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In traditional aircraft design, airframes and engines are designed separately and bolted together. This leads to inefficiencies due to additional drag. The approach also leads to propulsive inefficiencies via non-distributed propulsion. Hovering and VTOL requirements introduce even more complexity, size and weight to the system.
Jetoptera’s design is a true distributed propulsion that is integrated into a novel airframe. It improves propulsive efficiency by more than 10% while lowering fuel consumption by more than 50% compared to small turbojets. The propulsion system saves approximately 30% in weight compared to turbofans or turboprops and also significantly reduces complexity. The integrated aircraft is capable of hovering and VTOL.
The props on today’s aircraft are inefficient, noisy & dangerous — but an innovative new bladeless propulsion system by aerospace startup using a revolutionary technology called the Fluidic Propulsive System™ – offers an alternative for 21st century aviation. Helicopters are big, with a large footprint. The spinning rotor is large, and makes it somewhat dangerous to get close to things. They can’t easily glide, and they’re noisy, expensive, and hard to fly — there are lots of problems with helicopters that have held them back, and we wanted a better alternative.
“If you look at the history of aviation, the big changes always start with a propulsion system. That’s really what enables everything, so we started Jetoptera with the idea that we’d create a new propulsion system that would be ideal for VTOL and enable powerful drones and eventually flying cars, said Dr. Denis Dancanet, the CEO of Jetoptera. We decided on the name because “ptera” means wing in Greek, so Jetoptera literally means “jet wing”.
A scientist named Henri Coanda — who coincidentally happens to have been Romanian — and was working in Paris about a hundred years ago. He noticed that if you have a jet of high speed fluid going along a convex surface, it’s tends to stick to that surface and additionally entrain ambient fluids. Jetoptera propulsion is based on Bladeless fans, that introduce a flow of fast moving air on the edges and that creates a drop in air pressure within trans-ambient air. They produce enough air movement to heat or cool yourself, but not enough to produce real thrust.
“The question for us was how to design these Coanda effect “thrusters” so that they not only produce a usable amount of thrust, but more importantly continue producing augmented thrust as you’re moving forward through the air. We also wanted the same system to be used both for the vertical lift and forward propulsion — which saves on weight and complication. Our design lets you easily rotate the thrusters, there’s nothing moving inside them except air, and they’re very compact, says Dancanet”
Another part of our design enhances thrust augmentation, which happens by entraining ambient air & accelerating it through the thrusters. Our thrust augmentation numbers already proven in flight are more than two to one, which has never been achieved before. Another area of achievement for us is designing and airframe that works in conjunction with the propulsion system. Typically, aircraft manufacturers buy an existing engine and bolt it onto their airframe, which is inefficient. We wanted to do better, so we designed an airframe that entrains ambient air, and directs it over lift-generating surface surfaces, for lift augmentation.
All of these things work together synergistically, which is why our airframe shape is so unique — we have a box wing design with thrusters inside and a canard in the front with thrusters behind it. So the combination of thrust augmentation & lift augmentation gives rise to pretty unique looking aircraft that’s extremely compact, can do VTOL, has a smaller footprint than a helicopter, and flies a lot faste.
The performance is in an unprecedented sweet spot between a helicopter & aircraft. We’re not claiming it’s the best at everything — it’s actually more of a novel design with new abilities. For instance, it’s faster than a helicopter, with a top speed around 200 miles an hour if the thrusters are in the open. We do have a design where you can fold the thrusters into the back of the wing, which keeps them out of the slipstream, and enables speeds up to 400 plus miles an hour.
A helicopter is going to be more efficient at hovering for long time periods because it’s hard to beat the efficiency of a large propeller. But if you want to be able to do both VTOL and then go very fast somewhere, we are going to be better. Also, keep in mind the large rotor in a helicopter is very noisy — and it’s not just the sound level that people find annoying, it’s the percussive nature of the sound.
Our system makes a lot less noise, and part of the reason is that the noise of such a propulsion system is proportional to the eighth power of the speed of the exhaust. So if you reduce the exhaust speed dramatically, you will even more dramatically reduce the noise. Turbo jet exhaust comes out at 1,500 miles an hour, which is ear-splitting even at a large distance. In our case, mixing in the ambient air takes the net exhaust speed down to 300 miles an hour, which provides a significant reduction. Right next to our aircraft we’ve measured a hundred decibels, and at 400 feet, it would be about 70 decibels, compared to a small helicopter at around 85 decibels.
Larger propellers are more efficient, but they’re also noisier & more unwieldy — but when you scale them down, they become less efficient. When you go down to ducted fan level, those have to spin at extremely high RPM, which makes them noisy and prone to blade-out events that make them more dangerous, sometimes deadly. That’s why companies like GE spend significant amounts of time and money testing their engines for blade-out events.
Jetoptera technology, can be scaled down to enable VTOL for aircraft around 100 pound total weight and scale up to 6,000 pounds and beyond, which gives us a pretty wide range of uses in both autonomous & manned applications. Such propulsion system could have roles in emergency services, logistics, mapping, military, and even commuter applications.
Another safety aspect of our design is the fact that our airframe has a glide ratio of seven to one, which is a major advantage over a helicopter. We’ve also looked at the idea of attaching a ballistic parachute, like Cirrus aircraft — which has a great feature that’s helped save a lot of lives.
Another strength for us is the gas-turbine we’re using to produce compressed air. At some point when battery technology catches up we can go electric, but what we’re using right now is extremely well understood, and been in aviation for a long, long time. That gives us proven predictability & reliability in our powerplant that electric vehicles don’t yet have.
They expect first applications will be with the military because they have existing programs & needs to address, and they’re outside of the FAA jurisdiction. “That’s not to say they don’t care about safety. Of course they do, but military applications have an easier initial threshold, and after we’ve accumulated flight hours there we can use that to demonstrate to civilian authorities that everything is fine.”
In terms of partners, we currently have a partnership with GE Aviation, and just announced one with Honeywell, both intended to provide us with a source of compressed air. We’re working toward partnerships on the airframe side as well.
The largest vehicle we’ve built so far is a quarter-scale model of the J-2000, which is a 2,000 pound aircraft carrying two passengers. We’ve built & flown it — again, at 1/4 scale. In another year’s time, we should have a 1,000 pound aircraft, and in the next two years we’re looking at a full-scale prototype of the two passenger aircraft. These are all prototypes, though — they are not yet certified, which takes time.
Army SBIR test results indicate the FPS is the most silent propulsion method in the skies
Jetoptera has conducted a series of tests to measure the noise signature of its patented 200 lbf-class Fluidic Propulsive System (FPS™) thrust augmentors as a subcontractor to Paragrine Systems, under a United States Department of Defense-funded research collaboration. The testing compared the Jetoptera FPS™ to a conventional reciprocating engine-driven propeller propulsion system and found an up to 15 dBA lower Overall Sound Pressure Level (OASPL) output based on equivalent power and before application of any additional noise mitigation technologies. Acoustic treatment will increase its advantage to more than 25 dBA OASPL over a rotor on a similar power basis.
The tests were conducted as part of Paragrine’s development of advanced parafoil platforms with highly efficient, low-noise propulsion as an important objective. Jetoptera has been selected for the program because of FPS’s maturity and unique potential for integration into innovative propulsion system configurations. This round of testing evaluated an FPS geometry whose aerodynamic performance Jetoptera has previously demonstrated on a 7-meter wingspan unmanned aircraft used as flight test bed, in multiple VTOL and hovering flight tests, and in the University of Washington wind tunnel.
Optinav, Inc., conducted the acoustic evaluation by using its BeamformX Acoustic Array System, which is a sophisticated instrument that precisely and accurately measures emitted sound profiles and pinpoints the precise sources of audible vibration for actionable solutions. The data analysis was performed by Dr. Robert Dougherty, whose scientific contributions were recently recognized by the AIAA with the Aeroacoustics 2020 Award.
In addition to testing the FPS, the same setup and procedure was applied to a 11-kW internal combustion engine-driven 1.25-meter diameter propeller turning at maximum RPM with a resulting blade tip speed of Mach 0.46. Broadband and narrowband noise measurements were performed with directivity resolution. The test results show up to 15 dBA lower noise performance of the FPS™ versus the propeller, before any FPS™ noise abatement, based on equivalent power level. With the data collected and considering the directivity and atmospheric absorption normal day, we can now predict that at 300 meters the FPS™ would produce less than 50 dBA even before abatement hence, significantly lower than the 65 dBA goal of UAM communities. The FPS will be the most silent propulsor in the skies.
“Unlike a propeller, the FPS™ can take non-round shapes for perfect integration with the wing and therefore is more amenable to further noise abatement via passive and active acoustic abatement techniques. The team applied a technique of placing the thrusters inside various enclosures which further reduced noise emissions by another up to 5 dB, at a modest cost to the thrust performance,” said Dr. Andrei Evulet, CEO of Jetoptera.
“This is a very significant lower noise emission level compared to any propeller system, on a same thrust rating comparison, as the inevitable tonal noise from the propeller or rotor dominates the acoustics of such a legacy system, be it electric, piston or turbine driven,” he continued. “We have just demonstrated how our propulsion method will be quieter by a significant margin, even before we incorporate abatement methods. We also compared the aeroacoustic data collected to the noise signature of some advanced propellers that have been developed and reported in the past five decades by NASA and others and the FPS™ was found to have the potential to be up to 20 dB lower and having no tones, an advantage that cannot be matched by any rotor or propeller. Our next steps include the use of the FPS™ in conjunction with an Upper Surface Blown (USB) Wing, which will further reduce the noise levels, as NASA studies have confirmed over several decades of research.”
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