Toroidal Prop Testing: Is this the future of FPV propellers?!
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- Опубликовано: 30 июл 2024
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Timestamps:
0:00 Intro
1:33 How do they work?
3:52 Manufacturing test samples is HARD
5:18 Toroidal props sound different (maybe better?)
6:57 Sound pressure level measurements
7:46 Check out the data
8:18 Thrust measurements
9:12 Efficiency measurements
10:35 Weight and moment of inertia
11:47 Conclusions
13:40 Brilliant! (.org)
14:43 Outro
Video sponsored by Brilliant. 
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Those scientists at MIT didn't come up with anything, they just added the wrong name to the mobius strip propeller so no one would find other research. I found a publication dated 1996 on the subject of these propellers. You can find them by searching"Propellers And Fans Based On The Moebius Strip" or "Screws, propellers and fans based on the Moebius strip"
A regular 5 blade propeller is much quieter than a 3 blade propeller. Noise reduction and greater thrust also improve with more blades, but the load on the motor increases. This seems to explain the effect of these propellers. It's just a different design doubling the number of blades, with more extra mass at the ends. On motors with a power reserve, thrust will increase, due to increased consumption and the efficiency of grams per watt will noticeably decrease
This is just yet another empty hype crap to collect sponsorship money
@@hesher. or a very cool trick to annoy people with their stupid and cheap video so the public would actually try and prove them wrong and develop this for them?
@@hesher. They may have copied the idea from the mobius strip boat propellers, but these propellers do have the potential to be far better than conventional ones. They just need to be perfected first. Look at how much more efficient Sharrow boat propellers are than normal boat propellers.
Thanks for summing it up. I was about to write something similar.
6 blade props are more quiet indeed. Also like you said because of motor load, you cant just replace a 3 blade with a 6 blade or toroidal in the same size/diameter, without overloading the motors. You need to go down like an inch.
@@Chris-hn4lp It is very likely we will not see the same benefits as the Sharrow propellers. Moving through water is much different than moving through air.
Specifically the Sharrow propellers prevent water cavitation from forming at the blade tips which drastically reduces propeller efficiency.
I'm not an expert but from my understanding there is not a direct equivalent of cavitation for propellers moving through air.
It might have been a good test to 3D print the Nazgûl prop so you could see a quantifiable amount of degradation due to printing. You could then somewhat speculate how much more efficient the toroidal props will be once they’re injection molded.
I have to say, with all the tests already out there, I’m not sure why Chris missed this detail. It gives it more of a even playing field to test the new tech.
The drag might equalise them both though. I think something better is to use body filler on the props and sand them smooth and balance them after
@@Athiril Or use the acetone-vapour smoothing method.
Ah, just got to the part where he adress this point
Would a resin 3d printer be better?
I'm actually quite surprised that my V3 tri-loop managed to perform as well as it did considering how old it is now. Wish I had more time to explore the topic more, but thank you for doing this really solid testing. I casually theorised a lot on the possibilities and potential of toroidal designs, and your very thorough testing I think has brought us to very similar conclusions. I was never of the thought that toroidals would ever replace standard designs, since an aim for efficiency and more discreet operation is a bit of a clash with acrobatic flying, but I still think maybe the Cinewhoop space could benefit in some ways. Certainly the tri-loop looks less likely to cut us up 😅.
If it's not too much to ask, I'd appreciate a tag - also helps me keep track of people who've tested my design as I've been maintaining a playlist on that as well. You might find that interesting, especially one of the videos by MoppelMat where he printed the V3 tri-loop out of Nylon-CF and made props lighter weight than equivalent 5" injection-moulded props he had lying around:
ruclips.net/p/PLYXuRA_sySbwa7FRot80kzEA_j4iqWQ_w
Also, Foxeer just posted a teaser on their Facebook of a production injection-moulded bi-loop design which would be worth putting through its paces, I think. Proves that injection moulded the bi-loop is possible, now wondering if they might be able to work-out injection moulding the tri-loop. Exciting times, hehe.
I can't find that foxeer post on facebook. Can you confirm it's still there? Any date?
Still waiting for foxeer to release.
@@chrisbee5481 Yeah it's delayed for some reason. I asked and they just said "soon", so I'm wondering what's up. Could be manufacturing, maybe. Or if they've sent out review samples maybe they want a bunch of influencers to post about it at the same time as release? I dunno, completely guessing 😅
You should test this 'three' blade moebius strip propellers with 6 blades regular propeller, because this design just doubles number of blades
This is important, because the 6 and even 8 blade props are substantially more quiet than even these toroidal props. Quadmovr had a great video showing this when MIT first put out their press release.
Indeed. HQProp offers 8-Blade Props (in 2.5", 3" and 3.5" I think). They are indeed quieter and also have a similar windy sound.
I think the material of the prop is also really important. You can see printed props bend significantly when they spin. This can reduce their performance. I wonder how would they perform when made of polycarbonate.
Yeah, the deformation of the prop while spinning was quite evident, especially on the last one (strinkingfpv 3 loop) @6:00. The area inside each loop seems to be expanding (i.e. what would be the "tips" seems to be pulled towards the center as the "wings" of the loop are spread apart).
Polycarbonate can be printed on (generally only advanced) 3D-Printers, but it isn't trivial. They require exceedingly high temperatures for the hotend (~300°C) and relatively high for the bed (100+ °C). Even then, it remains to be seen if they behave differently due to their layer-based construction compared to injection molding, as stresses from high RPM might manifest differently despite them being the same material.
Another way would be to print negative molds and construct them from CF+Epoxy or similar, but that again is a very different and extensive process.
They could be cut out of a solid block with a multi axes laser cutter, perhaps.
@@putteslaintxtbks5166 nope, but with a 5 axis mill it can be done
negative, bad layer adhesion on PC, needs rebakiing, that warps a bit the shape, all goes bannanas, best is CF Nylon, or CF PPS for cheap money, for bigger money PEI or PEKK CF.
Just an FYI all the props he tested were made by non aerospace engineers who just made something that looked right. You honestly can't expect someone with no background in such a complicated field to make something better than what we currently have. Now seeing a toroidal prop made by someone with the proper engineering background would be quite interesting. However, even seeing that these props can bet a bit close to our current props shows that it will likely end up being something worth using.
This is what I've been thinking since this whole toroidal prop craze started.
@@thirtythreeeyes8624 not to mention 2 dB is almost twice as quiet, not much of a difference my a**, it's a freaking logarithmic scale
I think to do an apples to apples comparison, you should CAD up the traditional blade and print it on an SLA printer (as close to the same process and finish) and see how much the performance diminishes and compare that. If you see more than a 10% drop in efficiency on either thrust, power or both, there's definitely something here. Best!
Great video! A couple notes: It would be very interesting to see the noise power over frequency. Also SLA still has tiny layers which still could or could not impact efficiency and noise.
Chris - thanks for putting the drawing files with details on the AOS page - loving my 3.5" AOS O3 Freestyle!!
I'm just finding this now. It was neat seeing some of my designs get tested and that they worked as well as they did. When I was designing these I was just learning cad and used these as a challenge to improve my skills. I didn't use any special airfoils or anything. Just eyeballing these and slowly improving them. At the time I didn't even have a 3d printer so I had to rely on others to print and test them for feedback. Most of my designs were designed for easy FDM 3d printing so the bottom of the blades were flat to adhere to the print bed. I've since learned a lot more about prop design so it'd be neat to do some new designs meant for SLA printing.
Thank you, that was a great review of a new technology in props, with very interesting results.
Great information. Thank you Chris for this video!
As a prior AV Production Technician, thank you so much for using the 1 meter standard for measuring noise! So many you-tubers just hand hold their meter so close that the results can easily be skewed but an inch or two of distance.
Compare the StrikingFPV triloop to a 6 blade prop.
Great video. I really liked it. Keep up the good work.
I’ve been expecting to hear a fluid dynamics interpretation of this MIT toroidal prop stuff from you so this video is most welcome. Sounds like that cold has taken a toll on your voice, I hope you’re on the back end of it now though, get well soon Chris. 🤕 Great video, thank you.😊
Interesting data. What happens if the airflow is not perpendicular?
Thanks for cutting through the hype, Chris. It's interesting to have seen GemFan's comment on JB's livestream the other day. The message was something along the lines of them wanting to move forward, but not necessarily knowing how to work out the credit / attribution to the MIT team. The fact that there is very little technical information available from that team, and that folks have to reverse engineer the dimensions and parameters is frustrating, to say the least.
Foxeer will be selling toroidal props later next week. I'm guessing they just bypassed MIT entirely to get them made.
Great video! Thanks for the great information. I think, toroidal props vs cinewhoop test will be a great test.
Thanks Chris!
Sweet video, great information!
Curious given your explanation of how the noise is altered, why wouldn't a tradition bi-blade with down-turned blade tips work much the same way without the weight problem? I am also thinking that toroidal props with tend to bend into a unbalanced state to easily after crashes.
At the tip of the toroidal blade, what would happen if holes were drilled to let the air escape the cupping of the air? Would this allow the blade to speed up with less resistance?
Really excellent examination of the propellers for the key properties of interest! Perhaps I missed it, but was there a comparison of the noise level for the same thrust/power, or was it only at the same speed? I imagine it would be more important to consider the noise level vs. the amount of thrust you can achieve ultimately if you are optimizing for that. I guess a frequency analysis of the sounds could also help in determining why they seem quieter/less annoying.
Thanks Chris.
It is worth noting that a 3 dB decrease is half as loud, so in theory the three blade Willow toroidal prop is half as loud as the two blade Willow. When you were testing the props did you notice a significant difference in volume or was the perceived difference less due to the different sound profiles?
it should be a significant difference in volume, saying 2-3 dB different "isn't much" is completely ignoring that it's a logarithmic scale, I don't know if he's oblivious to that or just being facetious
Were sound measurements done at a fixed thrust value for all props? That is, is a toroidal prop any quieter when it needs to produce same thrust as a normal prop?
I am curious of performance and durability. Are they going to be louder when damaged? Are they going to still be mostly functioning at close to normal performance when damaged? Are they going to be flyable when damaged?
Durability is a good point. But i think those would be more for Longrange + Autopilot applications than for freestyle
I have tried a number of different toroidal props with a 3" quad, but have a lot of oscillation issues that I can't over come. Which I think is due to the props larger mass, the little 1404 motors just couldn't accelerate the toroidal props as needed. Could there be size limits?
It's more likely to be a balancing issue with the printing rather than the design itself
There was a testing of Toroidal propellers on out boards for 25 ft boats there abouts. The area where the Toroidal propellers excelled over conventional 3 blade propellers in terms of speed, fuel efficiency, noise was between a 3000- 4500 RPM range.
Chris, get better soon! Thanks for great video! Did you one Zipline propeller design with 2 blades on a side being counterbalance with droplet-style weight on another. It seems ever more quiet. Can you test that shape for FPV as well?
It makes sense that the thrust from the cordial props would be less efficient because there is more surface area, therefore more drag.
Thank you, this is very good information. I would love to see an audio spectrogram or FFT for the sound produced by the toroidal vs traditional props. Also, I agree that the efficiency of these new designs will improve fairly quickly.
Could you please share the 3d file link of willow propeller? Thanks!
Thanks for posting this...fascinating. One thing I think would help you understand your perception of the dB SPL measurements. You are on the right track...but Human ears are more sensitive to 1k Hz and higher frequencies. In audiology we measure in dB HL (hearing level) not SPL (Sound pressure level) when measuring people's ability to hear different frequencies. We record the measurements in HL due to a concept called audiometric zero. Significantly more SPL is needed in the low frequencies for the average human to even hear the sound. So in dB HL we are actually experiencing lower sound intensity in the lowere pitches. This can be verified by googling "equal loundness curves in dB SPL) which will show the amounts of pressures needed for sounds to be audible in humans. I hope this helps....thanks again.
good watch, thanks again. you are a saint.
7:50 Brooo you're amazing, will definitely be checking out your sit, appreciate your video comprehension and website
Thanks for the info on these. I'd have loved to see how the do on a safety point of view.
Our traditional props are dangerous around skin but I feel like these wouldn't draw blood if they made contact. Would be interested in a short video on, maybe see how each do vs a tomato or banana?
i garuntee 100 percent they will draw blood. i dont think your realizing how powerful fpv motors are and how ridiculously fast they spin. may be slightly less damaging yes. but i garuntee it will still cut your finger to the bone in the right moment.
4s 2500kv. thats 2500rpm per volt. max voltage of 16.8v thats 42,000 rpm.
@@wubforceone Yeh, but I still want to see for myself if it does...
perhaps lost wax casting or 3d x ray polymer deposition may have good results has anyone tried the toroidal prop as a ducted fan or with a coanda effect
Very helpful testing and explanations. I think a lot of the noise of the prop (or any fan blade) comes from interaction of its shock wave with the elements of the frame supporting the motor. I would like to know how much of the noise reduction of toroidal (or any non-straight blade) prop comes from spreading out the impact of each blade's shock wave in time by making it curved, vs a reduction in tip vortices (which I assume are there regardless of what the supporting frame geometry is.) I think a lot can be done to reduce prop noise on drones by more clever design of elements close to the props that their shock waves bounce off of. An easy test would be to put a long prop axle on your test rig to move the prop away from the supporting structures, and then move objects near the blades while spinning and recording sound and displaying its frequency components using FFT.
Amateur designed 3d printed props aren’t really a valid comparison. Now what Foxeer are releasing next week would be more exciting to see a comparison of.
It's getting kind of clear that toroidal will be used for cinewhoops, places where you dont want to disturb anybody and maybe for bigger drones since 7' and forward apparently make tons of noise; while standard will still be used for freestyle, racing and probably tiny whoops for the weight difference. Great informative video
- also for "safe" props - if the tops are very circular - as has been done with outboard motor props - it could reduce (perception too) potential for harm.
I am curious as to strike applications in Ukraine. They brag about how maneuverable the FPVs are, but I suspect it is not needed. A toroidal prop being quieter may give them an offset ability to get closer before detection.
I like that they also seem not to be likely to cut someone, like it has a cage built into the prop. They would be perfect for a tinywhoop flying indoors imo. I bet the efficiency of a tinywhoop with a cage is the same as toroidal with none, and you get the quiet part as a bonus. I'd be curious to see if a tinywhoop gets sucked into a wall like a normal drone without a cage, and what its dynamics are near walls and are in crashes you know?
What is the traditional refinement process for an FPV prop? Is it (1) computer simulation or (2) making 50 versions with a thrust stand?
Wonder if it would make for a silent room fan or bathroom extractor fan?
Its interesting to compare the sound frequencies spectrum
Of the props incompare and not only dB as there is more sensitive freq to
Human ear than other
Nice video ❤
Just like most recent developments I think cinematic FPV will benefit the most here. Less awkward noise and also increased safety from not having sharp blades - especially when flying closely around people. In those applications the additional weight and lost efficiency won't outweigh the benefits, as those drones are flying slowly anyway. For classic freestyle and racing it seems we may be sticking to standard props for quite a bit longer :)
I've been waiting for a video like this, In boat prop it is so much better according to the test data with metal......One question...could you make the nasgul prop from the 3d printer also. we can see what effect the 3d printing has compared to the cast plastic prop. We need to isolate the ''3d imperfections'' variable
Could you look at doing these tests with a counterweigh prop ie the propeller is only on one side and a counterweight is on the other thus would remove the proppelor wake issues and also make it more comparable to a two blade proppelor
I would like to see what effect it would have to add a ring to the outer edge of a 5 or 6 blade prop. It should similarly reduce the tip vortices and add strength to the props
You are brilliant, thank you for sharing this. I'm sure you already know but lower frequencies get attenuated in air more than high. Would have been interesting to see the spectrum from the mic.
You are awesome!
Also, traditional props change profile as you go from center to tip to accomodate relative velocity changes with radius. I noticed the toroidal props shown here, seem to keep a high attack angle at the tips where the loop returns. This suggests to me that at least some of the noise reduction is happening because of stalling and loss of lift.
Great video, thanks for the effort. I'd love to see a traditional prop but 3Dprinted, to really check the manufacturing effect. And maybe two staggered conventional tribades, six blades would also be more whoosy" than 3
Hi how You measure thrust?
I have a resin printer. What type of resin should I use?
would the injected mold make a weight difference if you had them made the materials are not the same
I think it is better to compare props with the same blade surface area. I.e. compare a 2 loops prop with a 4 blade traditional prop, what do think about this?
cant you just lower the angle of attack right at the tip of a standard prop to stop the low pressure meeting high air pressure issue?
Does anyone make bent tip or forked tip conventional props like commercial aircraft wings?
A set for your (my) experimental--test bed AOS7 would be perfect!!
has anyone made the loudest propellers, thinking about putting whistles on mine
Very interesting and informative video. Well done demo and explanation. The other issues that are top priorities to fpv pilots. Cost, I'd wager these will cost more.
And durability, good props I can just bend back and keep on ripping. I have a feeling these toroidal props won't be so forgiving.
Happy flying everyone. 🤓
Maybe different use cases?
For the toroidal props, I would be using them in situations where I want to fly close to people, and also introduce as little 'annoying' noise as possible. Where, when I'm just rippin', and really pushing my limits as a pilot, I don't care as much about the noise, I am all about power and efficiency.
There's also less corners to get stuck behind the propellor, everything is rounded off. but yeah, they probably wont bend back with the same characteristics
@@Inertia888 or they may act like cheese graters instead of knives. 🧀😋
Im wondering when they decide a single blade with a weighted balance is the best prop for efficiency.
Stiffness of the prop is also important like glass fibre APC props or carbon fibre/wooden props.
The plastic props have the toughness for crashing but deform under load.
5 inch racing/freestlye quads, plastic 3 blade is best.
APC props for model aeroplanes or mejzelik carbon if you can afford them.
Torroidal props have their place but wont re-invent the wheel
vey nice! what is the testbench you are using for logging motor-prop data? any link?
Tyto Robotics 1585 www.tytorobotics.com/pages/series-1580-1585
@@ChrisRosser thank you!!
I suspect improvement will come with larger diameter props due to reduced wing tip velocity, I'd expect drag to have less effect on a slower spinning prop and therefore more efficient.
The faster tip speed of a bigger prop was more suited to the toroidal in the MIT testing.
Interesting- not the data I thought I would see in terms of efficiency. I would guess its because they have so much more drag, maybe because of surface finish, and just the increased area of toroidal vs. traditional? I don't think the thrust data was that surprising though, more thrust was never the goal of these props anyways. I'm excited to see how much more they can alter the sound profile of these, and if we end up seeing them on things like delivery drones in the future. Great video dude 👍
can we do winglet thingson the "normal" prop?
It would be interesting to compare with a traditional prop featuring a circular rim.
I've seen some test from the fan showdown, where he compared smoothed surface fan to unprocessed fdm fan, and there was like 1% of difference, imo main difference between 3d printed and PC prop is in it's stiffness. Also you should be running different spec motors for 5" 3-loop toroidial (comparable to 6 bladed heavy prop) something like 2506 1800kv for 4s ?
I noticed the toroidal props seem to stretch radial as motor RPM increases. Anyone else see that in the noise test?
I just saw a video on "Zipline drone silent propeller" they use staggered propellers that look like a 'V' with a little counterbalance. He goes into the science about why the propeller make noise in lower frequencies and it's quite. Toroid propellers are neat but these other props are really weird.
@ChrisRosser Your analysis are really inghtful, could I propose a few more tests?
Would be great to test comparison with toroidal prop and "iFlight F5 propeller like 3D printed" to remove the material out of the equation
In the same way would be great to test Zipline props, what borthers me most is the noise that quadcopeters produce, I would happily sacrifice a little of performance to have a quieter one
I wonder if there is a way to have variable pitch.
I was waiting to see when you were going to pull this thing apart. More practical applications I would guess would be for commercial jobs but like you said need to get some more refinements, and it would be nice if MIT would share...
similar to a QUADMOVR design minus the other worldy flight regimes he enters!! great video here for sure!!
I think it's pretty obvious that loop blades can never be as efficient as single blades. The ones we see today are also having completely wrong angle close to the tip. I'm sure you can find traditional props with vortex management optimized for noise reduction but if you optimize for noise reduction you will get less efficiency than if you optimize for efficiency which is pretty obvious...😆 So my take on the concept of torodial props ... It's just a hype. The current patent I think was from 2017 and they still haven't been able to show any better performance except possibly noise but even that I think is probably better using traditional blades optimized for noise reduction.
Which 5.5" prop do you recommend for AOS?
Hey I use the Gemfan 5536 props on my AOS 5.5 and find them really good. That's with carrying a full size GoPro. Motors I'm using now are 2208, but I was using the fpvcycle 25mm before that, I find them to be a really good fit on the aos5.5 with those props. A nice predictable throttle response 😁
…would a toroidal shape work in a ducted fan application?
And why not try the usual three-bladed propeller with the blades united by a ring. Not rotating inside, but a one-piece design and work with the corners of the ring, the upper edge is wider than the bottom and vice versa.
I'm guessing the material used to make the prop would have a wide range of differentiates.
yeah we would need to see thrust-vs-noise curves to make a judgement on noise levels though
Funny what doubling the surface area of a propeller does. I would like to see it's efficiency compared to conventional props of the same surface area.
Personally, I don't see traditional props going away for the one simple reason that is ease of manufacturing. Even if there was a marginal performance increase, it would be offset by the additional cost to retool production lines. This would be particularly true with upscaled applications such as aircraft parts, where factories would have to be retrofitted and the new propeller design would have to be FAA approved, which are both incredibly expensive endeavors.
With small drones, there is also foldability. Current small drones use foldable prop blades for compact storage.
Welp, that seals the deal for me, for the near future anyway. Thanks!
Even if they were better. we'd still have to fly off our old stock of props😜
Thanks. Test the new Foxeer toroidal props.
Will do
Congrats on pixel 🎉 :)
Has anyone tried to incorporate the “whalefin” notches to the leading edge of this type blade type?
What about putting regular props in a shroud?
Nice test! I totally seem cinewhoop migrate to these props possibly removing their ducks completely as they look a lot safer.
Why are there no traditional props with a 'winglets' or 'sharkfins' like they added to modern airplane wings? Those are also added to reduce the wing's tip vortex, AFAIK.
There are. The EMAX scimitar, for example. Great props.
Maybe you can try to obtain some of the wishbone props from Zipline for testing, too?
Nice video. Thx.
I wonder why the hell no one printed traditional props together with those toroidal ones?! Seems like this way we would compare "apples to apples" cuz manufacturing process is the same.
I did actually, but not scientific just a test hover. Funnily, my printed hex-blade drew more amps than my printed tri-loop, but it was just a hover test so no idea what the performance would be like for the rest of the thrust range.
It wasn't mentioned the toroidal props are less dangerous when dron hit a soft target. It might be an option when you need to fly you 5" relatively close to people
Damn, bad timing with the Foxeer props coming soon
I think noise is the most important thing for me. But I heard a fanless drone is call ion something i forgot the actual name.
One thing you forgot mention, these props with increase of rotative speed they will stretch out and impossible to fit on tight build , if someone try them careful they might touch each other and explode
A ducted propeller addresses tip losses and a ring propeller (and more commonly as a fan) has effectively zero tip clearance. These blades may also have forward and backward curving blade sweeps. These designs have similar advantages and limitations as a toroidal prop.
The toro just sounds more like the 8 blade props. So far personally all the advantages that iv noticed with toro I get with 8 blade and those perform better compared to printed props at least. I don't think toro will ever be a big market though I hope some injection molded toro props become available.
Yo know, I've had people complain about my 3 inch quad noise, I think I would consider them, as I'm not yet a high performance flyer.