Conceptual design and aerodynamic analysis of a Mars octocopter for sample collection

Mars sampling is of great significance for the comprehensive study of Martian geological evolution. The successful demonstration of the Ingenuity Helicopter reveals the potential of rotorcraft for sampling tasks on Mars. However, the Ingenuity Helicopter cannot carry samplers, and large helicopters face difficulties in folding automatically. Thus, a multi-axis rotorcraft may be more suitable for Mars sampling tasks. This paper proposes an octocopter named MarsBird-V with a foldable rotor system and wheels for moving agilely. The design method for the structure and control system of MarsBird-V is illustrated, followed by the mass and power estimation approach. On the basis of the blade element momentum theory, the criterion is proposed for the aerodynamic performance evaluation of the coaxial rotors. The aerodynamic data of the coaxial rotors are obtained by the computational fluid dynamics method, which is applied to determine parameters. The propulsion capacity is calculated in the rotational speed range limited by the Mach number of the blade tip. As estimated, the minimum gross mass of the MarsBird-V is 6 kg. The proportion of payload in the gross mass increases as the power increases. The MarsBird-V achieves maximum durability of 420 s at a power of 1017 W and obtains a maximum payload efficiency of 0.43 g/W at a power of 2362 W. This paper also presents the deployment process and mission analysis. The MarsBird-V can perform sampling tasks in a cycle time of 2 to 5 days.