Loads and Stresses on the Mars Helicopter Ingenuity Rotor

The aeroelastic loads, stability, and stresses on the Mars Helicopter Ingenuity rotor were predicted during its design with a special-purpose three-dimensional rotor structural dynamic analysis. This paper documents that analysis and the insights gained from it. The thin and cold Martian atmosphere, with density 1% of Earth and speed of sound 30% lower, produced sufficient lift but unusually challenging dynamics even with one third the gravity of Earth. The aeroelastic stability was positive but low–about 10-50 times lower than Earth. The stresses and strains on the 5% thin carbon fiber blades were unsteady, complex, and three dimensional, but within material limits. The key conclusion was that the Ingenuity rotor was structurally stable and safe for Martian hover and controlled forward flight, even at the lowest Reynolds number and highest Mach number anticipated on Mars. Fundamental gaps in knowledge and tools remained, which must be addressed for larger, more capable rotorcraft in the future.