RE: FT3, details of needed changes

Oerjan wrote:

> On Tue, 24 Sep 1996, Samuel Penn wrote:
> 
> > 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...

Or 80%+ of the mass if we're talking about reaction drives, but
yes you're probably right - I just plucked two random figures
out of thin air for that example.

> 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?

There was some guy at NASA who had some research done on this,
and big rockets worked out cheaper and more efficient than
smaller ones. Of course, we're talking chemical rockets here,
but ion drives etc all work on the same principle - you apply
energy to some reaction mass, and chuck it out the back, so the
same theory should apply to all reaction drives (I would have
thought).

Of course, FT uses reactionless drives, which screws up everything.
It also uses shields heavily, which also causes complications.
Assuming armour though (shields are for wimps!), you're going to
be wanting as much of it as you can get away with. And it's mass
is going to go up with the square of linear dimension, while drive
volume will go up with the cube. So in theory, big ships end up
with a higher thrust/mass ratio.

Though as someone else pointed out, FT drives could work in any
way you damn well wanted, and end up being slower as they get
larger.

My feelings on the matter are that big ships should be fast,
but having them as slow lumbering hulks fits in with a lot of
science fiction much better.

-- 
Be seeing you,
Sam.