Page 33 - Aerodynamics for Engineering Students

16 Aerodynamics for Engineering Students

Wing span
The wing span is the dimension b, the distance between the extreme wingtips. The
distance, s, from each tip to the centre-line, is the wing semi-span.

Chords
The two lengths CT and co are the tip and root chords respectively; with the alter-
native convention, the root chord is the distance between the intersections with the
fuselage centre-line of the leading and trailing edges produced. The ratio c=/c0 is the
taper ratio A. Sometimes the reciprocal of this, namely co/c~, is taken as the taper
ratio. For most wings CT/Q < 1.

Wing area
The plan-area of the wing including the continuation within the fuselage is the gross
wing area, SG. The unqualified term wing area S is usually intended to mean this
gross wing area. The plan-area of the exposed wing, i.e. excluding the continuation
within the fuselage, is the net wing area, SN.

Mean chords
A useful parameter, the standard mean chord or the geometric mean chord, is
denoted by E, defined by E = SG/b or SNIb. It should be stated whether SG or SN is
used. This definition may also be written as

where y is distance measured from the centre-line towards the starboard (right-hand
to the pilot) tip. This standard mean chord is often abbreviated to SMC.
Another mean chord is the aerodynamic mean chord (AMC), denoted by EA or E;
and is defined by

Aspect ratio
The aspect ratio is a measure of the narrowness of the wing planform. It is denoted by
A, or sometimes by (AR), and is given by

span b
SMC - :
A=--