Researchers at MIT have done some tinkering and may have revolutionized propeller design. Almost on a scientific whim, a team at the Lincoln Laboratory whipped up a few batches of “toroidal” propellers for a drone on a 3D printer and discovered they were not only much quieter than the OEM props but they put out more thrust at the same power level. The new props were a side project to their real job creating an entirely new form of silent aircraft propulsion using an ion drive.
The result is a closed loop design that looks like a couple of opposed inclined boomerangs joined at the tips. Researcher Dr. Tom Sebastian told New Atlas the prop design was inspired by some obscure “ring wing” aircraft prototyped in the early 20th century. He’s not even sure why they work but theorized their odd shape greatly reduces the noise-creating vortices that come off the tips of regular props.
“The key thing that we thought was making the propellers quieter, was the fact that you’re now distributing the vortices that are being generated by the propeller across the whole shape of it, instead of just at the tip,” Sebastian said in a video. “Which then makes it effectively dissipate faster in the atmosphere. That vortex doesn’t propagate as far, so you’re less likely to hear it.”
He said they haven’t spent much time optimizing the design but it shows promise, particularly for eVTOLs and drones. It also works remarkably well for marine propulsion, and there are already commercially available toroidal boat props on the market that boost power, flatten out the acceleration pitch of boats and markedly reduce noise.
As for Sebastian’s real job, the Lincoln Lab has already flown a small model plane that generates an “ionic wind” for propulsion. The plane has no moving parts and doesn’t use fossil fuels. “This has potentially opened new and unexplored possibilities for aircraft which are quieter, mechanically simpler, and do not emit combustion emissions,” spokesman Steven Barrett said. Again, drones will likely be the first application for the new power source but Barrett foresees hybrid designs that could create more fuel-efficient airliners and cargo planes.
That is pretty exciting. The video of the boat with and without these propellers doesn’t seem believable it is so much quieter. Pretty amazing.
Dramatic indeed. I assumed nearly all the sound in the standard prop was from the engine itself. It would be really interesting to make one for a regular aircraft.
If they would like to 3d print me one for about 80hp at 42″ diameter – I’d be happy to EXPERIMENTal with it for them.
The propeller innovation is exciting but the last paragraph just makes me roll my eyes.
Almost all the energy we use is derived from fossil fuels. Even wind and solar require massive machines that take massive amounts of energy to manufacture and have limited life. People that think electricity is clean and free are just adorable. There is just no such thing as a free lunch.
The lack of moving parts is interesting but the ion airplane article makes no mention of the amount of electric power required to sustain thrust. It is not zero. Exporting your pollution to the power plant doesn’t earn you a halo.
As an aerospace engineer working in the field, I can say that anyone who encourages you to think we believe there is a free lunch is incorrect.
This is racist and should be flagged!
Not racist, just classless, crude and says more about the poster then it does about electric propulsion or Stacey Abrams. Basically adds nothing to the conversation. Well done.
And as far as the costs associated with electric vehicles and wind and solar generation… Dennis B. is right. There are costs. Innovation is difficult, expensive and risky. That’s not news. Doing nothing on the other hand, is defeatist and cynical. That attitude would never have led to the first flight in an airplane and I’m always surprised and disappointed to hear pilots (of all people) mock and deride innovation, risk taking and experimentation. This is a “yes, and” situation. Fossil fuels will continue to be a critical piece of energy puzzle for many years. Knowing that does not, in any way, discourage me from celebrating every exciting new development in electric propulsion and generation.
Sounds like the “distributed vortex” prop will prove to be a solid advance for the vertical lift drone crowd.
Ion propulsion? Maybe in a specialized ultra-quiet sailplane-like recon drone, but for lift-by-direct thrust? Not so promising.
As a former Anti-Submarine Warfare (ASW) specialist, it would seem to me that this technology could be huge, if it can be scaled up to work on submarines. The name of the game in ASW is silence. This could really make a difference–J props and scimitar blades help, but this could be a game changer.