  We introduce SplitFlyer--a novel quadcopter with an ability to disassemble
into two self-contained bicopters through human assistance. As a subunit, the
bicopter is a severely underactuated aerial vehicle equipped with only two
propellers. Still, each bicopter is capable of independent flight. To achieve
this, we provide an analysis of the system dynamics by relaxing the control
over the yaw rotation, allowing the bicopter to maintain its large spinning
rate in flight. Taking into account the gyroscopic motion, the dynamics are
described and a cascaded control strategy is developed. We constructed a
transformable prototype to demonstrate consecutive flights in both
configurations. The results verify the proposed control strategy and show the
potential of the platform for future research in modular aerial swarm robotics.
