From: fmccall@earthlink.net   
      
   pbreed@netburner.com wrote:   
      
   :Oribal velocity for LEO is about Mach 25 in the atmosphere....   
   :   
   :(list readers who really understand this don't ding me for simplifying the   
   velocity calcs   
   :the concepts are correct)   
      
   Well, no, they aren't.  Mach 25 WHERE in the atmosphere?  You need to   
   talk velocity and not airspeed related to pressure density (which is   
   what Mach number measures)   
      
   :A regular jet can get to mach 1 a specialized jet (SR-71) can get to mach 3   
   :beyond that the ai rfriction is so high things melt.   
      
   Not the problem, since rockets routinely go faster than that.  First,   
   'regular jets' can get up over Mach 2, depending on engine inlet   
   configuration.  Just look at the whacking big turbofans on an F-15.   
   The problem is that as you go past Mach 3 inlet design becomes   
   impossible for a conventional jet engine.  You can improve this by   
   changing the type of jet engine you're using and get up around Mach 8   
   or Mach 9, but this is difficult.   
      
   :A typical rocekt goes almost straight up until it is out of the atmpsphere   
   then it   
   :turns toward horizontal as it accelerates to orbital speed.   
      
   But if we're talking about people you also want to come back down.   
      
   --   
   "The reasonable man adapts himself to the world; the unreasonable   
    man persists in trying to adapt the world to himself. Therefore,   
    all progress depends on the unreasonable man."   
                                         --George Bernard Shaw   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)