The basis of Volerian’s propulsion system is an oscillating wing set into a specially shaped duct. A stator wing is located downstream to further increase efficiency.
The flapping action of the wing creates a stream of thrust producing vortices known as a reverse Kármán vortex street.
The ducted wings are built up into an array that provides the area needed for thrust and control. The array has a high ratio of lifting surface to thrust area which reduces the energy in a given length of wing thereby increasing safety and reducing the engineering requirements and noise. In theory any wing length can be used, with the help of additional bearings.
An array can be adapted for different flight requirements, for example a very quiet, large thrust area with good short range qualities or a smaller thrust area for faster, longer range with the ability to take-off conventionally.
The simple 2-dimensional geometry of the main aerodynamic shapes allows them to be produced in composite materials using pultrusion manufacturing methods. This will greatly reduce the cost of manufacturing the aircraft.
The wing motion is typically controlled by a cam connected to three wings to keep the motor loading constant. Aircraft using a large array can simply change motor speed for control.
An array aligned with the direction of flight allows air to flow through the ducts. This avoids the problems of flow separation that occur with conventional ducted fans. All moving parts are still safely located within the ducts. In the event of an unpowered descent the fluttering action of the wings, caused by air flowing up through the ducts, will create drag and cause the array to act like a parachute.
The pressure changes along the length of the wing are constant (unlike a propeller blade which changes as the angular velocity increases towards the blade tip), so there are less 3-dimensional effects at the wing tips and the energy is more spread out which is beneficial for noise and efficiency. End plates, as shown in the above cutaway, can be used to further reduce the effect of wing tip vortices.
Turning vanes help adapt the array for faster, more efficient cruise and for control purposes. In this case they also turn the airflow away from the cabin which helps reduce cabin noise.
The spars that connect the array also act as wings to take part of the load during flight.
This cutaway shows the batteries in a streamlined case above the array which helps with the centre of gravity and has greater safety in case of thermal runaway. Simple support structures hold the cabin, seat and undercarriage in place.
Faster, more efficient cruise can be achieved using a deflected thrust system. This gives the aircraft excellent short take-off and landing capabilities as well as VTOL. Flaps are all fully immersed in the jet which prevents stall, enabling a very high lift coefficient and avoiding control problems arising from detached flow. Aircraft using this system can take full advantage of the high propulsive efficiency of flapping wings.
The geometry was optimised using computer models. This video shows the pressure changes caused by the flapping wing and the interaction of the vortices with the stator wing and duct walls.