Game Development Reference
In-Depth Information
will also help you quickly find what you are looking for when searching through the
references that we'll provide later.
First, take another look at the arrangement of our model aircraft in Figure 15-2 . The
main body of the aircraft, the part usually occupied by cargo and people, is called the
fuselage . The wings are the large rectangular lifting surfaces protruding from the fuselage
near the forward end. The longer dimension of the wing is called its span , while its
shorter dimension is called its chord length , or simply chord . The ratio of span squared
to wing area is called the aspect ratio , and for rectangular wings this reduces to the ratio
of span-to-chord.
In our model, the ailerons are located on the outboard ends of the wings. The flaps are
also located on the wings inboard of the ailerons. The small wing-like surfaces located
near the tail are called elevators . And the vertical flap located on the aft end of the tail
is the rudder . We'll talk more about what these control surfaces do later.
Taking a close look at a cross section of the wing helps to define a few more terms, as
shown in Figure 15-3 .
Figure 15-3. Airfoil section
The airfoil shown in Figure 15-3 is a typical cambered airfoil. Camber represents the
curvature of the airfoil. If you draw a straight line from the trailing edge to the leading
edge, you end up with what's called the chord line . Now if you divide the airfoil into a
number of cross sections, like slices in a loaf of bread, going from the trailing edge to
the leading edge, and then draw a curved line passing through the midpoint of each
section's thickness, you end up with the mean camber line . The maximum difference
between the mean camber line and the chord line is a measure of the camber of the
airfoil. The angle measured between the direction of travel of the airfoil (the relative
velocity vector of the airfoil as it passes through the air) and the chord line is called the
absolute angle of attack .