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*To*: lparker@cacaphony.net, starship-design@lists.uoregon.edu*Subject*: Re: RE: starship-design: Pellet track*From*: KellySt@aol.com*Date*: Tue, 19 Aug 1997 00:10:55 -0400 (EDT)*Reply-To*: KellySt@aol.com*Sender*: owner-starship-design

In a message dated 8/18/97 4:25:11 PM, lparker@cacaphony.net (L. Parker) wrote: >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 Good point but a little misstated. The specific impulse isn't related to the heat load. And the question is what is the heat gain, and the wait of te cooling system. Kelly

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