From: egruf_usenet@cox.net   
      
   On Sun, 16 Jan 2005 18:34:18 GMT, in sci.space.tech kenw@kmsi.net wrote:   
      
   >This is probably a dumb question, but...   
   >   
   >Would it be possible to use conventional jet engines to attain sufficient   
   >airspeed for scramjets to start to function?  SCRAMjets would seem to have   
   >limited value if they can only be launched via rocket.   
      
   Maybe. The problem is the relatively low speed achievable with today's   
   available turbines. The mean one must start the ram/scramjet somewhere   
   around Mach 2.5 or so. This is possible with the proper geometry. However,   
   this geometry will not then be correct for higher speed operation,   
   requiring some level of variable geometry.   
      
   There is some low level work being done looking at just this as the first   
   step towards proving the TBCC (Turbine Combination Combined Cycle) as a   
   follow-on to the now canceled BASA  X-43B program That program had as part   
   the development of the RTA (Revolutionary Turbine Accelerator) Mach 3.5-4   
   turbine.   
      
   >This obviously leads to issues like speed-tuning of SCRAMjet engine   
   >configurations, whether such engines can produce practical thrust levels,   
   >and whether there can be airframes that are useable over such a wide speed   
   >range.   
      
   For atmospheric cruise possibly. One of the secondary outcomes of the two   
   NASA X-43A test flights last year in addition to the on design scramjet   
   powered portions of the flights was the acquisition of high speed aero data   
   on this class of vehicle during the descent portion of the flights.   
   ----------   
   Ed Ruf    Lifetime AMA# 344007 (Usenet@EdwardG.Ruf.com)   
   http://EdwardGRuf.com   
      
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