Designing A Coaxial Quadrotor for Urban Air Mobility

The NASA Revolutionary Vertical Lift Technology Project has created several Urban Air Mobility reference design
vehicles to aid the burgeoning UAM industry. With over 700 conceptual designs already proposed, much interest has
been generated across many unique configurations to bring vertical flight to the masses. The quadrotor configuration
is one of the NASA reference vehicles, and does have some conceptual designs proposed in the industry. This study
looks at the conceptual design of a coaxial quadrotor vehicle as an extension of the NASA RVLT quadrotor concept
vehicle. The coaxial quadrotor has a similar layout to the quadrotor, but with a coaxial rotor at each of the four corners
of the vehicle. Trade studies carried out using the NASA Design and Analysis of Rotorcraft (NDARC) tool analyzed
the vehicle sizing, design gross weight, and performance for four design variants. The variants all use the baseline
coaxial quadrotor layout, but analyze the effects of two major design choices: 1) variable pitch vs variable speed rotor
control, and 2) motor to rotor power transmission via a gearbox vs direct-drive. The results indicate one design variant
may have more benefits on some of the design objectives while another configuration may better satisfy the others.