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Chapter 2: Quadcopter Flight Dynamics 15

Figure 2.2 Airplane principal axes and axial rotation motions.

rotational motions associated with each of these axes are also shown in Figure 2.2 and are
described in Table 2.2.
Actual flight path turns are a combination of coordinated roll and yaw rotations that
result from pilot initiated motion of both the aileron- (the hinged surface at the edge of an
airplane wing) and rudder-control surfaces. Figure 2.3 shows the three rotational motions
and the corresponding axes as they apply to a quadcopter. The quadcopter diagrammed in
the figure is in an X configuration, which is discussed in the next section. However, it makes
no difference how a quadcopter is configured; the pitch, roll, and yaw rotational motions
will always be the same for each axis.
Basic Quadcopter Configurations
The basic quadcopter is simply a center platform from which booms are extended. Motors
with propellers are attached at the end of each boom. A variety of configurations exist based
upon this basic form. Some of the most common are shown in Figure 2.4.
The configuration shown at the top left of the figure is the plus configuration, while the
top center is the X configuration. The X configuration is the type used in the Elev-8. The only
difference between the plus and X configurations is the forward direction designation. The
forward direction is always aligned with a boom for the plus, while it is centered between
two booms for the X configuration. It is imperative that the actual quadcopter configuration
be input into the flight-control board, or else it will not be able to properly control the copter.

Name Axis Description
Pitch Lateral Rotation around the lateral axis that results in a climb or
descent
Roll Longitudinal Rotation around the longitudinal axis that results in straight line
roll but no turn to either side
Yaw Vertical Rotation around the vertical axis that results in a turn to the left
or right

Table 2.2 Aerodynamic Rotational Motions