Comparing Planetary Helicopter Brownout Observations with Numerical Predictions for Ingenuity by D.-G. Caprace

With more than 70 successful flights, NASA’s Ingenuity helicopter demonstrated the feasibility of aerial exploration on Mars and opened the door to similar missions on other planets. Future planetary rotorcraft will be bigger and heavier to accomplish new scientific and exploratory goals. However, the flow induced by highly loaded rotors poses a risk of forming dust clouds during take-off and landing, a phenomenon known on Earth as brownout. We present an evaluation of 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 data recently gathered using image processing techniques of Ingenuity’s flights. 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 observation and the numerical.