From: vitalmis@optusnet.com.au   
      
   Gordon D. Pusch wrote:   
      
   > Keith Harwood  writes:   
      
   >> Yup. Suppose, for example, such a material was used to make, say,   
   >> pressure vessles that mught contain such things as, say, rocket   
   >> propellants.   
   >   
   > For any reasonable strength of material, the amount of additional energy   
   > that can be stored by pressurizing the tanks is negligible compared to the   
   > chemical energy stored in the propellants themselves. About all you will   
   > do by pressurizing the tanks is to allow you to eliminate the mass of the   
   > turbopumps and drive turbines, which is likely to be marginal compared to   
   > the additional mass of high-pressure propellant tanks. Pressure-fed   
   > rockets _may_ be justifiable on the basis of lower cost or higher   
   > reliability, but are =VERY= unlikely to provide significantly better   
   > performance than pump-fed rockets.   
      
   I was thinking that the unobtainium that had sufficient tensile strength   
   with low mass to build a beanstalk could also be used to make pressure   
   vessels that are very much lighter than those from presently existing   
   materials and, indeed, would be lighter than existing unpressurised tanks.   
   My consideration was the mass savings from no pumps and from the tankage   
   itself. It hadn't occurred to me to even consider the energy stored in the   
   pressurisation.   
      
   My point was simply that the material that made the beanstalk feasible   
   compared to conventional rocketry would help make rocketry more competitive   
   against a beanstalk.   
      
   (PS, sorry about the deplorable typing my previous post.)   
      
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