Re: starship-design: What is safest?

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

Kelly wrote:

>>But is designing for a doubling of lifetime impossible in the next few
>>decades?
>>In what way can current Eartly goods be compared to the equipment we need.
>>Are there any goods of which lifetime doesn't depend on costeffectiveness?
>>(Ie. Are there manufacturers for whom it pays to design a 3 times more
>>expensive product but with a 2 times longer lifetime?)
>
>Impossible?  In some cases yes, in others no.  Certainly many things could be
>designed more resilantly, but the military has pushed that pretty hard already
>in a lot of areas.

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.

>All in all, I'ld expect we could improve a lot of stuff, and have assumed that
>for the 40 year life expectence assuption.  Geting even that far is iffy,
>beyond seems really unlikely.


>>While an engine may be more robust than "micro systems", it also has to cope
>>with orders of magnitude more stresses. Won't these stresses speed up metal
>>fatigue beyond proportion?
>
>To a degree, but the drive is only run a few months, rather then decades, and
>has to be rated for full operation for those months under any condition.  So
>it would need a lot of reserve toughness built in.

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.

Timothy