Summary draft 2 of Helicopter Ingenuity Rotor Sub-system

In the publication, “Mars Helicopter Technology Demonstrator”, Balaram (2018) described the features of the rotor system of the Ingenuity.

The Ingenuity is equipped with a 1.21 m diameter coaxial counter-rotating rotor to minimize its size and constraints of its host aircraft. The rotor itself is designed with a rigid rotor to reduce flapping; that is the out-of-plane deflection the blades do when a force is applied.

The rigid rotor design is due to the thin Martian atmosphere which causes poor aerodynamic damping. Which causes altered the response of control inputs as well as cause the aircraft to oscillate during its flight phase. One drawback to the rigid rotor however, is being more vulnerable to gust.

To address the poor damping and at the same time allow some degree of flapping. The blades are unusually stiff, with a rotating flap frequency of about 80–90 Hz. The blades are able to flap at the outboard portion of the blades via elastic deformation.

The Martian atmosphere also requires the blades to spin at a maximum rotation of up to 2800 rpm. The bearings and swashplates are enclosed with seals and soft boots to prevent dust build up.

References

J. (Bob) Balaram, Timothy Canham, Courtney Duncan, Matt Golombek, Håvard Fjær Grip, Wayne Johnson, Justin Maki, Amelia Quon, Ryan Stern, and David Zhu. (2018). Mars Helicopter Technology Demonstrator https://rotorcraft.arc.nasa.gov/Publications/files/Balaram_AIAA2018_0023.pdf

*Edit 1: Improved clarity