2.11. CANTILEVER WINGS
Figure 2.11 shows a cantilever wing and a noncantilever wing. A cantilever wing has no external
supports and its structural strength is derived from its internal design. The advantage of this kind of
wing is it eliminates drag caused by wing struts. Its disadvantage is the added weight required to give
the wing its strength.
Figure 2.11. Cantilever and Noncantilever Wings.
2.12.
BOUNDARY LAYER
Figure 2.12, Boundary Layer Flow, shows laminar and turbulent flow and the transition point in
between. The boundary layer is the air close to the aircraft wings' upper surfaces. In the forward portion
of the boundary layer, the air flows in layers, or separate sheets, called laminae. These layers slide over
one another with little mingling of the air particles. However, behind the leading edge there is a
transition point where the layer thickens, the airflow becomes turbulent, and one layer mixes with
another. This results in increased drag. To aid in preventing boundary-layer turbulence, fences are
installed as shown in figure 2.13.
2.13.
SPEED BRAKES
Figure 2.14 shows an extended speed brake. These brakes are manually or hydraulically operated
flaps that project into the airstream. Generally, they extend from the sides of the aircraft. However, they
can
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