Have you ever seen one of those Dyson bladeless fans, and wondered how the heck they worked? How is air moved without any fan blades? It’s pretty cool technology, but you may be surprised to learn that the science behind it is over 100 years old. The Coandă effect was discovered in 1910 by Henri Coandă, an inventor from Romania who was building an airplane at the time, ostensibly propelled by air drawn through a fan shroud. He noticed that the stream of air produced by his unusual engine design closely followed any nearby surface. In his own words, the Coandă effect is “the tendency of a jet of fluid emerging from an orifice to follow an adjacent flat or [convex] surface and to entrain fluid from the surroundings so that a region of lower pressure develops.”
The diagram above could be a cross section of a Dyson bladeless fan or the fluidic propulsion system of an aircraft: the Coandă principle is the same. An impellar or compressor [black] at the bottom of the image forces air into the ring of the fan where it exits through a slit near the front of the ring. The forced air follows the flat surface which is wider at the back than the front, creating a low pressure area. Air from in front of the ring is at a higher pressure, so it rushes into the ring. Thus, air flow for the Dyson fan (or thrust for an aircraft) is created.
A startup called Jetoptera in Edmonds, Washington, has designed a flying machine utilizing the Coandă effect, which they call the Fluidic Propulsion System (FPS™). FPS™ provides the thrust for Jetoptera’s J2000 VTOL (Vertical Takeoff Or Landing) aircraft. The motor driving the impellar/compressor could be powered by fossil fuels or electricity. Jetoptera’s initial designs will use a gas turbine engine, which could be replaced later by an electric motor once battery energy density improves to offer a better power to weight ratio.
Notice that the FPS ducts are rectangular with rounded corners: nothing says they have to be round like Dyson’s bladeless fans. Jetoptera’s radical and innovative design goes far beyond the Fluidic Propulsion System. The wings and airframe are unique as well. Two stacked wings reminiscent of a biplane are located in the back and boxed in with vertical stabilizers. This wing arrangement allows for a narrower wingspan and therefore a more compact design while still generating plenty of lift. The main FPS ducts are mounted within the boxed wings. While the J2000 is designed for a maximum speed of 200 mph (and that doesn’t sound like alot), remember it’s designed for economy, efficiency, and vertical takeoff and landing, qualities that most aircraft in use today can’t compete against.
This isn’t the only technology people are working on to advance flying without propellers or jets, but it’s one of the most interesting. BTW, Jetoptera is also developing drones and military aircraft based on their FPS VTOL concepts.
“Jetoptera’s Bladeless Propulsion System” (10:28)