A

= stream tube cross-sectional area

= aspect ratio, b ²/ S

a

= speed of sound in air, ? ? RT; linear acceleration, d V /d t

b

= wing span

C _D

= finite wing or whole aircraft (three-dimensional) drag coefficient, D/q S

C _{D i}

= finite wing or whole aircraft (three-dimensional) induced (due to lift) drag coefficient

C _{D 0}

= whole aircraft (three-dimensional) zero-lift drag coefficient

C _{f e}

= equivalent skin-friction coefficient

C _L

= finite wing or whole aircraft (three-dimensional) lift coefficient, L/q S

C _M

= finite wing or whole aircraft pitching moment coefficient, M/q Sc

c

= wing or airfoil chord; specific fuel consumption used for reciprocating engines

c

= wing mean aerodynamic chord

c _d

= airfoil (two-dimensional) drag coefficient, d/q S

c _l

= airfoil (two-dimensional) lift coefficient, l/q S

c _m

= airfoil pitching moment coefficient, m/q Sc

c _t

= thrust-specific fuel consumption used primarily for turbine engines

c _root

= wing root chord

c _tip

= wing tip chord

D

= wing or aircraft total drag

D _i

= wing or aircraft induced drag or drag due to lift

D ₀

= wing or aircraft zero-lift drag

d

= airfoil drag

E _WD

= wave drag efficiency parameter, compares actual to ideal wave drag

e

= wing span efficiency factor

e _O

= aircraft Oswald's efficiency factor

F

= force

f

= airspeed compressibility correction factor

h

= altitude

i

= incidence...