Planetary Helicopter Brownout Simulation of Ingenuity Using a Eulerian Dust Transport Model

Ingenuity has sustained an astonishing 72 flights on Mars. The small helicopter proved that nonterrestrial powered flight is possible, even on planets with thin atmospheres. Future planetary rotorcraft will be bigger and heavier to accomplish new scientific and exploratory goals. For example, the Dragonfly mission will send a rotorcraft the size of a regular car to explore Titan. However, on dusty planets, the increase in rotor thrust due to increased weight poses a potential challenge. Dust clouds could form during takeoff and landing due to rotor wash, a phenomenon referred to as brownout. This work evaluates the effectiveness of existing numerical simulation models in predicting the severity of this phenomenon for planetary rotorcraft. We compare the output of a CFD-based dust mobilization model with Ingenuity flight data gathered using image processing techniques. The simulation results suggest that the sensitivity of the wall friction velocity to the rotorcraft height may be lower than previously assessed. We further evaluate the sensitivity of the total mass of mobilized dust to other model parameters such as the sandblasting efficiency and the saltation threshold velocity. Finally, we discuss the limitations of this comparison due to uncertainty in both the observational and the numerical model.