From: g_d_pusch_remove_underscores@xnet.com   
      
   Philip  writes:   
      
   > EVD wrote:   
   >> I am going to describe something I saw on Discovery Wings and I hope you   
   >> can help identify it.  It was footage of an experiment that was not   
   >> fully described in the story on use of satellites to assist allied   
   >> soldiers in wartime.   
   >>   
   >> Here is what I saw.   
   >>   
   >> A device, which I can only describe as resembling an automobile   
   >> transmission, had what appeared to be 4 rocket exhaust nozzles mounted   
   >> around the circumference about mid-body pointing radially from the   
   >> centerline one at each 90 degrees (one pointing down, one up, one left,   
   >> one right).  There also appeared to be several much smaller rocket   
   >> nozzles at one end of device pointing away from the centerline.   
   >>   
   >> So now the experiment begins.  The video tape is running and you hear a   
   >> countdown.  At zero, the entire device (again, picture an auto   
   >> transmission with its long dimension oriented horizontally) leaps into   
   >> the air and hangs there in a hover as the rocket nozzle pointed down   
   >> fires in a pulsing fashion; looking almost like a machine gun muzzle.   
   >> The left and right pointing nozzles fire periodically as if to steady   
   >> the "aircraft" while the smaller nozzles at the end of the thing fire   
   >> smaller jets up, down, left, right to stabilize it.  Then as the rockets   
   >> all fire in a particular rapid sequence, the device rotates along its   
   >> length by 90 degrees in a roll and one of the nozzles that had   
   >> originally been pointing out to the side is now pointing down and it   
   >> takes on the role of being the primary provider of lift as it fires   
   >> spectacularly in a pulsing fashion.   
   >   
   > Sounds like a pulse detonation engine. But for hovering?   
      
   No, just a pulsed engine. (Hypergolic ACS thrusters are normally fired   
   in a series of short bursts, rather than continuously, because they are   
   usually radiatively cooled rather than regeneratively cooled, and also   
   because it is easier to achieve precise control via "pulsed" firings   
   than via a continuous burn.)   
      
      
   -- Gordon D. Pusch   
      
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