Why a Coaxial?
The coaxial configuration is well-proven and has been used on full scale helicopters for decades. The Spirit provides a number of important advantages in mission-critical environments.
The coaxial reduces the airframe to the absolute minimum, resulting in a dramatic decrease in volume and weight.
Packs into a much smaller volume
Easier to transport where needed
Allows for launch and recovery points to be closer to the mission objective, reducing unproductive transit time
The cylinder is the simplest geometric shape that can be manufactured to be light and strong. For this reason it is used for many high-stress, low weight applications including gas storage, submarines and rockets.
The Spirit’s cylindrical design is inherently strong and also reduces much of the airframe’s complexity. The motor arms and all of the associated attachments, wiring and other components are eliminated. A simpler structure means:
Fewer parts and fewer points of failure before, during and after flight operations
Smaller spare parts inventory
Better Rotor Dynamics
Larger lifting surface: Spirit has more lifting surface than a conventional multirotor many times its size. For a comparable rotor area, Spirit’s airframe is a fraction of the size.
More adaptable rotor system: Increasing the length of Spirit’s rotor blades by just 1” creates nearly 20% more lifting surface with no additional airframe structure or weight. Increasing the rotor area on a conventional multirotor, however, requires longer motor arms, which in turn increases the overall size and weight and offsets some of the additional lift created.
Lower noise: Spirit’s rotors operate at a lower RPM, making it effectively inaudible at 100 meters.
Greater Payload Capacity
A coaxial’s compact airframe weighs half as much as a comparable multirotor.
A larger proportion of the overall weight is available for batteries and payloads
Fly longer and carry more
Spirit’s smooth cylindrical shape creates little form drag, and with no motor arms and other structures protruding into the airstream, Spirit is aerodynamically very efficient.
Lower power consumption
Better wind penetration