PPRuNe Forums - View Single Post - How is range increased when flying into a HW?
Old 10th Jul 2002, 07:26
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'%MAC'
 
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The general equation for ground range can be simplified into the self-apparent equation:

Rg = (V – Vw)/Q

Where V is aircraft TAS, Vw is wind speed, and Q is fuel flow rate. For a turbofan aircraft Q = cBW

c = a constant or if you want to get fancy it may vary proportionally to speed, something of say c -> V^.45 (for turboprops c is different)
B = Coefficient of Lift over drag
W = weight

As you can see, by maximizing the numerator we increase Rg. Since the Vw is independent of our TAS, if we increase TAS we increase the numerator and also the value of Rg. The problem is we are also increasing the fuel flow, but by a lesser ratio. (The equations can get a lot more fancy, but this should show the relationship fairly well.)

Last edited by '%MAC'; 10th Jul 2002 at 07:29.
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