text: the 
  and 
  time spent at high power 
  amount of total 
  setting, greater overhaul life of the powerplant 
  can be achieved. This should not imply that 
  the-takeoff rating of the engine should not be 
  the use of the full maximum 
  used. Actually, 
  power at takeoff will accumulate less total 
  engine wear than a reduced power setting at 
  the same RPM because of less time required to 
  climb to a given altitude or to accelerate to a 
  given speed. 
  
  fatigue damage. By minimizing 
  
  The final velocity of the propeller slipstream, 
  V,, is achieved some distance behind the pro- 
  peller. Because of the nature of the flow pat- 
  tern produced by the propeller, one half of the 
  total velocity change is produced as the flow 
  reaches the propeller disc. 
  the complete 
  velocity increase amounts to Za, the flow veloc- 
  ity has increased by the amount II at the pro- 
  peller disc. The propulsive e$icien~, vp, of the 
  ideal propeller could be expressed by the fol- 
  lowing relationship: 
  
  The most severe rate of wear and fatigue 
  damage occurs at high RPM and low MAP. 
  High RPM produces high centrifugal 
  loads 
  and reciprocating 
  loads. When the 
  iuertia 
  large reciprocating inertia loads are not cush- 
  ioned by high compression pressures, critical 
  resultant loads can be produced. Thus, op- 
  erating time at maximum RPM and MAP must 
  be held to a minimum and operation at mari- 
  mum RPM and low MAP must be avoided. 