Re: Engineering Newsletter

[KellySt@aol.com]

> 
> to:  Rick
> >
> >
> >>> Now, is there any thing at AC worth going there for?
> >
> >Is there anything in Tau C?  You got a problem with multiple star systems
or
> >something?
> >
> >Kelly
> 
> I have no problem with multi-star systems but will they support
> planets that would be stable for life? And you are right, Is there
> anything at TC worth going to either.

Who knows?  We have no idea what areas life can handel.  If nothing else a
very different starsystem could answer a lot of questions, especiall with
three stars of different types.  Of course we'ld know where the planets were
before we sent of the mission.

> The problems is were we live, and probably true for space as a whole, with
> few stars "close" to us. The problem of living in a spur of a sprial arm,
> kind of out of the mainstream. Like being in a town that the Intestate
> jogged around. :-)

Unfortunatly, this is an unusually empty area of space.  Both in starsystems
and in interstellar matter.


> 
> To Timothy:
> 
> >stage  total weight (tons)     thruster pack and stage structure
> >1      1,000,000,000           10,000,000 
> >2         40,000,000              400,000  
> >3          2,000,000               70,000 ton ship 
> >                                 with 5-10,000 tons of 
> >                                  drive systems. 
> >
> >This assumes a 100 to 1 thrust to weight ration for a fussion drive
systems
> >(which is questionable), and once you get where your going, coming back is
> >out.  But it would give us huge fuel ratios for relativistic flight.
> > Possibly a multi stage fusion craft to get to the star and build a fuel
> >launcher systems for two way flight?  I'll have to think on this.
> 
> I assumed that we could build a variable thrust engine, but for
> weight-savings staging may be better.

Yes, the weight of the huge engines we'ld need at the start would dominate
the ship after a little while.

> I think that staging would not solve a more fundamental problem: Pressure
> One can see the engine as a force pressing on the back of the ship. We want
> a certain acceleration a. The heavier the ship gets, the bigger the force
> that is needed to get that acceleration (F=m*a). But assuming the backside
> of the ship stays about the same, the pressure (p=F/Area) gets bigger and
> bigger. ---

Do you mean the thrust loads?  If so we will need to take that into
consideration.  But we can use some of the fuel or reaction mass as structure
(ice perhaps?) and the structure needed to carry the load shouldn't be a
major fraction of the fuel mass.

> 
> >>                      *       LIT "ASIMOV"      *
> >>                      *     Starship Design     *
> >
> >You might have noticed I hate the name Asimov for the ship.  It gives the
> >whole project a grade school feel.  I mean lets be real.  This is a name
that
> >would never be acceptable to a real starship project.
> 
> I never liked it much either, I guess the vote was done by passer-by-ers on
> the Web. I can recal that I added the optimistic name 'New Eden' :)
> What did you vote Kelly?

I never even heard their was a vote until the 'winner' was announced.  Thou I
guess since I picked Explorer for my design, that would count as a vote.

> >>    * Manned:
> >>      * Without crew procreation
> >>        * Suicide (explore and die before your time when supplies end)
> >>        * One-way (outpost construction and stay till natural death)
> >
> >Suicide and one way are the same.  We couldn't biuld a self sustaining
> >outpost, and wouldn't fund resupply flights forever unless there was
> >something in it for us (or a fantastic improvement in star drives back
home).
> > NO ONE would fund a one-way flight.
> 
> I don't agree with you on that (yet?), I will expect an answer on
> my letter of 01-05 10:55.

What letter?  The ones in my inbox don't have that time?

Given that fantastic trouble NASA has always had justifing risking people in
space.  The idea of deliberatly sending them to their deaths is ludacrus!
 Every politician who ever came near you would rush to lead the witch hunt to
fire you and anyone who ever asked you a question.  Any public interest in
the project would immediatly turn to revulsion at such a suggestion.  The
whole concept of interstallar flight would be off limits for years, even if
someone else came up with a two way idea.

> >>      * Use the interstellar medium
> >
> >We have no real idea how to, or for that matter know whats out there to
use.
> 
> There is just too little, unless we can scoop an area with a 1000 km
radius.

Again we don't even know whats out their, but it does seem unlikly that it
will be able to help us any.

> >>      * Power from installations at Solar system
> >
> >Beamed power or fuel launchers have the advantage of offloading the need
to
> >carry the heavy fuel (and power systems) with the ship.  That improves the
> >ships power to weight ration significantly.  But the systems are difficult
to
> >do, limit range, and don't seem to help us to slow down.
> 
> Also they have a not so good efficiency. (A big part of the beam just flies
> along the ship without being used.)

Thats true of beamed power, not launched fuel.

> >> 3. Gravity on board
> >
> >I think the idea I came up with for a multi segmeny hab ring is the best.
 We
> >need gravity for the crew, and the rotating hab segments will allow it to
> >adapt to changing thrust directions.  Unless the ship can operate under
> >continuous thrust for the full flight.  This seem best.
> 
> You would always need the rotating rings, because in the time that you
spend
> at TC you don't have acceleration because of engine-thrust.

True.  I guess my had ring idea covers all requirement well enough to be
assumed in a ship.

> >> 4. Mission composition
> >
> >Given the size the main ship must be, I don't think we could afford 2.
 Which
> >is a pity from a safty standpoint.  A robotic pathfinder would be a good
idea
> >if it would work, but I'm dubious.  
> >
> >A suply ship sounds a little risky.  How would you like to be waiting in
the
> >target system for the next 5 years groceries.
> 
> The idea of supply ships is to send them first and wait for them to arrive
> savely, unfortunately that would take 20 years from their launch. No a good
> way for food. 

20 year old rations?  <yuck!>

Kelly