A Whole New Mode of Aircraft Propulsion?

Jetoptera demonstrates model with remarkable new engine.

It’s not so much an emerging aircraft as an emerging family of aircraft or, if the technology pans out at larger scale, a new paradigm for propulsion. Jetoptera (yeah, we’re still figuring out how to pronounce it, too) has been developing this concept for a while now, and its latest scale model, without question, puts on an impressive performance using the new propulsion system.

Qualifications and questions to follow, but the idea as best we understand it is that the system uses a power source—designers are bullish on gas generators—to provide straight thrust that is then ducted around the craft to wherever the aircraft designers want it to go. In theory, and in Jetoptera’s concept drawings, that thrust could go into oval tube thrusters that could be vectored. Vectoring the thrust or just tilting the thrusters could be used for VTOL operations. With the footprint of the thrusters, designers would, again theoretically, be able to place them anywhere on the aircraft. Some of the company’s drawings show them deployed toward the wingtips. The model, however, is a twin with the engines near the centerline of thrust.

On its technology, the company is somewhat broad in its descriptions: “The complete propulsion system,” it writes, “is a unique combination of a gas turbine and fluidic thrust augmentation that can distribute thrust across our airframe.” We think that means that it ducts thrust anywhere. Just what “thrust augmentation” is, we don’t know, and the company doesn’t go into much detail on it. The descriptions continue, explaining that the thrusters (our word), “…can be implemented in various geometric shapes, can be embedded with the airframe, and has no propellers or rotating parts. The system is used in all phases of flight.” Jetoptera does indeed show a number of concept configurations, some of which are intriguing.

On the subject of power source, while Jetoptera says that it is energy agnostic, it strongly qualifies that statement, writing, “The energy required to propel our smallest aircraft at 200 mph for 30 minutes is 100 kWh. This energy can be provided by 26 kg of jet fuel or 600 kg of modern Li-ion batteries. Should battery technology evolve to better than 1,500 Wh/kg, we can use it in our designs.” This goal is nowhere near being in sight for electric storage developers. Our view? It’s refreshing to see the company being straight about electric propulsion’s limitations.

The model in the video looks to us a lot like the Lockheed U-2 spy plane, with a high-aspect ratio wing and propulsion mounted near the centerline. The figures quoted for top speeds are all over the map, from “nearly 200 mph” to Mach .80, which we presume covers a range of different implementations of the technology.

We’ll keep a close eye on the company’s progress with its designs and look forward to seeing a full-scale example taking to the skies.