Brequet Range Equation                                            Vt=ti                                                   ...
This is the general form of the range equation. The Breguet range equation is                         V Lfound by assuming...
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Brequet range equation

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Brequet range equation

  1. 1. Brequet Range Equation Vt=ti t=tfW=Wi W=Wf Range tf Range = ∫ Vdt tiIn level flight at const speed: L = W , Lift = Weight T = D , Thrust = DragThe aircraft weight changes during flight due to use of fuel. Relate weightchange to time change: dW dW = dt dt fuel weight =− dt time fuel weight T =− dt time TThe quantity: fuel weight 1 time Tis known as the specific fuel consumption or sfc. It has units of: lb( fuel ) forcesfc units = or lb − hr force − time ⇒ dW = − sfc iT dt Wf V 1 ⇒ Range = − ∫ dW Wi sfc TBut since T = D and L = W we have: Wf V L dW Range = − ∫ Wi sfc D W16.100 2002 1
  2. 2. This is the general form of the range equation. The Breguet range equation is V Lfound by assuming that is constant for the entire flight. In that case: sfc D Wf Wf V L dW V L dWRange = − ∫ =− ∫ Wi sfc D W sfc D Wi WBreguet range equation: V L WiRange = log sfc D Wf

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