RE: starship-design: Pellet track

["L. Parker" <lparker@cacaphony.net>]

Just a general observation for everyone to think about...we are doing this 
backwards...

Kelly and Isaac were (are) having a conversation from which this is excerpted:

>>Assuming a .1% percentage, a rocket with a 10:1 thrust/weight ratio
>>and 1 millions sec Isp would be absorbing 10^12 watts/kg in waste
>>heat.  Without massive heat rejection systems (which would adversely
>>affect the thrust/weight ratio), that's going to melt the rocket in
>>a fraction of a second.

>>Therefore I don't consider the Bussard Votage compressions system
>>to truly offer a plausible chance at such high thrust/weight ratios,
>>considering how various components are directly impacted by fusion
>>products (thus implying a significant waste heat problem).

>Actually the Bussard system use anti-nutronic fuels that convert virtually
>all the power of the fusion reaction into the kinetic energy of the charged
>waste particals.  Efficency is about 99.9+%.  (give or take).  Most of the
>waste can just be vented to the sides.  

There is a great deal more, but the relevant parts have already been stated.

First, any sort of rocket propulsion capable of propelling a starship needs an
ISP of about 1 million give or take a few.
  
Second, any such propulsion system is going to generate waste heat.

Third, it is fairly likely that the total thermal gain to the ship is going to 
be significant, NO MATTER WHICH SPECIFIC DRIVE YOU USE.

Fourth, the ship will be subjected to this temperature continuously for extremely
long periods of time and will therefore also be subject to thermal and elastic 
fatigue.

There are no metals, alloys, ablatives, or EM fields currently available to deal
with this thermal gain. It will occur with fusion drives, plasma drives, photon 
drives and antimatter drives. It will even occur with Kyle's ZPE drive. So lets
reverse engineer this thing. Start by assuming a particular metal alloy for the 
skin of the ship, determine its melting point, divide by two for a safety margin,
now; what efficiency is NECESSARY in order to get an ISP of 1 million without 
exceeding the figure we just arrived at? Can we design a and build a drive to those
requirements?

Lee