And lo on Thu, 17 Jan 2008 04:35:39 -0000, Chambers  

<ben### [at] pacificwebguycom> did spake, saying:

> Phil Cook wrote:
>> And lo on Wed, 16 Jan 2008 02:49:42 -0000, Chambers  

>> <ben### [at] pacificwebguycom> did spake, saying:
>>> Air resistance might not apply, but manueverability does.  Applying 
a  

>>> force to different parts of the ship will stress different sections 
in  

>>> different ways.  That's a whole lot of differences there!
>>  Yes except what might be deemed 'travel' ships shouldn't be engaged 
in  

>> high stress producing maneuvers; those are reserved for the  

>> fighters/escorts/shuttles, which I agree need to be smaller.
>>
>>> Besides which, weight is out, but mass is in.  So smaller is still  

>>> better.
>>  No because a) although you need more oomph to get the ship  

>> moving/stopping that's a one-off cost
>
> It's a four-off cost.
> 1) Cost of materials to build a larger room

But like mass/volume the cost is not necessarily proportional to the vol
ume

> 2) More fuel needed to accelerate the additional mass
> 3) More fuel needed to decelerate (brake)
> 4) More fuel needed to carry the additional fuel for 2) and 3) above.

Except by default the mass of the fuel has to be less then the mass that
  

fuel can move and as I've already shown mass and volume are not  

proportionate.

>> and b) volume doesn't directly equal mass; if I increase the height o
f  

>> a room the only mass increase is in the walls and 'air'.
>
> While volume != mass, as your rooms grow in volume, the mass needed 
to  

> enclose them also grows.

No not really if you break it down to the simplest situation which is ju
st  

the one room, simply expand the room and section it. Okay the external  

walls may be thicker then the internal ones, but the principal stilll  

holds.

> It's not a linear relationship, but it is there.
>
>> Create a 7 unit cubic room with walls massing 1kg per square unit (al
l  

>> the same thickness). You're pumping it full of a gas that masses 0.1k
g  

>> per cubic unit. So the mass of the initial room is 328.3kg. Now  

>> increase the height of the room by 1 unit and you get 361.2kg a ~10% 
 

>> increase in mass for a ~14% gain in volume. Make it all 8*8*8 and you
  

>> get a ~49% volume increase for a ~32% mass increase.
>
> But what is that 32% mass increase is not feasible?  What if an  

> additional 10% isn't feasible?  This is a government funded project,  

> remember, and their budget is spread over many things - not just the r
ec  

> room for the astronauts.

No you're conflating feasible with cost, the budget that has been set is
  

simply someone's guess. If you look at almost any government project fin
al  

cost is always greater then initial budget, yet amazingly they've manage
d  

to locate the additional funds.

Now if you were saying "But we need to make these on Earth then transpor
t  

them up into space" then I'd agree that volume and mass are important.  

Before anyone mentions raw materials we're discussing 2001:ASO and if  

they're sending a manned spacehip out to Jupiter I'm betting they're  

mining asteroids.

>> Not that I'm saying 'Hey why not make all the rooms 300ft square' at 
 

>> some point you hit overkill, what I am saying is make the rooms the  

>> size they need to be for everyone to use them comfortably. So no duck
ing
>
> And the point was that it's not reasonable to just make it as big as y
ou  

> want; due to the (assumed) constraints, this is the ship that was  

> created.  A bit cramped, yes, but it gets the job done.

Except what I'm saying is there was no need for it to be "a bit cramped"
  

at all. Having a 300ft square bedroom is overkill, having a 7.5 cube  

instead of a 7 cube isn't.

-- 

Phil Cook

--
I once tried to be apathetic, but I just couldn't be bothered
http://flipc.blogspot.com

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