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Re: starship-design: my $0.02 (finally)

In a message dated 2/14/97 1:41:59 PM, lparker@cacaphony.net (L. Clayton
Parker) wrote:

>Hi Kelly,

hi, sorry about the delay.  To much overtime.

>I spent a few minutes talking to some physicists about this the other day
>(I'm an engineer). They managed to explain to me what it was and the
>difficulties inherent in tapping it. They all agreed that it would be a
>marvelous source of energy if it could be tapped, but as you pointed out,
>finding something colder (less excited) than 3 degrees is not going to be
>easy and without a gradient there would be no "spontaneous" emission of
>energy. Then there is still the problem of converting it into usable form.

This contradicts the articals and explanations I've heard.  The effect taps
the quantum action of spacetime in a vacume.  Some ways of taping it use
voltage beteen charged plates to alter the probabilities of spontaneous
emissions (and the speed of light).  The 'presure' on the plates between the
outside and the inside of the mechanism is tapable to produce energy.  Least
thats what the semi incomprehensiple explanation said was possible.  Could be
a fantasic source of high density power (on the order of nuclear densities
according to Forward), or it could be totally useless.

>I still think there has to be another source of external energy that can be
>tapped, harnessed or otherwise utilized for propulsion. The problem with
>all of the known methods of propulsion is that they require enormous
>amounts of energy to accelerate a starship to near light speed. In most
>cases this amount is so large that there is no reasonable chance that we
>can carry sufficient fuel or reaction mass to provide it directly.
>Since most of the discussion so far has revolved around specific
>technologies for GETTING THERE, I thought some consideration of general
>engineering design philosophies might be in order. Here are just a few of
>the key things to consider:
>1)	Minimum acceleration of 10 m/sec - Anything less would take too long to
>get there and expose 	the crew to a host of side effects. This simplifies
>design of the ship and eliminates the need 	for spinning habitat rings etc.
>More would be better, who knows what might come up.

More would be hard on the crew unless your talking a field effect drive or

You'ld need the hab centrafuge eiather way.  The ship does intend to park in
the star system for couple years after all.  Besides other then packing
effocencies it's not a big problem.

>2)	On board reaction mass must be either sufficient for the ROUNDTRIP or
>easily replaceable with on 	board resources. Don't forget a safety margin
>here also.


>3)	Engineering of the all systems (command, control, communications,
>environmental and 	propulsion) should be sufficiently simple to permit
>repairs and maintenance by the crew during the 	mission, or self repair
>ability should be built in (preferably both).


>4)	The propulsion system must be rugged enough to withstand continuous
>operation without major 	overhaul or replacement for a period equal to at
>least two and a half to three times the duration of 	the voyage. (Note that
>this almost automatically excludes most current technologies.)

This could be a problem.  We're pushing thrust to weight ratios pretty hard,
and need the drives to run for 20-30 years as it is.  Thats pretty much the
likly service life of the ship.  We may need to rely on relyability and
repairability (thou that might be a trick during drive operations.).

>5)	Manned exploratory missions must be roundtrip, colonization missions can
>be considered one way for purposes of design. But the mass of a colony
>ship will be corespondingly greater requiring an even more robust design.

Agreed.  In anyevent, we would be able to think of a real reason to put
colony somewhere until we new a lot about it anyway.  So colony missions, if
attempted, would be decades after the exploration flights.  By then our tech
assuptions would be completly obsolete.

>These are just some of the things that need to be considered prior to
>selecting a propulsion technology or method. Some methods are just plain
>impractical because they would never last through the trip, others fail to
>meet additional requirements. If I have duplicated previous conversations,
>please excuse this but I think it is more important at this date to define
>requirements before examining the technologies current or hypothesized that
>might fulfill them. If anybody has any additional thoughts or comments
>regarding things they think may be important in defining engineering
>requirements please feel free to post them.
>L. Parker

We did go around a bit on these issues before.  I think their was general