From: henry@spsystems.net   
      
   In article <20040203214210.28443.00001315@mb-m01.aol.com>,   
   Allen Meece  wrote:   
   >> To some extent this is a lingering echo of the idea that spaceships are,   
   >> or *should be*, just especially high-performance aircraft.  There has   
   >> never been any very strong justification for this belief, but it remains   
   >> an article of faith for many from the "aero" side of aerospace.   
   >   
   >The X-15 was "strong justification" for the  concept of a plane just going   
   >higher and faster until it's in orbit.   
      
   No more so than the SR-71, the X-1, or the Wright Flyer.  The X-15 was a   
   fast aircraft... where "fast" means about 25% of orbital velocity.  It had   
   little resemblance to an orbital vehicle, and provided no obvious   
   development path toward one.  Indeed, much of its design was strongly   
   driven by the requirement for high-speed flight *within the atmosphere*,   
   which is almost completely irrelevant to spaceflight.   
      
   This is just more faith-based wishful thinking.  The X-15 represents a   
   step along a path to aircraft-like spaceflight only if you believe such a   
   path exists.  It's the existence of the path that I am questioning.  The   
   performance gap between even the X-15 and an orbital vehicle remains vast,   
   and it's not at all obvious that there is any way to close it while   
   retaining the general characteristics of an aircraft.   
      
   Aircraft were not built by making cars or locomotives faster and lighter.   
   Spaceships will not be built by making aircraft faster and lighter.   
      
   Indeed, the single biggest problem of early spaceflight -- reentry -- was   
   solved only when Harvey Allen realized that a reentering spacecraft was   
   *NOT* an aircraft and should not be designed like an aircraft.   
   --   
   MOST launched 30 June; science observations running     |   Henry Spencer   
   since Oct; first surprises seen; papers pending.        | henry@spsystems.net   
      
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