text: knots requires one horsepower of propulsive 
  power. However, each pound of drag at 650 
  knots requires two horsepower while each 
  pound of drag at 162.5 knots requires one-half 
  horsepower. The term “power” 
  implies work 
  rate and, as such, will be a function of the speed 
  at which a particular force is developed. 
  
  between thrust required and 
  pawcr required is necessary for several reasons. 
  For the items of performance such as range and 
  endurance, it is necessary to relate powerplant 
  fuel flow with 
  the propulsive requirement for 
  steady IeveI flight. Some powerplants incur 
  fuel flow rate according to output thrust while 
  other powerplants incur fuel flow rate depend- 
  ing on output power. For example, the turbo- 
  jet engine is principally. a thrust producing 
  machine and fuel flow is most directly related 
  to thrust output. The reciprocating engine is 
  principally a power producing machine and 
  is most directiy reiated to power 
  fuei flow 
  output. For these reasons the variation of 
  thrust required wil1 be of greatest interest in 
  the performance of the turbojet powered air- 
  plane while 
  the variation of power required 
  will be of greatest interest in the performance 
  of the propeller powered airplane. Also, dis- 
  tinction between power and thrust required is 
  necessary in the study of climb performance. 
  During a steady climb, the rate of climb will 
  the angle of 
  depend on excess power while 
  climb is a function of excess thrust. 
  
  Distinction 