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Chapter 4

The Wing: Particulars of Flight

III CONTROL SURFACES
III WING DESIGN AND AERODYNAMICS
Modern aircraft are capable of in-fl ight modifi cation of
It’s a Plane
both their wings and tail sections. In the case of the
Imagine a teardrop, sliced in two lengthwise. The wing, leading edge slats and trailing edge fl aps can be

resultant object, curved edge up, flat edge down, blunt deployed to increase both width and camber, thus
end forward, and tapered end aft resembles the lateral increasing lift, which is required during takeoff and

profile of a classic airfoil or wing. This asymmetrical landing when air speed is greatly reduced (Figure 4-6).
shape causes the air moving over the upper and lower Trim tabs are also available to compensate for various
wing surface to exert a net upward pressure or lift, wind conditions. Recently, winglets (small fi ns situated
which combined with suffi cient forward thrust enables at the end of each wing) have been installed on many

flight. Weight and the force of gravity oppose lift. commercial airliners to improve their stall characteris-
Thrust is countered by drag. tics (Figure 4-7).
Some additional flight considerations exist. The Birds, however, are capable of innumerable fi ne, as

greater the wing surface, the greater the lift. The greater well as coarse, adjustments in their wings (Figure 4-8).

the thrust, the less the required lift; alternatively, the For the most part, the fi ne flight adjustments are
less the thrust, the greater the required lift. As the wing achieved by changing the configuration of the feathers

is tipped up (termed an increased angle of attack), lift along the wingtip, and in this respect, they far outdis-
increases but only to a point, at which time lift abruptly tance the capabilities of a static winglet.
decreases, causing the wing to stall, or cease to fl y. To give the reader a better understanding of the
Different wing shapes, or planforms, possess differ- complexity of a bird’s feathers and thus its control
ent aerodynamic qualities, with the elliptical wing surfaces, I have provided a series of photographs of a
most closely approaching the ideal for subsonic fl ight great horned owl with its wings fully spread. It is
(Figure 4-1). As aircraft become faster, their wings important to pay particular attention to the fi rst digit,

become smaller, flatter, more angular, and swept back also termed the alular digit or bastard wing, which the
to decrease drag (Figure 4-2). But fast comes with a bird deploys during flight to help counteract stall

price; namely, a need for greater thrust and superior forces (Figure 4-9).
fl ying skills, especially at low speed.
III TAILS AND RUDDERS
It’s a Bird
The wings of birds obey the same laws of physics as Most private, commercial, and military aircraft have
do those of airplanes but with far more sophisticated only a single tail fi n and rudder (Figure 4-10). However,
controls (discussed in a later section), although they there are exceptions, including the F-18 “Hornet,” with
are airfoils (Figure 4-3). Also, as with airplanes, the its aggressive V-shaped dual rudders (Figure 4-11), and
wings of birds come in different shapes with differ- the A-10 “Warthog,” which features a pair of very large

ent flight characteristics: elliptical, rectangular, wide, outboard fi ns (Figure 4-12).

narrow, short, long, slotted, and unslotted (Figures 4-4 Birds lack tail fins (vertical stabilizers) that provide
and 4-5). Unlike aircraft, the wings of birds provide positive directional stability on airplanes by increasing
thrust, as well as lift. Text continued on p. 53.
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