From: henry@spsystems.net   
      
   In article <45022fc8.0401121621.5a128818@posting.google.com>,   
   Iain McClatchie  wrote:   
   >Suppose the propellants are not hypergolic.  Why not mix them, then   
   >burn them, more like a bunsen burner?   
      
   Provided you can arrange for both to be gases at the time, there is some   
   merit to this... although there is also some risk of explosion.  (People   
   did experiment with premixing injectors for *liquids*, and gave up on the   
   idea because it tended to make brief unexpected loud noises. :-))  Bunsen   
   burners run at rather lower pressures and densities...   
      
   >To capture the flame, I'd use a tube that flares, perhaps with wires   
   >crossing it to form a flameholder (and to provide initial ignition).   
      
   Note that the function of a flameholder is partly to induce turbulence,   
   which somewhat defeats your intent.  Gaseous fuel mixes burn much faster   
   if you stir some of the combustion products back into the incoming mix;   
   it's thought that they catalyze otherwise-slow steps in the combustion   
   process.   
      
   >Advantages:   
   >  - Less noisy   
      
   If (dim) memory serves, rocket noise is thought to be more a function of   
   the supersonic exhaust jet hitting air, than of the process in the   
   chamber.   
      
   >How thermodynamically efficient is accelerating a boiling two-phase   
   >mixture?  My guess is that boiling the propellant in the combustion   
   >chamber is not critical to efficiency, since the SSME injects   
   >gas-phase hydrogen.  Perhaps higher-temperature methane, propane, and   
   >oxygen are a different story.   
      
   People have run RL10s on methane and propane without difficulty, using   
   the same basic injection strategy (gaseous fuel, liquid oxidizer).   
      
   There is little experience with gas/gas injectors in rockets, though.   
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   MOST launched 30 June; science observations running     |   Henry Spencer   
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