RE: FT3, details of needed changes

On Tue, 24 Sep 1996, Samuel Penn wrote:

> > Hm. Doesn't the 'output increases as square, mass increases as cube'

> > apply to starships...?
> 
> But volume increases with the cube of linear dimensions, and surface
> area increases with the square.
> 
> Mass of hull and armour increases slower than the amount of mass
> that can be invested in drives. 25% volume of drives on a small
> ship might equate to 25% mass, but on a big ship to only say 10%
> mass. So your thrust to mass ratio has just gone up, so the ship
> is 'faster'.

Uh - no, more likely the other way round, unless your engines are 
considerably lighter than most weaponry! I'd rather say that engines 
equates 10% of the volume but 25% of the mass...

While ship masses don't necessarily increase by the cube of the length
scale, it does (approximately) if you fill the extra volume with
additional equipment - like engines, weapons, shields etc. Of course, a
troop transport will have lots of empty space inside rather than
weapons...

Furthermore, the bigger ships need stronger structural supports if they
are to be able to manouver as fast as smaller ships, which increases the

mass even more.
 
> This factor is reasonably easy to discover if you use vaguely
> realistic ship creation rules.

What is realistic depends on your assumptions about engine masses, of 
course. As long as we use standard rocket drives, we can make 
reasonable assumptions, but what about ion engines? Photon drives?
Whatever?

> It's also the case that big drives tend to be more efficient. If
> they're not, you just use lots of small drives to get the same
> efficiency as small drives.

Unless, of course, you lose more trying to make the smaller engines
cooperate than you do by increasing the scale. I know too little 

> Hence, big ships are faster. It's counter intuitive to what people
> are used to based on the ground, but there's no friction in space
> which increases with the size of the ship (as you have in an
> atmosphere).

Oerjan Ohlson

"Father, what is wrong?"
"My shoes are too tight. But it does not matter, because
 I have forgotten how to dance."
- Londo Mollari