Stable hovering of a jellyfish-like flying machine

TLDR

Flapping‑wing aircraft (ornithopters) offer a small‑scale alternative to helicopters, but achieving stable flight remains a key challenge. The authors present a self‑righting hovering machine that relies solely on flapping wings, without extra aerodynamic surfaces or feedback control. They designed, built, and flight‑tested a prototype with four jellyfish‑like wings that open and close, using high‑speed video and motion tracking to confirm stable body orientation, and developed an aerodynamic model linking centre‑of‑mass location to coupled translation and rotation. Lift measurements demonstrate that wing flexing and appropriate wing size improve performance, and the results suggest that flapping‑flight strategies can succeed beyond animal‑mimicking wing motions.

Abstract

Ornithopters, or flapping-wing aircraft, offer an alternative to helicopters in achieving manoeuvrability at small scales, although stabilizing such aerial vehicles remains a key challenge. Here, we present a hovering machine that achieves self-righting flight using flapping wings alone, without relying on additional aerodynamic surfaces and without feedback control. We design, construct and test-fly a prototype that opens and closes four wings, resembling the motions of swimming jellyfish more so than any insect or bird. Measurements of lift show the benefits of wing flexing and the importance of selecting a wing size appropriate to the motor. Furthermore, we use high-speed video and motion tracking to show that the body orientation is stable during ascending, forward and hovering flight modes. Our experimental measurements are used to inform an aerodynamic model of stability that reveals the importance of centre-of-mass location and the coupling of body translation and rotation. These results show the promise of flapping-flight strategies beyond those that directly mimic the wing motions of flying animals.