From: schillin@spock.usc.edu   
      
   Reed Snellenberger  writes:   
      
   >Malcolm Street wrote:   
      
   >> John Schilling wrote:   
      
   >>Except, the core engine *only*, is showing a streak of bright   
   >>yellow down the center of the plume.  In this picture, but not   
   >>it others that I have seen.   
      
   >>I saw the same thing, firsthand eyewitness, during I believe   
   >>the penultimate RS-68 test at the AFRL/Edwards site.  About   
   >>three-quarters of the way through the test, the abrupt onset   
   >>of a yellow-streak flame in the plume, vanishing equally   
   >>abruptly a few seconds later.  So, a transient event, but not   
   >>a start or stop transient.  Consistent with it showing up in   
   >>the BBC photo but not all the rest, and now that we have a   
   >>photo I'm confident that it's real.   
      
      
   >It looks to me more like shock-wave interactions between the outboard   
   >plumes and the central plume.  The "streak" brightens and dims in a   
   >regular pattern, much like the shock diamonds in the exhaust from a   
   >single nozzle.   
      
      
   Except that A: shock diamonds are usually clearly visible when shocks   
   interact in such fashion, but aren't visible here, and more importantly   
   B: the same effect was observed in a test of a *single* RS-68 which   
   could not possibly have been participating in any multi-plume interaction.   
      
      
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