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Equation 1 · Part 2 · Flight at the Energy Floor: Transport Selection to 2100

Symbol a

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)
aa

What this part means

the local speed of sound.

Its job in the formula

a occurs above the fraction bar. The numerator is divided by the entire denominator below it.

Where the article explains it

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 ] .

The passage around this formula

Aircraft range is not a free parameter; it is fixed by a single classical relation once cruise speed, aerodynamic efficiency, and fuel fraction are set. In its standard Mach-number form, the range an 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…

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Learn the underlying idea

A variable is a named place for a value. Its letter is a local label: x can mean position in one formula and a data point in another.

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Sources cited in the surrounding passage

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