From: henry@spsystems.net   
      
   In article <37bd12b7.0408111230.627cd407@posting.google.com>,   
   Steve Willner  wrote:   
   >A side question if you don't mind...  Henry also mentioned WFNA as a   
   >possible oxidizer.  Why is it superior to RFNA?  I seem to recall RFNA   
   >actually being used on some early rockets, but I don't think WFNA has   
   >been.  What makes one better than the other?   
      
   WFNA saw a very little bit of early use; not much.   
      
   Its advantages are:  it's a bit less corrosive; when you pour it, it   
   doesn't give off great clouds of extremely poisonous NO2.   
      
   Its disadvantages are:  its less-aggressive nature gives it slightly lower   
   Isp and makes it less hypergolic; even when it *is* nominally hypergolic,   
   that's often very sensitive to small amounts of added water (and given the   
   chance, it enthusiastically absorbs water from the atmosphere); it is   
   unstable and slowly turns itself into RFNA plus water.   
      
   It was considered interesting in the days when missiles had to be fueled   
   in the field (because good missile tank materials wouldn't stand up to   
   either WFNA or RFNA well enough for storage), because the lack of toxic   
   fumes was a big advantage.  People largely lost interest when John Clark's   
   lab discovered that adding a dash of hydrofluoric acid made RFNA far less   
   corrosive to well-chosen metals.   
   --   
   "Think outside the box -- the box isn't our friend."    |   Henry Spencer   
                                   -- George Herbert       | henry@spsystems.net   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)