable, the other indifferent, to the same damage.

"Simple" structural loads? While the exhaust of a rocket engine looks crude
and simple, the complete engine consists much more than that. I wonder if
the fusion engines make the design simpler. That little bit of corrosion you
talked about may very well affect reflectivity/conductivity that will
escalate the corrosion within seconds (or less).
If an engine part fails, disasterous things will happen. If a circuitboard
fails, it likely can be repaired before lifetreathening situations arise.

Timothy