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Re: starship-design: Inter-planetary craft

In a message dated 4/18/00 1:23:12 AM, bfranchuk@jetnet.ab.ca writes:

>KellySt@aol.com wrote:
>> In a message dated 4/17/00 9:49:52 PM, bfranchuk@jetnet.ab.ca writes:
>> Best price?  In theory, it should (with a similar sized market) converge
>> the price of trans pacific air freight.  About $5 a pound.  This is because
>> the general complexity and power levels are similar.
>Can we safely say $150 kg for near term launch costs @ 1 ton payloads?

No.  You need to define the amount of cargo to be launched.  If you want to 
launch a hand full of components like the ISS space station, you probably 
could support a launcher system much below $2000 a Kilo.  You want to build 
and operat a space hotel like in 2001.  You could probably get well below 
$100 a kilo.

>> I worked out some absolute minimam costs assuming beamed powe steam rockets
>> of under a $1 a pound in bulk.  (I think it was about that.)
>> Obviously we won't bother with a starship or anything untill were doing
>a LOT
>> of surface to LEO flights.
>  Beamed energy is still energy hungery. If I remember right it is
>25 watts per ISP unit. Focus and heat is the limiting factors. Where
>does the energy come from? Solar, fusion, fisson power sources?

If its beamed up its from the comercial power grid.  

25 watts per isp is nonsence.  ISP would vary wildly with the type of rocket 
and the reacti mass its using.

>> At a minimum.  When the Air Force was looking in to it, their shuttle
>> replacement could relaunch withing 24 hours with a complete grond crew
>> under 100, and no mission control.
>  Funny a small plane can fly again with just a fill up with fuel.
>Why need space be different?

Same reason fighter planes need hours of servicing between flights.  Higher 
performance, higher stress systems pushed closer to limits.  More complex 
systems.  It'll be a while before we can make something with margins so thick 
you can take such chances.

Oh, but you NEVER just fuel and fly a small plane.  You always spend some 
time doing sheck out on it.  And every so often its taken to a machanich to 
tear down andrebuild and inspect.

>> Or the big resort complexes or liners.  Given the highly educated techs
>> systems usually use, your not likely to get away with rough consructin
>> type facilities.
>I want to build a small complex  with say 75 people in a habitat, not
>the empire state building.(25 rooms).

You couldn't possibly afford it, or support it.  A bigger platform you could. 
 Your small platforms would need to wait until after soimeone built the big 
ones.  Also you need a platform big enough to spin for full gravity.



Good artical!

>Guessing that CH4/O2 costs about the same as O2 / kerosene ( $35/kg )
>we need to pick a realistic figure for costs.

Wait a minutte.  Liquid O2 costs about $0.05 a pound and I think kerosines 
$0.25 a pound?  Where do you get $35 a kilo?