text: where 
  
  D,,= parasite drag corresponding to some orig- 
  
  inal parasite area, fi 
  
  D,,==parasite drag corresponding to some new 
  
  parasite area, fi 
  
  (V and (r are constant) 
  D,,=parasite drag corresponding to some new 
  
  speed, VS 
  
  As an example, the lowering of the landing 
  gear and flaps may increase the parasite area 
  80 percent. At any given speed and altitude 
  this airplane would experience an 80 percent 
  increase in parasite drag. 
  
  This relationship expresses a powerful effect 
  of speed on parasite drag. As an example, a 
  given airplane in flight at some altitude would 
  have four times as much parasite drag at twice 
  In a similar man- 
  ner the effect of altitude on parasite drag may 
  
  EFFECT OF ALTITUDE. 
  
  91 