  Attempts to use Electrohydrodynamic (EHD) flow for propulsion have been made
since the last century [1]. Limited success has been registered particularly
due to the inhomogeneous generation of the thrust, and also the very light
weight and frail nature of the devices versus the power supply weight needed
hover the craft [2]. However, EHD propulsion can offer a greater thrust to
power ratio than any of the current propulsion technologies [3]. Rotary EHD
devices have been employed as demo units for a long time [4,5], but it was
unknown if they could produce enough thrust and vertical lift to lead to device
liftoff. We designed EHD propellers which spin and eventually lift off and fly
independently for a short while. The propeller is balanced on and powered
through a high voltage pin/shaft while an intense electric field is created by
the presence of a surrounding ground electrode [6]. Multiple propeller
electrode designs and ground counter electrodes are able to support propeller
rotation and liftoff. Propellers up to 27.8 g and 25.5 cm in diameter were
studied with a liftoff voltage range of negative 9.5 kV to 60 kV and rotational
speeds up to 80 rot/s. It appears that these are the first EHD devices to
liftoff and fly on their own without carrying a power supply [7]. This
validates a rotary-based system as a new principle for propulsion with
potentially improved stability and control characteristics versus the current
EHD devices. Design optimization and scaling seem possible and EHD drone design
feasible. Other applications may include EHD motors, fans, or sensors.
