text: operational factors will define operating pro- 
  cedures. 
  
  RANGE, TURBOJET AIRPLANES. Many 
  factors influence the range of the 
  different 
  the 
  turbojet airplane. 
  analysis of the overall range problem, it 
  is 
  convenient to separate airplane factors from 
  powerplant 
  factors and analyze each item 
  independently. An analogy would be the 
  study of “horsecart” performance by separat- 
  per- 
  ing “cart” 
  formance to distinguish the principal 
  factors 
  which affect the overall performance. 
  
  The effect of the variation of airplane gross 
  is illustrated by the second graph 
  weight 
  condition of 
  flight 
  of 
  1 D IMI is achieved at one value of lift 
  (mc 
  coefbcient for a given airplane in subsonic 
  flight. Hence, a variation of gross weight will 
  alter the values of airspeed, thrust required, 
  and specific range obtained at ,(&/CD)-. 
  If 
  a given configuration is operated at constant 
  altitude and lift coefficient the following 
  lationships will apply: 
  
  In the case of the turbojet airplane, the 
  fuel flow is determined mainly by the thrust 
  rather than power. Thus, the fuel flow could 
  be most directly related to the thrust required 
  to maintain the airplane in steady, level flight. 
  .This fact allows study of the turbojet powered 
  airplane by analysis of the curves of thrust 
  required versus velocity. Figure 2.25 illu- 
  strates a typical curve of thrust required versus 
  velocity which would be (somewhat) analo- 
  gous to the variation of fuel flow versus veloc- 
  ity. Maximum endurance condition would 
  be obtained at (L/D)- 
  since this would incur 
  the lowest fuel flow to keep the airplane in 
  steady, level flight. Maximum range condition 
  would occur where the proportion between 
  velocity and thrust required is greatest and 
  this point is located by a straight line from 
  the origin tangent to the curve. 
  thrust 