Wing loading and aspect ratio
Wing loading is weight per unit of reference area, W/S. A light-airplane figure around 14–17 psf is typical of a Cessna 172-class wing; jet transports are much higher. Stall speed in level flight is
Vs = √( 2 (W/S) / (ρ CLmax) )
so, at a given CLmax and density, stall speed rises with the square root of wing loading. Aspect ratio AR = b²/S measures how slender the wing is. Higher AR generally means lower induced drag at a given lift (the induced-drag factor is proportional to CL² / (π AR e)).
Taper and mean aerodynamic chord
For a linearly tapered wing with taper ratio τ = ct/cr,
cr = 2S / (b (1+τ)), MAC = (2/3) cr (1+τ+τ²)/(1+τ).
A rectangular wing is the special case τ = 1, where MAC equals the geometric chord S/b.
Sources
NASA Glenn Beginner’s Guide (wing geometry, wing loading); Anderson, Introduction to Flight; FAA Pilot’s Handbook of Aeronautical Knowledge, Chapters 5 and 11. For stall speed versus weight and bank, see the stall speed calculator.
Frequently asked questions
What is a typical light-airplane wing loading?
A Cessna 172S-class airplane at 2,550 lb with about 174 ft² of wing has W/S ≈ 14.7 psf. Trainers are often in the mid-teens of psf; high-performance singles and twins are higher.
How is aspect ratio defined for a non-rectangular wing?
Still AR = b²/S, using the wingspan and the reference wing area. The induced-drag formula then includes an efficiency factor e that absorbs planform and twist departures from an ideal elliptic lift distribution.
What is mean aerodynamic chord used for?
MAC is the reference chord for aerodynamic coefficients and is the usual station for center-of-gravity limits (CG is often quoted in percent of MAC).