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Equation 1 · Part 9 · Flight at the Energy Floor: Transport Selection to 2100

Symbol W_2

R=aMg cT⋅LD⋅ln⁡ ⁣(W1W2)R = \frac{aM}{g\,c_T}\cdot\frac{L}{D}\cdot\ln\!\left(\frac{W_1}{W_2}\right)
W2W_2

What this part means

W2W_2 occurs below the fraction bar. The quantity above the bar is divided by this expression; zero is excluded as a denominator.

Its job in the formula

W2W_2 occurs below the fraction bar. The quantity above the bar is divided by this expression; zero is excluded as a denominator.

The passage around this formula

…aircraft can fly in cruise is: R=aMg cT⋅LD⋅ln⁡ ⁣(W1W2)R = \frac{aM}{g\,c_T}\cdot\frac{L}{D}\cdot\ln\!\left(\frac{W_1}{W_2}\right). where a is the local speed of sound, M is cruise Mach number, g is standard gravity, cTc_T is thrust-specific fuel consumption, L/D is the lift-to-drag ratio, and W1W_1 and W2W_2 are the aircraft’s weight at the start and end of the cruise segment [ 1 ] . Three of those four factors — speed, engine efficiency, and aerodynamic efficiency — are where a century of aeronautical engineering has already done most of its work and where further gains now come in single-digit…

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A subscript is a label attached below a symbol. It often selects a time step, component, category, or member of a sequence.

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