From: henry@spsystems.net   
      
   In article ,   
   Bill Bogen  wrote:   
   >How are thermal protection systems tested on the ground?  By directing   
   >superheated air at various temperatures, pressures, and durations to   
   >simulate a re-entry environment?   
      
   More or less, yes.  It's difficult to do entirely satisfactorily.  The   
   range of conditions is very wide and some of them are difficult to   
   reproduce on the ground.  Typically it's not too hard to reproduce *one*   
   condition, e.g. heating rate, but the combination is very difficult -- for   
   example, reproducing the heating rate with combustion heat will typically   
   give unrepresentative gas composition and properties.  So you use the best   
   simulation you can, or the best several simulations, and fill in the gaps   
   with some combination of theory, past experience, safety margins, and   
   crossed fingers.   
   --   
   "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)