text: NAVWEPS 00-8OT-80 
  AIRPLANE PERFORMANCE 
  
  cause the power required curve to flatten out 
  and move to higher velocities and powers 
  required. 
  
  The development of thrust by a turbojet or 
  ramjet powerplant is illustrated by figure 2.5. 
  Air approaches at a velocity, Vi, depending on 
  the flight speed and the powerplant operates 
  on a certain mass flow of air, Q, which passes 
  through the engine. Within 
  the powerplant 
  the air is compressed, energy is added by the 
  burning of fuel, and the mass flow is expelled 
  from the nozzle finally 
  reaching a velocity, 
  V;. The momentum change accomplished bv 
  this action produces the thrust,  The curves of thrust and power required and 
  their variation with weight, altitude, and con- 
  figuration are the basis of all phases of airplane 
  performance. These curves define the require- 
  lnent~ of the airplane and must be considered 
  with 
  the power and thrust available from the 
  powerplants to provide detailed study of the 
  various items of airplane performance. 
  
  Ttz=Q (V,V,) 
  AVAILABLE  THRUST AND  POWER 
  
  where 
  PRINCIPLES OF PROPULSION 