text: flow is determined mainly by the shaft poluet 
  put into the propeller rather than thrust. Thus, 
  the powerplant fuel flow could be related di- 
  rectly to power required to maintain the air- 
  plane in steady, level flight. This fact allows 
  study of the range of the propeller powered 
  airplane by analysis of the curves of power 
  required versus velocity. 
  where 
  
  Figure 2.24 illustrates a typical curve of 
  power required versus velocity which, for the 
  propeller powered airplane, would be analo- 
  gous to the variation of fuel flow versus veloc- 
  ity. Maximum endurance condition would be 
  obtained at the point of minimum power re- 
  quired since this would require the lowest fuel 
  flow to keep the airplane in steady, level flight. 
  Maximum range condition would occur where 
  the proportion between velocity and power re- 
  quired is greatest and this point is located by 
  a straight line from the origin tangent to the 
  curve. 