Maple-seed-inspired rotochute

The maple seed has a winged structure that autorotates during descent, thus generating leading-edge vortices, providing enhanced lift and reducing descent velocity. Inspired by this flight principle, we developed a minimalist rotochute that is comprised of a wing, a payload, and a counterweight. At the laboratory scale, the maple seed-inspired (MSI) rotochute exhibited excellent descent performance, achieving a descent velocity as low as 0.94 m/s and a rotation velocity as low as 71.47 rad/s. The ratio of its descending velocity to mass demonstrated that the MSI rotochute had better efficacy than the natural maple seed. By integrating the blade element theory and Eulerian equations, a theory of the MSI rotochute in steady descent and rotation was proposed to quantify its flight behavior. Both the descent and rotation velocities increase as the payload–counterweight mass ratio or the leading edge–counterweight mass ratio is increased. When the payload moves away from the center of mass in the spanwise direction, the descent velocity decreases slightly, but the rotation velocity increases slightly. To validate these theoretical results, experimental measurements in a custom-designed wind tunnel were performed and good agreement with theoretical predictions observed. This study provides guidelines for designing novel MSI rotochutes for a range of applications, such as airdropping, emergency escape from tall buildings, and recovery of unmanned aerial vehicles.