It moves more air, more efficiently, generating more torque on the prop shaft. The motor simply doesn't have enough torque due to the propeller having more mass and air resistance.
The motor needing to do work isn’t a sign the prop is bad. Moving air takes energy, if the prop moves more air, more energy is needed. Thus motor strain
IIRC, 10 decibels is a doubling/halving of the noise being measured. A reduction of 6 decibels isn't quite halving the amount of noise, but a 35%-ish reduction in noise is still significant.
This is misleading. Its power is about 4 time lower and amplitude about 2, but our perception of sound is also inversely exponential, meaning that our perception is roughly linear with the metering. It's worth noting, though, that there frequencies that mostly drop here are higher frequencies which aren't correctly measure using dba.
@@twylanaythias6dB is in fact equal to halving or doubling in SPL level, voltage, and in some other things like when measuring ratios. You can corroborate this with a simple formula of dB amount = 20Log( X / X ref). In this case 20Log(2/1) is equal to 6dB and actually 10dB would be more like triplicating the noise level. [20Log(3/1) = 9.54dB]
Its not only the -6 dB that makes it feel quieter, but also the reduced frequency peak and uniform noise spectrum, similar to how they made car tires less noisy.
It's not only the decibels that impact the noise. The toroidsl propeller smoothes out the peaks in frequency of the nornal propeller making it more comfortable to listen to
Yeah, also, you can’t just make a toroidal shape and expect it to be good. There’s a fair amount of engineering involving the pitch and angle attack. The fact that a thrown together experiment matched up to a calculated prop at all is impressive.
sometimes good craftsmanship can overpower poor research. Not saying it's proper, but definitely cool and worth something yeah@@grubalaboocreosote4774
@@MONKEYGUY8504 symmetry has nothing to do with it. It just produces a different sound because it interacts with the air differently than a straight propellor
@@rossmcdonagh1554set to the same RPM yes, but it doesn't mean they're achieving the same rpm. If a different propeller has more drag it's just going to go slower. The only variable that's the exact same is the power of the little plane.
@@j-schnab6338 that wasn't even the point why I suggested it but yes that also comes in handy. I just think it's another good measure to compare the noise level since we don't really car that much about rpm but more about thrust that just happens to be higher at higher rpm.
There is another problem at play! Another guy on RUclips was putting together his own RC boat, and tried those types of propellers. He found that there’s quite a difference depending on whether they’re FDM printed(like you’ve done here), or Resin Printed. Then again, he was messing with submerged propellers; any residual air could mess with its performance.
must be talking about RCTestflight actually i have the list of RUclipsrs testing such technologys and it's growing with dates for chronological timeline frequency of information spread and advancement 😊 the real bonus is weed free so your small lack in efficiency becomes a heavy improvement on efficiency for heavier weeded areas boating or i guess for planes bird strike strength etc though you aren't trying to tangle with such obstacles
The edges of those propellers looked squared off and blunt while the traditional propeller looked more refined. If you want a more fair test, you need to print your own standard propeller to the same materials and standards as the toroidal. The toroidal propellers I’ve seen were precision milled to extreme precision using a 5 axis CNC to achieve their superior numbers.
@benji3900 simply because that's the only real world scenario that matters if you are focused on the sound alone. The traditional propeller makes alot more thrust, with only slightly more decibels. In the real world situation, where you need the same amount of thrust for these to be equal in performance, the traditional propeller will probably be quieter.
I think the reason the toroidal propellers have some issues is the weights at the tip as they loop over into the next propeller. You might need to drill holes there to allow some air to fall out through it. If not that, then you might need to change up the shapes at the tips to account for air manipulation.
just a reminder to everyone that a difference in 3 decibels is a multiplier of 2, meaning that 6 decibels is a multiplier of 4. Edit: Big thanks to yt for telling me that a whole 2 people liked my comment. It really helped me a lot to know.
i think the mass distribution is affecting the moment of inertia and requiring more energy to spin the toroidal one. you may need to print it again with a different design to see better results
Yeah can you can see all the rough around the edges and extrusion which is spoiling airflow, a more refined design like the initial standard prop would be interesting.
@@TowerCrisisI can’t see that if you have a dremel and you spin it and apply lots of friction it won’t spin as fast. Or if you add a lot of weight to it. Now a car with steel wheels and the same car with magnesium wheels will spin the same because of the gears and the tiny amount of total output that’s used to spin them.
The toroidal propeller should be much quieter, the reason why your propeller sounds as loud is because the layer lines on your 3d print are negating its advantage because its causing a lot of wake and turbulence, I suggest that you make the layer height as thin as possible, then sand it smooth and add a layer of a filler like spackle or find a way to make it smooth to the touch, then polish it, now it should work.
The major advantage of a toroidal prop is it improves efficiency by reducing tip vortex, in case of a drone you have multiple vortex interacting making them less effective because of the prop arrangement. The down sides of this prop is spinning weight. Also more prop blades do not make a prop better, they spread the horsepower out to improve energy transfer so more are needed if the plane is over power loading the prop it is why the 800hp spitfire had a wooden fix pitch prop, and the later 2000+ hp model had two 3 blade counter rotating monster of a prop to make a 6blade prop with no P factor. A low power plan works better with a more efficient 2 blade prop.
It would be interesting to reduce the throttle on the regular propeller to match the thrust of the torodial ones. Then you could compare the noise levels at identical thrust. Also measuring current draw would be informative.
That would indicate a designed inefficiency in fuel and power, which in turn would be better solved by just flying slower or getting better headphones. As for civilian noise complaints, just fly higher.
You did not address weight. If a propeller is heavier, it will spin slower given the same torque. That would explain the quieter sound and decreased thrust.
@@goofballbiscuits3647 Top speed is affected way more by drag and not weight, weight is more relevant for acceleration and climb rate. Top speed will only be lowered if drag increases, which may not happen with a small increase in weight.
@@goofballbiscuits3647 Top speed is affected way more by drag and not weight, weight is more relevant for acceleration and climb rate. Top speed will only be lowered if drag increases, which may not happen with a small increase in weight.
@@reinbeers5322 Sure, acceleration is more affected but saying only acceleration is affected it flat out wrong. This isn't a zero-sum gain. Propeller efficiency changes with airspeed. Change the propeller, expect that power band to change. Propeller efficiency can also allow the motor to be over-revved. Propeller length should be determined by the *_motor_*. He did not change that iirc. Only changing the propeller is going to affect more than just acceleration. It will affect the entire passage through the medium. As displacement of air is also critical, not just drag. "Better to move a lot of air, a little."
I think what people don't immediately realize is that the 5 bladed toroidal prop being 6dB quieter is 4x quieter than the standard prop. That is an incredibly substantial difference.
You need to 3d print a standard propellor for this to be a fair test. The weight and surface of a printer will never be the same. I still expect the standard twin blade to win. Also, we should remember that because of the geometry of toroidal propellors, it is not perfectly accurate to describe them as "3-bladed" or "5-bladed." A better terminology could be "3-fold rotational symmetry" or "5-fold rotational symmetry." These blades have more like 6 blades and 8-10 blades worth of surface area respectively.
For those who don't know being 5 db quieter is a little more than a third as loud 10^.5 it's because the math for db is logarithmic meaning that every 10 bd is ten times louder or 10^1 20 bd quieter is 100 times quieter or 10^2 and 30 bd quieter is 1000 times quieter or 10^3
You are wrong. Psychoacoustics isn't an exact science because it's so subjective. In general 6-10db difference is considered half or twice as loud but it differs from person to person. Also it's really hard to tell when something is "twice as loud". What you're referencing with 10, 100 and 1000 times higher is the change in effective sound pressure in Pascal. The entire point of the db-scale is to get rid of the logarithmic factor because our ears sensitivity to sound pressure follows a logarithmic scale. And working with pascal directly is impractical. 0db is the hearing threshold of the average human.
@@NiliMotoI was hoping someone commented this. It's also why I personally go by the 6db scale as that's how SPL is measured... and that's all I care about :D
How thin can you print without compromising rigidity? Lessening the mass of the blades and moving the center of gravity to the fulcrum would be the best strategy to both increase inertia and lessen drag.
You need to account for the weight differences and drag too...causing the motor to turn slower RPM, hence quieter and less thrust. Match RPM and then test.
Important thing missing from the thrust measurement is a simultaneous measure of power being drawn. The toroidal props could be weaker but drawing less power making them more efficient or weaker and drawing more power making them even worse. It would be interesting to see this measured together for a more complete picture.
I’d imagine the mass, especially at the tips is MUCH higher so the lower thrust and sound is probably due to a lower RPM, and power draw would likely be higher
Im trying to understand this comment. The motor should be drawing a fairly constant amount of power regardless of what its driving. The lowered performance would be some summation of the properties of the printed propeller making it harder for the motor to apply torque to. I think to make this test "fair", one should iterating the design of the toroidal propeller itself. By that i mean, the printed propellers seem suboptimal compared to the original design. My intuition tells me if he played with the mass, cross section, raidus and/or print material he'd see better results. Essentially he needs to lower the Mass moment of inertia to make the propeller easier to spin, then he can start playing woth thrust properties.
@@h34dshotgl0re By power you mean amps, right? I don’t know a ton about how to calculate amps from prop mass/pitch/size, but I do know a bit about power consumption in general. A motor has a KV rating which for our purposes is the number of RPMs the motor will spin at a specific voltage. The amount of current the motor is going to need to do that is going to change based on the load. So no prop requires few amps, big prop requires big amps OR big prop pitch (more air pushed per rotation) also requires big amps. So you’re completely right, they need to test different prop geometries to actually see if they can optimize the design to be competitive. I just don’t think it’s going to be useful to try to compare a homemade design to something designed by the pros, then claim conclusions based on an amateur attempt :(
It's worth noting that the toroidal props were designed for drones, where sound and turbulence can be annoying. The lack of a clearly defined tip makes for less turbulence and thus easier landings.
As far as I know, decibels are measured one meter away from the source. If you put it right next to the source.... Measurement is compromised. Read more about what the decibel means and how to measure it.
I like this type of videos, let's make them normal. No clickbait, strait to the point well filmed with captions so i can watch it while my baby daughter goes to sleep. Nice
In car audio, every time you double the watts, it adds 3db. If a pair of 12" subwoofers hit 117db with 500 watts, then only 125w will hit 111db. So it might seem counterintuitive, but -6db is 75% quieter.
It's important to note that 6 decibels is actually a big difference. For reference, every 10 decibels is double the volume. This means going from 10 to 20 decibels would result in a 100% increase in noise.
3dB is about the smallest sound level change you can discern The sound ENERGY doubles or halves with a 3dB change, but eyes and ears have logarithmic intensity responses, not linear
@@definingslawek4731 if you 3d printed a normal one it probably wouldn't fare well. That rough surface will have a high Renoylds number and be generating a lot of noise/drag I'd be highly tempted to 3d print blades using my SLA printer rather than relying on any kind of extruder. This can produce a surface which is almost perfect (and flexible with resin tuning, I've done this for "clothespeg" type electronics clips otherwise they snap after a couple of uses) and can be further improved with acetone treatment before final hardening
If I remember correctly toroidal propellers are supposed to be more efficient, not necessarily more powerful. They are more like a side step to traditional propellers than an upgrade. A more accurate way to rate them would be to record audio from farther away and record how long battery life’s last.
The two biggest factors of a propellers efficiency is the angle of attack and the diameter. Two blade propellers are typically more efficient as well, but louder.
Noise is not just about decibles, it is also the range of the different tones. That's what sound insulation does for rooms and cars does. Basically cleans the spikes in tones
It logically follows that toroidal propellers would both be quieter and produce less static thrust as the key factor for both is cavitation. While generally discussed in context of liquid-based propellers, cavitation is the variegation of pressures created through a medium used as the basis for propulsion. In water, it is more specifically caused by areas of pressure low enough to release vapor - usually suspended gasses, though sometimes reducing pressure below the liquid's vapor point. This disruption of nominally-stable pressure creates vibrations which result in noise. As the toroidal propeller has both greater surface area and is more 'regular', it results in less cavitation - hence, producing more noise. I'm sure there's a more precise term but, essentially, cavitation is turbulence. Turbulent air is 'more solid' than non-turbulent air, providing more resistance against the thrust created by the conventional propeller; as the toroidal propeller produces less cavitation (and less turbulence), there's less resistance pushing back against the thrust it provides. During flight, the plane is constantly moving through air which has yet to be affected by the propeller. Hence, the turbulence/cavitation caused by the propeller is less a factor in the amount of force imparted by the propeller's thrust pushing against it. I'm sure there's a more proper explanation for this phenomenon, but I haven't studied this field enough to know what it is.
By increasing the number of blades, you must reduce the diameter of the propeller. Each more blade is 1" less in diameter. Lower thrust may be caused by too much load on the engine, which results in lower revolutions. I'm waiting for further tests;)
It's not about which is better, it's about what application would be good for them. They'd be perfect for Paramotor Planes, not much power is necessary, but being quiet would be a huge improvement for them.
It looks like the regular propeller is made from a different material than the propellers. I would recommend printing a regular propeller with the same material, to test the toroidal prints against. This will ensure consistency in your testing
I think the toroidal propeller was designed for maximum efficiency in the mid-range of engine rpm. Instead of testing thrust at the highest RPM, maybe test thrust at lower RPM to see if the toroidal propeller generates more thrust with less power. Air also has different fluid dynamics than air. I believe the point of the toroidal propeller is to minimize cavitation compared to a regular propeller, and that affect may not be as influential to noise and engine efficiency in air as it is in water. You put in a lot of work with this experiment. I'd love to see more experiments with these same propellers!
If you match the thrust the sound goes back to normal. They aren't quieter. They just have their noise more spread out over more frequencies that are less audible to humans, there quieter. Somewhat like the tread on tires going from blocky to variable spacing and angular shapes to spread out the impact and therefore spread out the noise.
I've seen this test so many times, and they always use 3d printers for the toroidal propellers, which completely skews the results. Regular propellers are thinner and lighter while also being stronger, they're weight balanced, have proper air foils, and have a smooth surface. 3d printed propellers are almost never perfectly weight balanced, which creates a lot of vibrations and motor resistance on top of the extra weight and thickness. They also often don't have proper air foils, but just flat, uneven surfaces with right angle edges as yours did, which creates a lot of vortexing and wind resistance.
The toroidal propellors also remove the higher pitch sounds from the propellers, which makes us percieve them as being even quieter even without a huge change in decibel level.
I think your toroidal propellers were partially stalling out due to the air not really having the linear flow. Trying them out in the open air, I would see which one was faster. I have heard of racing and fighter planes having a prop stall. I’d like to know how fast they really go.
You should compare the motor current as well. Efficiency is also very important thing. I believe that flower-type propellers were rotating slower, so this is why they were less noise and less throsty.
It seems like the tips are the problem, not enough "bite" and directed thrust. The area where the blade folds back over itself, at the tip, needs a more aggressive shape. If you look out from the center along the blade the end should be grabbing the air on the outside and redirecting it backwards. Regular blade tips are thin for less resistance. The toro-blade has material there. Is it dead weight or another useful surface?
Nice test! I think you should also 3D print the regular propeller from the same material you made the toroidal propellers, perhaps the finish has an effect on the final results.
Change the pitch angle of the blades. The leading blade at a less of a pitch than the following blade. The leading of the loop is pushing the air out of the way so the following edge has less volume available within the blade space. If you have the end of each loop also pitched in a way to focus the air on the outside of the loop into the inner part of the loop.
Drag comes in many forms. Just as wing shapes create different amounts of drag, a prop with more surface area will create more drag, causing the engine (or motor, if electric) to work harder. You will likely notice reduced run time from your battery if it is electric. This is why real GA aircraft stick with the simple dual blade prop design.
A fixed pitch propeller works optimally in a given airflow speed. This thrust comparison test shows only the zero airflow speed results without RPM regulation of the motor, so the different prop blade drag values also gave different RPMs. You cannot really compare these in this way.
Thing about decibels. Each one is an EXPONENTIAL increase. Meaning going from 100 dB to 101dB is actually 100% louder. Food for thought when there's a 6dB decrease.
Would be interesting to check the Ratio Thrust/Amps. If they produce 25% less thrust, but 30% less power usage, they'd still be better, and just upgrade the motor to compensate for the loss.
From just looking at the video, it appears the pitch is more aggressive on the 3d printed ones AND the edges that cut through the air aren’t as sharp as the two blade. If you were to experiment with those two features, you could beat the regular propeller and be even quieter.
Can you try weight normalizing them? The turoidal ones can have thinner blades because they have stronger structures. I'm wondering if the heavier 3D printed blades had an impact on thrust.
The problem here is that the outer tips/edge of the toriodial propellers create unstable turbulent airflow at a far greater rate than a traditional propeller. That's where you are loosing your power and is the reason we do not use them on airplanes.
This is true in full size aircraft as well. As an example, Beech King Airs with the standard 3 bladed props are louder inside and out, but exhibit higher top speeds. Whereas those fitted with 5 blade upgrades from a company like Raisbeck tend to have better climb performance and a quieter ride in the cabin but also suffer a slight cruise speed penalty.
The Blade cross section on the toroidal props are not as "wing-like" as the stock prop. This would limit or eliminate the "Bernoulli Effect" allowing for more thrust from the standard prop. This is vastly more important in water than air. Plus, having MORE surface area to generate thrust, the Tordial props should, in fact, be more powerful.
My advice you should have compared also is three blade propeller with and without the toroidal version. Because more blades request more torque. And since you are limited with your engine. The maximum revolutions are lower with higher blade numbers.
Don't forget that the decibel scale represents a doubling every three decibels because it's logarithmic so the five blade toroidal was a factor of four quieter than the standard propeller. I suspect that some of this absence of noise correlates with an absence of thrust created
should have testing thrust normalized to noise, since that's the metric you're interested in. Are they quieter? Are they weaker? For the same kg of thrust, do you get less noise?
My dad changed from 4 blade propellers to 5 blades on his boat, the F/V SAGA. He ended up needing more powerful main engines to turn them efficiently. I wonder if this could be a similar situation.
As a person trained in basic aerodynamics and with real aircraft maintenance experience I can say that propellers are specically formed in a way to get as much "bite" on the air as possible as pulls t the plane through the air while minimizing drag. It seems that the new propellers have a lower pull and higher parasitic drag coiefficients. Still an interesting idea though.
Anyone in the hobby knows thrust is largely decided by the pitch of the propeller. Since you should be using a brushless motor, RPMs will be constant, so refining the pitch of the rotors till they match either the thrust, or the power draw and then testing would be a true test.
Did you actually designed and built them correctly tho? A lot of RUclipsrs are building toroidal props because one marine company sells them and a univeristy made a project based on toroidal propellers, but those youtubers did not do the same amount R&D as the marine company and university. You can't expect the results would be the same.
6dB doesnt sound like a huge reduction, but it's a logarithmic scale. Every 3db is effectively double the air pressure. Air pressure and percieved volume dont line up exactly but this is still almost 1/3 quieter.
maybe those new blade designs have a better efficiency long term, with "fuel" consumption and such, but as several have pointed out either make a control copy of the original 1 blade propellor, so it's mass with the same material can be measured against the toroidals, or smooth and slick the new blades to match the original one. My observation anyways.
Try 3d print your regular propeller from the same material. For more acurraci. And plane may need some tuning too I gues. It is optimalized for this regular type
In terms of noise level, I notice that the edges of the toroid propeller ribbons are sharply squared-off. If possible, it might make sense to make those edges smoothly curved.
I just bought that Carbon Cub. And um. I crashed it on my first flight. I don't have that much free space to fly and the starboard wheel fell of during take off... Another thing was that I didn't realize how much the airplane relied on thrust. It doesn't seem to glide as well as I hoped it to.
Adjust the pitch of your toroidal, and tune for the desired thrust. Think of a constant speed prop - you need “Fine” pitch for take off, and once airborne you back off the pitch for cruising speed. As your little toy doesn’t have adjustable pitch, you have to set it up on the ground.
Have you compared with 2 toroidal bladed propellers? Based on your 3 and 5-bladed toroidals data, the 2-bladed toroidal propellers may be equivalent with the regular 2-bladed propeller.
The reason they are better is because in water they avoid making vacuum bubbles. This isn't an issue in the air (or maybe at some extreme spin it is?! who knows??) So out of water there is no reason to think they'd be better. In water however they very much are....the issue is the production cost is much higher at the moment.
You can Hear it straining the engine more with the fancy propeller 😅
Maybe try to Put holes in the end of the toroidal to let air escape? Or utilize that air cant slip off the ends like a propeller
Engine that’s a brushless motor lmao
It moves more air, more efficiently, generating more torque on the prop shaft.
The motor simply doesn't have enough torque due to the propeller having more mass and air resistance.
The motor needing to do work isn’t a sign the prop is bad. Moving air takes energy, if the prop moves more air, more energy is needed. Thus motor strain
if you read the paper from MIT, it moves more air but uses just as much energy to do so
For a fair testing you should have printed the normal Rotor it self also (not smooth carbon premade)
100%
^ this
Thats a work around i didnt think of, but Glad im not the only one thinking about the 3d print vs the factory molded
yup. at the least.
Also should have tested the normal prop with 3 and 5 blades too
Print in ABS and smooth in acetone. That got me the power I was looking for from these.
note that 6 decibels is a MASSIVE difference--the decibel system isn't linear, meaning 6 decibels is actually halving the amount of noise.
IIRC, 10 decibels is a doubling/halving of the noise being measured. A reduction of 6 decibels isn't quite halving the amount of noise, but a 35%-ish reduction in noise is still significant.
This is misleading. Its power is about 4 time lower and amplitude about 2, but our perception of sound is also inversely exponential, meaning that our perception is roughly linear with the metering.
It's worth noting, though, that there frequencies that mostly drop here are higher frequencies which aren't correctly measure using dba.
@@twylanaythias6dB is in fact equal to halving or doubling in SPL level, voltage, and in some other things like when measuring ratios. You can corroborate this with a simple formula of dB amount = 20Log( X / X ref). In this case 20Log(2/1) is equal to 6dB and actually 10dB would be more like triplicating the noise level. [20Log(3/1) = 9.54dB]
WHAT?!?
Not quite half...... but you are thinking correctly that it's non linear reduction. More like 15%.
Its not only the -6 dB that makes it feel quieter, but also the reduced frequency peak and uniform noise spectrum, similar to how they made car tires less noisy.
-6db is a 75% reduction in noise, as the decibel scale is logarithmic
Um conhecido meu ajudou a escrever um livro sobre acustica em automoveis pela UFSC. Voce conhece este livro? É um dos poucos produzidos no Brasil.
And there is no way that they’re in the +100db range. That’s louder than a rock concert.
@@wartortilla2819 it's measured right at the propeller so it's totally possible. Sound dissapates quickly with distance.
For 25% less efficient and 25% slower? No thanks.
The specific shape makes all the difference. Unless it’s optimized for medium and rpms this won’t show the real power of the toroidal propeller.
They were debunked a good while ago now, they work but they aren’t anything special.
That also applies to normal propellers…
True, I haven't done much optimization, i just guessed a shape that may work.
@@nlmaster9811 source?
@@nlmaster9811 it don't make sense! Regular ones lose wind sideways. Weren't optimised
It's not only the decibels that impact the noise. The toroidsl propeller smoothes out the peaks in frequency of the nornal propeller making it more comfortable to listen to
Yeah, also, you can’t just make a toroidal shape and expect it to be good. There’s a fair amount of engineering involving the pitch and angle attack. The fact that a thrown together experiment matched up to a calculated prop at all is impressive.
sometimes good craftsmanship can overpower poor research. Not saying it's proper, but definitely cool and worth something yeah@@grubalaboocreosote4774
@grubalaboocreosote4774 Yeah the ridges from printing already make more noise by creating resistance
Deleting my comment because apparently the one it was referring to was deleted.
@@MONKEYGUY8504 symmetry has nothing to do with it. It just produces a different sound because it interacts with the air differently than a straight propellor
You should slow down the regular propeller until it produces the same thrust as the toroidal and then compare the noise again.
Are they not set to the same rpm?
@@rossmcdonagh1554 Yes and I just suggested a different comparison.
@@rossmcdonagh1554set to the same RPM yes, but it doesn't mean they're achieving the same rpm. If a different propeller has more drag it's just going to go slower. The only variable that's the exact same is the power of the little plane.
That's a good idea. People always forget to remove as many variables as possible for a real comparison.
@@j-schnab6338 that wasn't even the point why I suggested it but yes that also comes in handy. I just think it's another good measure to compare the noise level since we don't really car that much about rpm but more about thrust that just happens to be higher at higher rpm.
There is another problem at play!
Another guy on RUclips was putting together his own RC boat, and tried those types of propellers. He found that there’s quite a difference depending on whether they’re FDM printed(like you’ve done here), or Resin Printed.
Then again, he was messing with submerged propellers; any residual air could mess with its performance.
must be talking about RCTestflight actually i have the list of RUclipsrs testing such technologys and it's growing with dates for chronological timeline frequency of information spread and advancement 😊 the real bonus is weed free so your small lack in efficiency becomes a heavy improvement on efficiency for heavier weeded areas boating or i guess for planes bird strike strength etc though you aren't trying to tangle with such obstacles
infinity ward finna start producing planes 💀💀
The treyarch logo
The edges of those propellers looked squared off and blunt while the traditional propeller looked more refined. If you want a more fair test, you need to print your own standard propeller to the same materials and standards as the toroidal. The toroidal propellers I’ve seen were precision milled to extreme precision using a 5 axis CNC to achieve their superior numbers.
Yea the surface finish is definitely not doing the prop any good.
@@makermandanthe extra weight wouldn't help either.
In scientific testing they are more efficient.
But to counter your statement, the propellers should be run with their speeds adjusted to matching thrust as well.
@@outlawgamingrp why would you adjust that? They should all be run at whatever power that motor can produce.
@benji3900 simply because that's the only real world scenario that matters if you are focused on the sound alone. The traditional propeller makes alot more thrust, with only slightly more decibels. In the real world situation, where you need the same amount of thrust for these to be equal in performance, the traditional propeller will probably be quieter.
To make a fair comparison you should also 3D print a 1/1 replica of the original propeller. Layer lines, material and surface finish affect so much
in addition, the shape of each blade should be like a wing. the vid looks like it has a square edge from the printer.
yeah im so tired of people printing garbage then testing it and acting like it is representative of anything
Exactly my thought. Comparing FDM to IM isnt accounting for necessary variables
I never thought treyarch would make a propeller
Thank god I wasn’t the only one
Was gonna say that 😂
Lmao
Thought the same thing
Was gonna comment this nice
I think the reason the toroidal propellers have some issues is the weights at the tip as they loop over into the next propeller. You might need to drill holes there to allow some air to fall out through it. If not that, then you might need to change up the shapes at the tips to account for air manipulation.
Treyarch blade mentioned 🙌🏻
just a reminder to everyone that a difference in 3 decibels is a multiplier of 2, meaning that 6 decibels is a multiplier of 4.
Edit: Big thanks to yt for telling me that a whole 2 people liked my comment. It really helped me a lot to know.
Facts
😂
Именно этот комментарий я искал. Почему эта информация недоступна широким массам?
It's 10 decibels
@darthpotwet2668 Ten decibels is a multiplier of 10. 3 decibels is a multiplier of 2.
The ultimate test is motor current draw vs thrust. Otherwise, there are too many other variables in your experiment... which is really cool BTW.
Thanks!
i'd be interested to know their masses, as well.
Years ago, I was recruiting for an aircraft design team, and this was one of the questions we would ask. Most people were surprised by the answer.
The toroidal propellers are designed to drop off sound over distance faster....@@makermandan
i think the mass distribution is affecting the moment of inertia and requiring more energy to spin the toroidal one.
you may need to print it again with a different design to see better results
That is true, it’s a lot heavier
That should only affect how much time and energy it takes to get it up to speed, the top speed is unchanged by just increasing mass.
@@makermandan you should always compare them to a similar sized prop, thats also 3d printed
Yeah can you can see all the rough around the edges and extrusion which is spoiling airflow, a more refined design like the initial standard prop would be interesting.
@@TowerCrisisI can’t see that if you have a dremel and you spin it and apply lots of friction it won’t spin as fast. Or if you add a lot of weight to it. Now a car with steel wheels and the same car with magnesium wheels will spin the same because of the gears and the tiny amount of total output that’s used to spin them.
The toroidal propeller should be much quieter, the reason why your propeller sounds as loud is because the layer lines on your 3d print are negating its advantage because its causing a lot of wake and turbulence, I suggest that you make the layer height as thin as possible, then sand it smooth and add a layer of a filler like spackle or find a way to make it smooth to the touch, then polish it, now it should work.
The major advantage of a toroidal prop is it improves efficiency by reducing tip vortex, in case of a drone you have multiple vortex interacting making them less effective because of the prop arrangement. The down sides of this prop is spinning weight. Also more prop blades do not make a prop better, they spread the horsepower out to improve energy transfer so more are needed if the plane is over power loading the prop it is why the 800hp spitfire had a wooden fix pitch prop, and the later 2000+ hp model had two 3 blade counter rotating monster of a prop to make a 6blade prop with no P factor. A low power plan works better with a more efficient 2 blade prop.
It would be interesting to reduce the throttle on the regular propeller to match the thrust of the torodial ones. Then you could compare the noise levels at identical thrust. Also measuring current draw would be informative.
That would indicate a designed inefficiency in fuel and power, which in turn would be better solved by just flying slower or getting better headphones. As for civilian noise complaints, just fly higher.
You did not address weight. If a propeller is heavier, it will spin slower given the same torque. That would explain the quieter sound and decreased thrust.
It'll only accelerate slower, the rest is down to drag.
@@reinbeers5322Acceleration *_and_* maximum velocity would also be reduced. Those are entirely different, and we are trying to fly in the end.
@@goofballbiscuits3647 Top speed is affected way more by drag and not weight, weight is more relevant for acceleration and climb rate.
Top speed will only be lowered if drag increases, which may not happen with a small increase in weight.
@@goofballbiscuits3647 Top speed is affected way more by drag and not weight, weight is more relevant for acceleration and climb rate.
Top speed will only be lowered if drag increases, which may not happen with a small increase in weight.
@@reinbeers5322 Sure, acceleration is more affected but saying only acceleration is affected it flat out wrong. This isn't a zero-sum gain. Propeller efficiency changes with airspeed. Change the propeller, expect that power band to change. Propeller efficiency can also allow the motor to be over-revved.
Propeller length should be determined by the *_motor_*. He did not change that iirc.
Only changing the propeller is going to affect more than just acceleration. It will affect the entire passage through the medium. As displacement of air is also critical, not just drag.
"Better to move a lot of air, a little."
I think what people don't immediately realize is that the 5 bladed toroidal prop being 6dB quieter is 4x quieter than the standard prop. That is an incredibly substantial difference.
This is a genuine question, how is it 4x?
@@seenlenzdB is a logarithmic scale, a 3dB difference means a difference of a factor of two of its power
@@nicholasm5184 aaaaah, right. Thanks man.
PC fan tests prove you can reduce sound significantly, and likely improve everything else too.
You need to 3d print a standard propellor for this to be a fair test. The weight and surface of a printer will never be the same. I still expect the standard twin blade to win. Also, we should remember that because of the geometry of toroidal propellors, it is not perfectly accurate to describe them as "3-bladed" or "5-bladed." A better terminology could be "3-fold rotational symmetry" or "5-fold rotational symmetry." These blades have more like 6 blades and 8-10 blades worth of surface area respectively.
For those who don't know being 5 db quieter is a little more than a third as loud 10^.5
it's because the math for db is logarithmic meaning that every 10 bd is ten times louder or 10^1 20 bd quieter is 100 times quieter or 10^2 and 30 bd quieter is 1000 times quieter or 10^3
You are wrong. Psychoacoustics isn't an exact science because it's so subjective. In general 6-10db difference is considered half or twice as loud but it differs from person to person. Also it's really hard to tell when something is "twice as loud".
What you're referencing with 10, 100 and 1000 times higher is the change in effective sound pressure in Pascal. The entire point of the db-scale is to get rid of the logarithmic factor because our ears sensitivity to sound pressure follows a logarithmic scale. And working with pascal directly is impractical. 0db is the hearing threshold of the average human.
What the heck?
Is this math?
Nah,I m definitely not getting ANY certificate in academy now 💀
@@NiliMotoI was hoping someone commented this. It's also why I personally go by the 6db scale as that's how SPL is measured... and that's all I care about :D
@@NiliMoto3db is half the power, db scale IS logarithmic, not to get rid of it. It's math.
@@NiliMoto he are not wrong, the sound pressure diff in dB will do hearing damages at proportional levels
How thin can you print without compromising rigidity? Lessening the mass of the blades and moving the center of gravity to the fulcrum would be the best strategy to both increase inertia and lessen drag.
👍🏽 love engineers. Blue collar keeps the world running, white collar advances the world
Increase inertia?
Also, please compare the amp draw vs thrust. It’s possible the toroidal props have a lower max thrust but produce more thrust per amp.
Well if the motor slows it draws more current. They might produce more thrust at the same rpm, but so does any bigger propeller.
The difference between 3d printed an injection molded is shockingly significant when talking about aerodynamics.
remember, decibles are a logrithmic scale. 6db is about 50% quieter.
50% less noise for 25% less thrust seems a decent deal to me
You need to account for the weight differences and drag too...causing the motor to turn slower RPM, hence quieter and less thrust. Match RPM and then test.
Important thing missing from the thrust measurement is a simultaneous measure of power being drawn. The toroidal props could be weaker but drawing less power making them more efficient or weaker and drawing more power making them even worse. It would be interesting to see this measured together for a more complete picture.
I’d imagine the mass, especially at the tips is MUCH higher so the lower thrust and sound is probably due to a lower RPM, and power draw would likely be higher
Im trying to understand this comment. The motor should be drawing a fairly constant amount of power regardless of what its driving. The lowered performance would be some summation of the properties of the printed propeller making it harder for the motor to apply torque to.
I think to make this test "fair", one should iterating the design of the toroidal propeller itself.
By that i mean, the printed propellers seem suboptimal compared to the original design. My intuition tells me if he played with the mass, cross section, raidus and/or print material he'd see better results. Essentially he needs to lower the Mass moment of inertia to make the propeller easier to spin, then he can start playing woth thrust properties.
@@h34dshotgl0re By power you mean amps, right? I don’t know a ton about how to calculate amps from prop mass/pitch/size, but I do know a bit about power consumption in general. A motor has a KV rating which for our purposes is the number of RPMs the motor will spin at a specific voltage. The amount of current the motor is going to need to do that is going to change based on the load. So no prop requires few amps, big prop requires big amps OR big prop pitch (more air pushed per rotation) also requires big amps.
So you’re completely right, they need to test different prop geometries to actually see if they can optimize the design to be competitive. I just don’t think it’s going to be useful to try to compare a homemade design to something designed by the pros, then claim conclusions based on an amateur attempt :(
True, I don't have the equipment to measure the current draw but I can look into it for future testing.
@@h34dshotgl0reWhy do you think a motor should draw the same amount of power regardless of what it’s driving? I’m fairly sure that’s totally wrong.
It's worth noting that the toroidal props were designed for drones, where sound and turbulence can be annoying. The lack of a clearly defined tip makes for less turbulence and thus easier landings.
As far as I know, decibels are measured one meter away from the source. If you put it right next to the source.... Measurement is compromised. Read more about what the decibel means and how to measure it.
You still have sharp edges and rough surfaces on the 3d printed ones. It would be interesting if you measured rpm as well.
I like this type of videos, let's make them normal. No clickbait, strait to the point well filmed with captions so i can watch it while my baby daughter goes to sleep. Nice
You may have to optimize and experiment with different propeller types to find the best kind, as some might not be good for flight compared to others.
Just a question to check, was your regular propeller also 3D printed. Because that may introduce some additional noise and performance issues.
In car audio, every time you double the watts, it adds 3db. If a pair of 12" subwoofers hit 117db with 500 watts, then only 125w will hit 111db. So it might seem counterintuitive, but -6db is 75% quieter.
It's important to note that 6 decibels is actually a big difference. For reference, every 10 decibels is double the volume. This means going from 10 to 20 decibels would result in a 100% increase in noise.
Be interesting to measure the noise level of the standard prop running at a lower speed such that it matches the thrust of the fancy prop.
Id imagine the regular prop still retains a higher pitch timbre.
@@makermandan why imagine? You're set up to test exactly this and it's a valid point.
A sounds volume doubles every 3 decibles, so the difference between the propellers was massive
3dB is about the smallest sound level change you can discern
The sound ENERGY doubles or halves with a 3dB change, but eyes and ears have logarithmic intensity responses, not linear
@@miscbits6399meaning it takes 10db to double the perceived volume of a sound, not 3db :)
The normal one is actually quieter when normalised for thrust generated.
@@definingslawek4731 if you 3d printed a normal one it probably wouldn't fare well. That rough surface will have a high Renoylds number and be generating a lot of noise/drag
I'd be highly tempted to 3d print blades using my SLA printer rather than relying on any kind of extruder. This can produce a surface which is almost perfect (and flexible with resin tuning, I've done this for "clothespeg" type electronics clips otherwise they snap after a couple of uses) and can be further improved with acetone treatment before final hardening
@@nathanblanchard8897 well, 50% is still a lot tho
If I remember correctly toroidal propellers are supposed to be more efficient, not necessarily more powerful. They are more like a side step to traditional propellers than an upgrade. A more accurate way to rate them would be to record audio from farther away and record how long battery life’s last.
The two biggest factors of a propellers efficiency is the angle of attack and the diameter. Two blade propellers are typically more efficient as well, but louder.
I would also sand or use resin to fill the grooves of the print so they are smoother. should help improve performance and reduce sound as well.
Spinning flower propeller 😊
also, the db scale is exponential so 6db are A LOT when above 100db
you gotta polish them smooth, there will be less turbulence meaning less noise and less power wasted on air friction
Noise is not just about decibles, it is also the range of the different tones. That's what sound insulation does for rooms and cars does. Basically cleans the spikes in tones
It logically follows that toroidal propellers would both be quieter and produce less static thrust as the key factor for both is cavitation.
While generally discussed in context of liquid-based propellers, cavitation is the variegation of pressures created through a medium used as the basis for propulsion. In water, it is more specifically caused by areas of pressure low enough to release vapor - usually suspended gasses, though sometimes reducing pressure below the liquid's vapor point. This disruption of nominally-stable pressure creates vibrations which result in noise. As the toroidal propeller has both greater surface area and is more 'regular', it results in less cavitation - hence, producing more noise.
I'm sure there's a more precise term but, essentially, cavitation is turbulence. Turbulent air is 'more solid' than non-turbulent air, providing more resistance against the thrust created by the conventional propeller; as the toroidal propeller produces less cavitation (and less turbulence), there's less resistance pushing back against the thrust it provides.
During flight, the plane is constantly moving through air which has yet to be affected by the propeller. Hence, the turbulence/cavitation caused by the propeller is less a factor in the amount of force imparted by the propeller's thrust pushing against it.
I'm sure there's a more proper explanation for this phenomenon, but I haven't studied this field enough to know what it is.
By increasing the number of blades, you must reduce the diameter of the propeller. Each more blade is 1" less in diameter. Lower thrust may be caused by too much load on the engine, which results in lower revolutions. I'm waiting for further tests;)
That makes sense
It's not about which is better, it's about what application would be good for them. They'd be perfect for Paramotor Planes, not much power is necessary, but being quiet would be a huge improvement for them.
It looks like the regular propeller is made from a different material than the propellers. I would recommend printing a regular propeller with the same material, to test the toroidal prints against. This will ensure consistency in your testing
I think the toroidal propeller was designed for maximum efficiency in the mid-range of engine rpm. Instead of testing thrust at the highest RPM, maybe test thrust at lower RPM to see if the toroidal propeller generates more thrust with less power. Air also has different fluid dynamics than air. I believe the point of the toroidal propeller is to minimize cavitation compared to a regular propeller, and that affect may not be as influential to noise and engine efficiency in air as it is in water. You put in a lot of work with this experiment. I'd love to see more experiments with these same propellers!
If you match the thrust the sound goes back to normal.
They aren't quieter. They just have their noise more spread out over more frequencies that are less audible to humans, there quieter.
Somewhat like the tread on tires going from blocky to variable spacing and angular shapes to spread out the impact and therefore spread out the noise.
I've seen this test so many times, and they always use 3d printers for the toroidal propellers, which completely skews the results. Regular propellers are thinner and lighter while also being stronger, they're weight balanced, have proper air foils, and have a smooth surface. 3d printed propellers are almost never perfectly weight balanced, which creates a lot of vibrations and motor resistance on top of the extra weight and thickness. They also often don't have proper air foils, but just flat, uneven surfaces with right angle edges as yours did, which creates a lot of vortexing and wind resistance.
The toroidal propellors also remove the higher pitch sounds from the propellers, which makes us percieve them as being even quieter even without a huge change in decibel level.
I think your toroidal propellers were partially stalling out due to the air not really having the linear flow.
Trying them out in the open air, I would see which one was faster.
I have heard of racing and fighter planes having a prop stall.
I’d like to know how fast they really go.
You should compare the motor current as well. Efficiency is also very important thing.
I believe that flower-type propellers were rotating slower, so this is why they were less noise and less throsty.
It seems like the tips are the problem, not enough "bite" and directed thrust. The area where the blade folds back over itself, at the tip, needs a more aggressive shape.
If you look out from the center along the blade the end should be grabbing the air on the outside and redirecting it backwards. Regular blade tips are thin for less resistance. The toro-blade has material there. Is it dead weight or another useful surface?
Nice test! I think you should also 3D print the regular propeller from the same material you made the toroidal propellers, perhaps the finish has an effect on the final results.
Change the pitch angle of the blades. The leading blade at a less of a pitch than the following blade.
The leading of the loop is pushing the air out of the way so the following edge has less volume available within the blade space.
If you have the end of each loop also pitched in a way to focus the air on the outside of the loop into the inner part of the loop.
Drag comes in many forms.
Just as wing shapes create different amounts of drag, a prop with more surface area will create more drag, causing the engine (or motor, if electric) to work harder.
You will likely notice reduced run time from your battery if it is electric.
This is why real GA aircraft stick with the simple dual blade prop design.
A fixed pitch propeller works optimally in a given airflow speed. This thrust comparison test shows only the zero airflow speed results without RPM regulation of the motor, so the different prop blade drag values also gave different RPMs. You cannot really compare these in this way.
Thing about decibels. Each one is an EXPONENTIAL increase. Meaning going from 100 dB to 101dB is actually 100% louder.
Food for thought when there's a 6dB decrease.
Would be interesting to check the Ratio Thrust/Amps. If they produce 25% less thrust, but 30% less power usage, they'd still be better, and just upgrade the motor to compensate for the loss.
From just looking at the video, it appears the pitch is more aggressive on the 3d printed ones AND the edges that cut through the air aren’t as sharp as the two blade. If you were to experiment with those two features, you could beat the regular propeller and be even quieter.
They are likely weaker due to blade deflection because the material isn't as stiff.
Can you try weight normalizing them?
The turoidal ones can have thinner blades because they have stronger structures.
I'm wondering if the heavier 3D printed blades had an impact on thrust.
The problem here is that the outer tips/edge of the toriodial propellers create unstable turbulent airflow at a far greater rate than a traditional propeller. That's where you are loosing your power and is the reason we do not use them on airplanes.
This is true in full size aircraft as well. As an example, Beech King Airs with the standard 3 bladed props are louder inside and out, but exhibit higher top speeds. Whereas those fitted with 5 blade upgrades from a company like Raisbeck tend to have better climb performance and a quieter ride in the cabin but also suffer a slight cruise speed penalty.
the sound is not that quieter, they make a lower frequency off notice, but they are actually made for drones, that rund way faster..
The Blade cross section on the toroidal props are not as "wing-like" as the stock prop. This would limit or eliminate the "Bernoulli Effect" allowing for more thrust from the standard prop. This is vastly more important in water than air. Plus, having MORE surface area to generate thrust, the Tordial props should, in fact, be more powerful.
My advice you should have compared also is three blade propeller with and without the toroidal version.
Because more blades request more torque. And since you are limited with your engine. The maximum revolutions are lower with higher blade numbers.
Você precisa modificar o ângulo de ataque do perfil toroidal a fim de tornar ele mais eficiente para a velocidade de rotação que você deseja.
Don't forget that the decibel scale represents a doubling every three decibels because it's logarithmic so the five blade toroidal was a factor of four quieter than the standard propeller.
I suspect that some of this absence of noise correlates with an absence of thrust created
should have testing thrust normalized to noise, since that's the metric you're interested in. Are they quieter? Are they weaker? For the same kg of thrust, do you get less noise?
My dad changed from 4 blade propellers to 5 blades on his boat, the F/V SAGA. He ended up needing more powerful main engines to turn them efficiently. I wonder if this could be a similar situation.
As a person trained in basic aerodynamics and with real aircraft maintenance experience I can say that propellers are specically formed in a way to get as much "bite" on the air as possible as pulls t the plane through the air while minimizing drag. It seems that the new propellers have a lower pull and higher parasitic drag coiefficients. Still an interesting idea though.
The regular propeller is twice as loud as the 5 blade propeller. For those wondering
Anyone in the hobby knows thrust is largely decided by the pitch of the propeller. Since you should be using a brushless motor, RPMs will be constant, so refining the pitch of the rotors till they match either the thrust, or the power draw and then testing would be a true test.
Did you actually designed and built them correctly tho?
A lot of RUclipsrs are building toroidal props because one marine company sells them and a univeristy made a project based on toroidal propellers, but those youtubers did not do the same amount R&D as the marine company and university. You can't expect the results would be the same.
less thrust more efficient ? use less fuel ?
6dB doesnt sound like a huge reduction, but it's a logarithmic scale. Every 3db is effectively double the air pressure. Air pressure and percieved volume dont line up exactly but this is still almost 1/3 quieter.
Could you show a thrust/rpm graph? I am interested in knowing the maximum rotation speed and the minimum that sustains the aircraft. Thanks.
You should consider using a spectogram to view the entire frequency range.
maybe those new blade designs have a better efficiency long term, with "fuel" consumption and such, but as several have pointed out either make a control copy of the original 1 blade propellor, so it's mass with the same material can be measured against the toroidals, or smooth and slick the new blades to match the original one. My observation anyways.
Did you smooth the surface, after printing them. A rough surface will make more noise.
Try 3d print your regular propeller from the same material. For more acurraci. And plane may need some tuning too I gues. It is optimalized for this regular type
In terms of noise level, I notice that the edges of the toroid propeller ribbons are sharply squared-off. If possible, it might make sense to make those edges smoothly curved.
I just bought that Carbon Cub. And um. I crashed it on my first flight. I don't have that much free space to fly and the starboard wheel fell of during take off... Another thing was that I didn't realize how much the airplane relied on thrust. It doesn't seem to glide as well as I hoped it to.
Adjust the pitch of your toroidal, and tune for the desired thrust. Think of a constant speed prop - you need “Fine” pitch for take off, and once airborne you back off the pitch for cruising speed. As your little toy doesn’t have adjustable pitch, you have to set it up on the ground.
Have you compared with 2 toroidal bladed propellers? Based on your 3 and 5-bladed toroidals data, the 2-bladed toroidal propellers may be equivalent with the regular 2-bladed propeller.
Try the standard prop but with 3 blades and/or 5 blades and run the same two tests please. I think you’ll see better results.
FYI -6db is equal to -4 times than the original
The 3 blade prop is actually 6 blades and the 5 blade is 10. You should try this with 2 (4) blades and work on the profile a bit.
The reason they are better is because in water they avoid making vacuum bubbles. This isn't an issue in the air (or maybe at some extreme spin it is?! who knows??)
So out of water there is no reason to think they'd be better. In water however they very much are....the issue is the production cost is much higher at the moment.
I really enjoy kinda noisy props honestly. Just sounds cool.
You might have too much pitch on the toroidal prop for the winding or kv of the motor which would reduce its efficiency and ability to produce thrust.
Also worth comparing the load value. I imagine that for the same amount of thrust the toroidal props are using less watts. Thats how they should be