text: AIRPLANE TOTAL DRAG 
  
  I%,- rn+ql Jr,, nf ~ln eimlooe in fl.jght is the 
  AI&C CYCYl Y Ye v YIL L”y’““c 
  sum of the induced and parasite drag. Figure 
  toral drag 
  I.35 
  with speed for a given airplane in level flight 
  at a particular weight, configuration, and alti- 
  tude. The parasite drag increases with speed 
  varying as the square of the velocity while the 
  induced drag decreases with speed varying in- 
  versely as the square of the velocity. The 
  total drag of the airplane shows the predomi- 
  nance of induced drag at low speed and parasite 
  drag at high speed. Specific points of interest 
  on the drag curve are as follows: 
  
  In the subsonic regime of flight, the ordinary 
  configuration of airplane has a very large por- 
  tion of the equivalent parasite area determined 
  by skin friction drag. As the wing contrib- 
  utes nearly half of the total parasite drag, the 
  profile drag of the wing can be minimized by 
  the use of the airfoil sections which produce 
  flow. A subtle effect on 
  extensive laminar 
  parasite drag occurs from the influence of the 
  wing area. Since the wing area (S) appears 
  directly in the parasite drag equation, a reduc- 
  tion in wing area would reduce the parasite 
  factors were unchanged. 
  drag 
  While 
  involves con- 
  sideration of many factors, most optimum 
  airplane configurations have a strong preference 
  for 
  loading and 
  minimum wing surface area. 
  
  the highest practical wing 