  A special type of rotary-wing Unmanned Aerial Vehicles (UAV), called
Quadcopter have prevailed to the civilian use for the past decade. They have
gained significant amount of attention within the UAV community for their
redundancy and ease of control, despite the fact that they fall under an
under-actuated system category. They come in a variety of configurations. The
"+" and "x" configurations were introduced first. Literature pertinent to these
two configurations is vast. However, in this paper, we define 6 additional
possible configurations for a Quadcopter that can be built under either "+" or
"x" setup. These configurations can be achieved by changing the angle that the
axis of rotation for rotors make with the main body, i.e., fuselage. This would
also change the location of the COM with respect to the propellers which can
add to the overall stability. A comprehensive dynamic model for all these
configurations is developed for the first time. The overall stability for these
configurations are addressed. In particular, it is shown that one configuration
can lead to the most statically-stable platform by adopting damping motion in
Roll/Pitch/Yaw, which is described for the first time to the best of our
knowledge.
