Re: RE: starship-design: Modular Ship Design

[KellySt@aol.com]

Kelly,



> -----Original Message-----

> Since I had a centrafuge with rotating segments.  The floor's can

> move to the

> sides front or rear as nessisary. Or for that mater you could

> just flip the

> hab segment over as you restack the modular ship?



Flipping the whole hab was pretty much the way I saw it too, it is just the

idea of doing this in flight at a significant fraction of light speed which

bothers me.

Actually I think the hab centrafuge ring makes more sence.  After all the ship
will have to spend its time at varing accelerations as it burns off fuel, and
zero G as it floats in the target system.  These can't be delt with by a fixed
hab floor no mater how much you flip it.


> By picking Lithum-proton as a fusion fuel, I figured we could do

> without tanks

> at all since the fuel is a structural metal.  So the drive system is

> effectivly a tug pushing a huge (or small depending) solid block of metal.

> Wrap yourself in it for shielding, stack it in frount for easy

> shoving, maybe

> even use it for structural supports.



It would probably need to be pelletized before it could be sent into the

reactor/engine. Just as easy to build a giant tank and fill it full of

lithium pellets.

A lithium block can be cut and pressed into pellets, but a mile long tank of
pellets would be a serious structural problem under acceleration.



> I don't worry as much about burn time limits, but with the fuel

> carry limits

> we have a prett much fixed upper speed limit.  I'ld rather get to

> it quickly,

> not speed half the flight geting to speed.



I don't see this at all.



Given:



Scenario A    Scenario B



1 G thrust    1 G thrust

3 month burn   3 year burn



Then delta v of Scenario A is less than delta v of Scenario B, and

total trip time of Scenario A is greater than Scenario B.



The only constraining factor is can we carry sufficient propellant to

maintain continuous thrust? (There is also the little problem that B

requires more engine than A as well...)

You missed the part of my statement about fuel constraint.  A given weight of
fuel, only has the energy to accelerate the ship to a given delta-V.  It
doesn't make much difference (speed wise) if it burns all the fuel quickly, or
slowly.  So I figure at 1 g my fusion systems could get you about 4-5 months
of total thrust.

If we didn't have the fuel/delta-V limitation then a continuous 1-G burn for
the flight would be great. In about a year you'ld be presses light speed, and
Alph-C would be under 3 years away ship time. But we don't have that kind of
power.

Given we haven't come up with anyway other then fusion that we could really
decelerate into or out of the target system.  (I'm very dubious about anti-
matter, and the limited details of its control and use I've heard.)  We're
limited by the credable delta-V a fusion powered drive can give us.



Lee Parker

Kelly