Determine whether synchronized vortex merging generalizes across flight conditions and configurations

Determine whether the globally synchronized vortex-merging phenomenon observed in the hovering full-scale quadcopter wake occurs across different flight conditions and quadcopter configurations.

Background

The paper identifies a globally synchronized, non-subharmonic vortex-merging process involving all four rotor wakes. This process appears at an incommensurate frequency below the rotor-frequency band and is interpreted as arising from mutual coupling among the individual wakes.

Although the phenomenon is robustly characterized in the reported experiment despite rotor-speed variations, vehicle drift, finite resolution, and measurement uncertainty, its occurrence beyond the specific hovering configuration and operating conditions studied remains unresolved. Establishing its generality would determine whether synchronized vortex merging is a broadly recurring feature of multirotor wakes or a condition-specific phenomenon.