Powered spinning propellers were never present in nature and when nature wanted to produce thurst in a fluid, it did so by flapping things back and forth. The VTOL aircraft propulsion system also aims to do the same with a series of flapping wings mounted in large ducts, Ignoring the energy density issues which are holding back the electric aviation industry. Multirotors are very noisy and also have no proper safety systems in place if the power system fails. A startup called Volerian claims to have found a solution for both these problems. The startup is using a unique propulsion system which was never tested before.
The system places a large number of flapping wings inside a series of precisely shaped ducts. The wings are operated by cams on a rotating shaft so that they wave back and forth quickly between the walls of these ducts, just like the tails of fish. Another fixed stator wing is mounted further down the ducts ‘to further increase efficiency’ by messing with the swirling pressure which is created by the flapping wings. The company claims that its flappers make less noise than a similar multirotor system and it is a safer system as well. In the event of power loss, the wings can be released to flutter against the airstream which is coming up through the bottom of the vents when the aircraft falls. There are also no rotating decapitators in the system which can cause worry as per safety point of view.
Volerian is proposing a range of different aircraft based on the odd propulsion system. If you point them forward, you can build a conventional winged airplane. This gives you a VTOL craft ready to be used as a flying taxi, although it is not clear how horizontal thrust control will be achieved in such cases. The company has so far shown few renders and a single-wing demonstration rig which it rolled out this year at the Farnborough airshow. This rig was running at a low speed, but it demonstrated that these wings are so less noisy that they are almost silent.
Volerian is planning a modular factory design which can be rolled out to multiple production partners. The systems seem to be dependent on various moving parts which can be damaged easily by a bird strike or a similar accident. The thurst the system provides also relies entirely on the flapping speed. There are many questions regarding the functioning and design of the system which need to be addressed before the design is finally implemented.