text: where 
  
  condition (I) applies to some known condi- 
  tion of velocity and power required for 
  W’),,,,,z at some original, basic altitude 
  condirion (2) applies to some new values of 
  velocity and power required for (L/D),, 
  at some different altitude 
  
  and 
  
  V= velocity, knots (TAX, of course) 
  Pr=power required, h.p. 
  o=altitude density ratio (sigma) 
  
  Thus, 
  (o=O.498), the airplane will have: 
  a 42 percent higher velocity 
  a 42 percent higher power required 
  
  if  flight  is conducted at 22,000 ft. 
  
  than when operating at sea level. Of course, 
  the greater velocity is a higher TAS since the 
  airplane at a given weight and lift coefficient 
  require the same PAS independent of 
  will 
  altitude. Also, the drag of the airplane at 
  altitude is the same as the drag at sea level but 
  the higher TAS causes a proportionately 
  greater power required. Note chat the same 
  straight line from the origin tangent to the sea 
  level power curve also is 
  the 
  altitude power curve. 
  
  tangent  to 
  
  The effect of altitude on specific range can be 
  appreciated from 
  the previous relationships. 
  If a change in altitude causes identical changes 
  in velocity and power required, the proportion 
  of velocity to power required would be un- 
  changed. This fact implies that the specific 
  range of the propeller powered airplane would 
  be unaffected by altitude. 
  In the actual case, 
  this is true to the extent that powerplant specif- 
  ic fuel consumption (c) and propeller efficiency 
  factors which could 
  (qp) are the principal 
  cause a variation of specific range with altitude. 