Investigating bumblebee-esque micro air vehicles in the Martian atmosphere

Micro air vehicles (MAVs) with flapping wings are well-suited for exploration on Mars, where viscous forces dominate over inertial forces in the atmosphere. However, the low density of Mars’s atmosphere might make it difficult to operate small MAVs. The atmosphere’s low density leads to the vehicle experiencing the rarefaction effect, in which the slip velocity of gas occurs along the aircraft body surface, as well as the compressibility effect, in which variations in the gas’ density cause gas flow and behavior changes of MAVs.

Both can affect the performance of MAVs, but it’s unclear exactly how. With numerical simulations, Widdup et al. assessed the influence of the rarefaction and compressibility effects on the aerodynamic and acoustic performance of a bumblebee-inspired MAV. They found rarefaction improves the lift by decreasing the viscous force, while compressibility reduces the lift.

These results will inform the design of flapping-wing MAVs for Mars exploration by allowing appropriate scaling of Earth-based designs. Typically, researchers rescale the aerodynamics forces only using the density difference of the two planets, but these results show that compressibility effects should be considered as well.

“This sets a foundation for new aerodynamic research and control strategies in flapping-wing MAVs in space and planetary exploration,” said author Fang-Bao Tian. “There is a huge aerodynamic potential for exploring novel control strategies to maintain the high lift force, which we are currently working on.”

In addition to investigating methods for maintaining lift, the authors plan to extend the numerical techniques used in this work to design control strategies for other types of supersonic or hypersonic crafts.

Source: “The aerodynamic and acoustic performance of a bumblebee-inspired micro-air vehicle in Martian atmosphere,” by Nathan Widdup, Li Wang, John Young, and Fang-Bao Tian, Physics of Fluids (2025). The article can be accessed at https://doi.org/10.1063/5.0288043 .