From: del@branta.demon.co.uk   
      
      I'm playing with fantasy rockets for science fiction scenarios, and   
      I'm looking for some typical figures for rockets. What would you say   
      was a reasonable number for the following?   
      
   # volume flow rate   
      
      If an engine deals with a fluid having a density of 200 kilograms per   
      cubic metre and a mass flow rate of 400 kilograms a second, it would   
      have to have a volume flow rate of 2 cubic metres a second.  Is this   
      a reasonable number for a LOX/LH2 engine?  a LOX/kerosene engine?   
      
   # thrust to weight ratio   
      
      If an engine had a thrust of 1,800,000 newtons and a mass of 3,000   
      kilograms, it would have a thrust to weight ratio of 60, i.e. 600   
      newtons per kilogram.  Is this a reasonable number for a LOX/LH2   
      engine?  a LOX/kerosene engine?   
      
   # payload ratio   
      
      What would you say a reasonable ratio of payload to total initial   
      (i.e. fully-fueled) mass would be   
      
      a) for a two stage rocket   
      b) for a single-stage-to-orbit vehicle   
      
      (one percent?  five percent?)   
      
   # structure mass/tank volume ratio   
      
      Not counting the engine or the payload, what is a reasonable mass for   
      a stage containing x cubic metres of fuel, where the fuel is   
      a)LOX/LH2  b)LOX/kerosene  c)peroxide/kerosene?   
      
   # payload mass/volume ratio   
      
      For, say, a manned vehicle, how many cubic metres does a tonne   
      typically occupy?   
      
   --   
   Del Cotter   
   Thanks to the overwhelming volume of UBE, I am now rejecting *all* email   
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