text: RANGE AND ENDUR- 
  
  There are many conditions of flying oper- 
  ations in which optimum range or endurance 
  In 
  conditions are not possible or practical. 
  many instances, the off-optimum conditions 
  result from certain operational requirements 
  In 
  or simplification of operating procedure. 
  addition, off-optimum performance may be the 
  result of a powerplant malfunction or failure. 
  The most important conditions are discussed 
  for various airplanes by powerplant type. 
  
  RECIPROCATING  POWERED 