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Re: starship-design: Re: Re: regarding fuel expenditures

L. Parker wrote:
>On Friday, November 14, 1997 4:41 PM, KellySt@aol.com 
>[SMTP:KellySt@aol.com] wrote:
>> You really don't need to do the sligshot manuvers around Earth and the
>> Sun.
>>  A star Ship needs such powerfull engines, and has to boost to such high
>> speeds, that the gains from these manuvers are a joke.

>Not quite true, that particular orbital maneuver has already been 
>researched thoroughly, we have even discussed it here.A

That's not the point.  The point is that the potential extra benefit
is a ridiculously small amount compared to a percent of c in delta-v.

In fact, the disadvantages are such that they overwhelm any advantage.

>It is called the 
>"Powered Perihelion Maneuver" and is capable of generating up 400 g's of 
>thrust initially. The drawback of course is that this thrust is more than a 
>human can withstand and that it tapers off as your course takes you further 
>from the sun.

Even without the human limitation, strengthenning an unmanned probe
for 400 g's will increase its mass by at least some small fraction.
This will make it require _more_ fuel, not less.

>Due to human limitations, the highest cruise velocity obtainable without 
>further boost from some other sort of engine is only 0.003 c. Something 
>akin to Forward's Starwisp on the other hand, could be accelerated to over 
>0.3 c in only a few days and even faster using a combination of this 
>maneuver and follow on beamed power from an orbital power satellite.

It would not be significantly faster.  And that's the point.
    _____     Isaac Kuo kuo@bit.csc.lsu.edu http://www.csc.lsu.edu/~kuo
/___________\ "Mari-san...  Yokatta...
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