XPost: sci.space.shuttle, sci.space.history, rec.aviation.military   
   From: joe@nospam.invalid.retro.com   
      
   "tomcat"  wrote in message   
   news:1139620100.837895.302360@z14g2000cwz.googlegroups.com...   
   >   
   > Wings use air to gain an advantage on gravity.  Therefore, they can   
   > reach the airless void using less energy than a vertical tublular   
   > rocket.   
      
   The goal isn't getting to orbit using the least energy -- it's   
   getting to orbit the cheapest, safest way. The energy expended   
   by a rocket is often inexpensive LOX and LH2. LOX is virtually   
   free and LH2 is a very low % of operating costs.   
      
   It makes no sense using a tremendously complicated,   
   very expensive hypersonic airbreathing winged vehicle to save a   
   few dollars of propellant.   
      
   >   
   > The proof that wings gain an advantage is that a bomber can reach   
   > 20,000 feet and stay there for the hours it takes to reach target and   
   > return on 1/10th of the thrust to weight ratio that a vertical tubular   
   > rocket requires just to slowly leave the launch pad.   
      
   This only illustrates that jet engines have much better specific   
   fuel consumption than rockets. The B-52H TF33 jet engine   
   has a specific fuel consumption of about 0.56 lb fuel per   
   pound thrust per hr. The shuttle SSME consumes about 9.4   
   lb propellant per pound thrust per hr.   
      
   A rocket can produce lots of thrust, but its specific propellant   
   consumption is poor. It's better to let the rocket do what it does   
   best -- produce lots of thrust and get out of the atmosphere   
   quickly. Wings just slow you down.   
      
   If you replaced the B-52's jet engines with rockets, it couldn't   
   fly for hrs, despite having wings. It's not the wings that make   
   the difference, it's the engine type.   
      
   >   
   > In short, you have to get from here to orbit and the best method is a   
   > winged or waverider vehicle.   
      
   The best way is the cheapest, most reliable way. Cheap means   
   a combination of operating costs and development costs.   
   Nobody gives you an award for getting to orbit the most   
   romantic way, or the coolest way.   
      
   > The airfoil vehicle, however, is more   
   > difficult to design than a vertical tubular rocket.   
      
   You've got that part right. A winged hypersonic airbreathing   
   orbital launcher is so difficult nobody has figured out how to   
   do it.   
      
   >   
   > a waverider design shouldn't be all that difficult with   
   > the knowledge and materials base that exists in 2006.   
      
   Add about a hundred years to that and you're closer to   
   correct.   
      
   > And, slush hydrogen tanks have   
   > solved the volume problem for hypergolic hydrogen/lox burners like the   
   > SSME.   
   >   
   Hydrogen/LOX engines are NOT hypergolic.   
      
   -- Joe D.   
      
   --- SoupGate-Win32 v1.05   
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