The promise of hypersonic flight

Ref: http://physicsweb.org/article/world/16/12/6
   
A hypersonic plane would reduce the time 
  taken to travel between any two places 
  on Earth to just two hours, but fighting 
  the forces of friction is pushing 
  aerodynamics to its limits.
  
See: http://physicsweb.org/article/world/16/12/6