More fun was watching them make the old Alnico magnets where they poured liquid metal into a mold with a "chill" at one end and had an electromagnet wrapped around it. Pretty intense heat with the fun of molten steel.
I especially enjoyed the little rant at the end, because so often people avoid giving opinions because everybody should be encouraged to give their own opinion as if we are all equal in the conversation (we aren't). But I push back against this idea. Some people are experts and I want those experts to give opinions because I will learn from them. We need more rants from experts. Cause then we will learn what things are important or not. Otherwise people will be wanting smooth magnets cause some company produced them instead of because they are good or bad. So keep that going please!
I'm almost sure the difference in shape in those magnets cause differences in the format of the magnetic field and this would explain the big difference in torque despite the small difference in peak field strength.
Great details. One possible justification of the smoothness claim is reduced cogging. Cogging contributes to the noise of the motor, so dba figures would be interesting. With the bonded magnet, there is an opportunity to create a sinusoidal change in magnetic field strength and i believe this can be exploited to reduce the cogging.
i just had to comment to say that after watching your previous motor testing videos, i decided to grab a set of the WASP motors. holy wow, they are NO joke. best motors i'll ever own. never would have gotten them without seeing your testing results, so thanks a ton!
Interesting video showing the difference in rpm, thrust, and explaining how and why the difference between the two magnet types. You did an excellent job talking about the motor types.
Amazing video as always! One small remark, 6:45 we used to say "Centigrade" in the past but now it's considered deprecated. Proper way to say is degrees Celsius.
WOW! Bloody excellent video mate! That was concise and detailed. For guys like me this was gold. I'm getting pretty tired of you tubers googling a subject and trying to explain something they actually have no idea about.
I had the feeling that I was watching a Minecraft Gregtech tutorial when the process explanation started, lol. Thank you very much, it was super interesting!
Yeehaw!! I seen a couple science channels cover these "printed" style magnets. Really cool that they're incorporating them into New Motors. On a side note, newbeedrone make some of the best 702 Motors I've flown.
I get it on the "smoothness" issue. This matters for inexperienced drone pilots. If it doesn't respond to mistakes as quickly, it certainly seems much smoother.
The "smooth" they are talking about is TORQUE smoothness. Torque "unsmoothness" comes from magnetic cogging, as the magnets move closer & farther away from the iron slots in the stator. Weaker magnets DO reduce cogging torque by the SQUARE of the reduction (& as you say, reduces motor efficiency by the same factor). Low cogging torque is important for motors that operate at low RPMs or those that cross through zero RPM (such as in helicopter tail rotor motors). There is a way to reduce cogging torque with less affect on motor efficiency: SKEW THE STATOR STACK. This is routinely done on other motor designs, especially where noise is a consideration, but I have yet to see it done on RC aircraft motors. I wanted to use an aircraft motor as a generator in a turbogenerator for an 1/8th scale steam engine (to make power to run the lights, as was done in the prototype.) The problem is that the cogging torque of the aircraft motor is so high that the turbine can't start it without using 10 times the normal steam flow. This is bad enough, but made worse by the poor performance of turbines when scaled down. For a few watts of electrical output, the turbine ended up consuming more steam than required to move a 600lb engine & its train! What's odd is that the smaller the aircraft motor is, the larger the cogging torque it has.
Very nice. Another factor not covered is amps per pound of thrust. This determines your flight time. A lower magnetic field motor will give more kv's but the number of amps it is pulling is proportionally higher, maybe "more proportionally" than what is practical! Just how big a battery can you carry around!
What I'd be interested in is the cogging of the motors and how the EMF looks on a scope if you just drive the motor with a drill. I would expect the molded magnet to have a much smoother and better distributed field.
The metal the stator is made from makes a difference in efficiency. The high end racing motors used to use cobalt in the stator plates. Its much more expensive though.
I would love to see temperature tests of motors. I'm sure different motors can disipate different amount of heat and therefore we can push them a little harder
Thats more the manufacturers cheaping out on their epoxy they use for bonding the magnets, likely a cost cutting measurse to save them a few pennies insead of spending a bit more for a stronger/better quality epoxy that has a higher thermal limit
Fantastic testing and explanation, Chris! Thanks a bunch!!! 😃 I've read about a discovery the other day, that has the potential to change our motors in the future. It's a long story, but they've found a different mix of iron and nickel, almost 50% of each (if I'm remembering it correctly), in a meteorite that could be used to create strong magnets like what we use today. And now they finally replicated it on a lab. So... Who knows. Let's see what happens. 😊 Anyway, stay safe there with your family! 🖖😊
Wow, it reminds me of the 50% nickel/titanium shape memory alloy. I wonder if mixing 50% nickel with any other metals does anything interesting. Another candidate for rare-earth-free magnets I've heard of is iron nitride.
The o-ring isn't always a good thing from the standpoint of proper bearing loading. You don't want your bearings in compression. If you are worried about bearings in a crash, I just think you have more prominent sources of bearing failure from not being properly loaded in the first place. I would be more worried about over-tightening bell screws when the tolerance stack-up isn't quite perfect, which could cause the inner race of the top bearing to be compressed down and the bottom bearing to be compressed up without a properly toleranced bearing spacer between them. That being said crashing is a quick dynamic event while improper bearing loading is a longer timescale fatigue question. I understand this is a point of controversy when it is an argument about what is likely to fail first and to what degree failure occurs when the event happens. It is a bit of the "what-if game." The o-ring wouldn't have the advantaged effect without improper loading of the bearing if a bearing spacer was added to the design.
I don't think the compression of a flexible rubber oring is the type of load they mean but they could always add a shim between the upper and lower bearings inner races. That said I usually assume the o ring is used to account for any lack of precision in the shaft length, not to prevent impact damage on the top radial bearing.
@@ChrisHarmon1 I agree with you, with one exception; why do you think that the top bearing will be the only bearing to see damage? I argue that in a crash the bearing farthest from the torque lever of the prop/bell top combo will see more damage.
I can’t imagine that the partial compression of an o-ring would come anywhere close to exceeding the axial load limits for a decent-quality ball bearing. But it would certainly be prudent to make certain - perhaps CR could examine them for a MPN?
Thank you Eng. Chris Rosser , I really enjoyed all info you have presented ... Are you also specialist in stepper motors and DC brushless motors used in industry ?
I wonder if there will be more experiments in this magnet configuration. Like 4 quadrant bell or mixed config or something like that. Very interesting though.
Would you consider doing tests like this for the micro motors we use in whoops? 0702, 0802, 1002 and 1102s are all available in all sorts of flavors, but we have no empirical data on what motors are good or inefficient. I am looking to make a small thrust stand to test some of the motors I have but I don't know i could produce the same detailed results as you have.
Nice work. Is there a weight delta between the two bell designs? - Also a noise test would be educational. Certainly the quad noise will be dominated by the prop. Noise of the pure motor should tell whether there is a bit of truth into the smooth claim.
I think the smooth makes sense in the way manufacturers want to use it. Almost like slower rates to achieve a smoother looking flight. Higher rates without proper control will seem more jerky. The high response might give you the exact flight results for a good pilot, but the slower response will make a new pilot seem smoother. I noticed that when I wanted I got video of my flying chasing trucks just how much I’m moving the sticks, slower response could could be damping the jerks slower to be perceived less.
The main symptom of low torque and poor motor responsiveness is bad propwash and in the worst case motor desyncs. Not things that are generally assoicated with smooth flying quads. Low rates and lots of RCsmoothing give a smooth flight experience without compromising propwash handling so that's where I would start with smoothness. There seems to be a misconception that its better to do things with hardware rather than software but that's incorrect in this case. You need a quad that responds fast to propwash and slow to stick inputs, that can only be done in the FC software.
@@ChrisRosserit's been tried and tested though, like how bubbyfpv made a 2205 motor for full 5 inch for smoothness. He wouldn't have made it if he hadn't tested it and found it to be smoother
Clever design, however durability maybe an issue, I can see the one-piece magnet cracking after a hard crash? Separated magnets have a gap and are less likely to break.
Is the neo magnet a N52 or N48? I know N52 is most common for maximum torque (power) but people like ethix use N48 on some motors for smoother motors\less noise along with a slightly larger gap to stator, how would the ring compare to a N48?
Maybe it is SMOOV but is it JUCEE? 😆 Thanks for bringing science and facts to the feels-fight! 2.5mm flat head screw though, yikes, the 3mm can be tough enough to get out.
I think smoothness discussion could be like low torque on flatter motors discussion ( with equal volume of the stator ) Science mode off I think there is truth in each one, there are so much variables in builds that can introduce much more in the equation and you could find a less strong straight magnet ( instead of curved ) that got more “rounded” or “manageable” response …my2cents
What if the bell and shaft is made of carbon fiber or kevlar or air grade aluminum? Weight reduction on all the moving parts would improve the spin all around, plus increase the response with less resistance. It should use less current in the end. Kinda like changing the fly wheel on a car.
The argument that they are smooth falls flat when something magnetic gets into the motor, the gaps give it somewhere to go, out of the path of movement. Smooth surface with nowhere to go becomes a sander belt. Maybe they should look at a 1950's motor engineers handbook where those gaps are explained. The argument back then was minimal gap size as well, but since they explained the science pretty well, that trend was abandoned.
Since the magnetic field strength decreased the rpm of the motor should be increased right ? Resulting drop in torque. Beacuse the FPV motor focuse on rpm reather then tourqe that won't be problem
I think the sharp edge might actually be a sort of bumper... deforming where it's thin and not affecting the more important structure beneath. little chunks taken out... but no real damage... but it's extra weight right?
it could be but a deformed edge will probably mess up with the balance of motor. The o ring would probably do better as an energy absorbing part than the edge
@@im_ricebowl one of my motors lost 1/3rd of a magnet. Took the props off, did a noise vs throttle plot and it's fine, all the noise was sub 200hz. I wouldn't worry about a dent personally.
Great review Chris. Very well explained. Curious how did the weight of the two motor bells compare? (seeing 33g vs. 33.6g for motor with wire in specs) Would expect weight to have some effect on angular momentum if significantly different, but this doesn't appear to be the case. Torque from the stronger individual magnets does seem to offer an advantage in many aspects. Agree with your rant, marketing around smoothness, appears to be just that ... marketing. Raw performance is what matters ... high quality elements that are assembled into a well balanced motor design. One thing that would have been interesting to see is a plot of the magnetic field (mT) for each bell. If you could mound the probe and then rotate the bell with a servo (over 180º), it wold be possible to see how the magnetic field change polarity. ie: is it a nice square wave pattern, or a plot with rounded corners? Realize would be time consuming unless had a fixture to help automate data collection. It could also show how wide that magnetic field is, as may not be the full width of a single magnet. (?) An alternative method would be to vacuum seal the motor bells in plastic (freezer bag style), and then use metal filings to show the magnetic fields.
Keep in mind that this motor screw should be tightened with very specific torque, and if you over/under tighten it, it would reduce motor performance. Manufactures do not recommend taking motors apart unless absolutely necessary
Stronger magnets mean fewer turns are need to achieve the target performance. Fewer turns have less resistance so the motor is more efficient. That translates into longer run times. Thats the main benifit of stronger magnets.
So I'm wondering if you could magnetize the ring in a twisted fashion similar to Kabab's split motor video. Also wondering if it could be magnetized in a halbauch array? Twisted halbauch?
i had a discussion about such smoth motors below. what do you think? 1: using smoth motors is ok to avoid vibrations, twitchyness or something like that? 2: using the given things in betaflight and Pidtoolbox to make it smooth, if this is the goal.
I think that a low torque motor won't reduce vibrations. Vibrations are caused by the balance of the motor which is independent of it's torque (and down to manufacturing quality). The flight controller constantly requests rapid changes of motor RPM and if the motor can't do that desyncs occur and the quad falls out of the sky. If you want a smooth flying quad you should use filtering on your sticks in betaflight (RC smoothing) rather than try to slow down how fast the motors can respond. That way you can get smooth stick feel but still good propwash handling and setpoint tracking.
I suspect it’s not the reduction in torque that they’re referring to as smoothness: what they’re probably trying to imply is that the actual torque of the motor varies less over the course of a rotation than it does with other motors. One presumes that this is caused by a combination of a smoother transition between magnet poles and a motor controller that puts a higher emphasis on accurate voltage regulation than on maximum power output. In theory, a smoother application of torque might result in less resonance effects in the prop which could result in less vibration and consequently less noise. Obviously, none of that will be true in practice if the motor is not also finely balanced, nor if it’s used with a square wave driver or other noisy input and the effects it’s trying to mitigate can also be addressed with alternate prop geometry, but if the design theory they’re operating under holds up, you should notice that the whine of a less than stellar motor controller is less noticeable with the bonded magnet than with the sintered one (and to a greater degree than would be explained by the difference in field strength).
Doesn't the polymer itself and the reduced surface area reduce cooling? I'm no expert, but I got the impression excessive heat is't great for magnets in general, neither for polymers. Also, energy used that isn't turned into work is turned into heat, if the cooling is suboptimal it wouldn't be great to also have suboptimal efficiency.
I noticed that you didn't weigh them. What if the bell of the ring magnet version is half of its sintered-magnet counterpart? One of the important factors in these drones/planes is overall weight-to-thrust.
I'm slightly confused though, the bonded magnet is alligned while its curing? or when its first mixed? great video! great explanations, and well edited too, will defnitely check out your other vids
A ring magnet with 14 flux paths. I find it amazing. I guess the next step will be 3D Printing Ring magnets. Rapidia would probably be the company that could make it happen.
Is there a place where we can access to all the test results? I'm trying to decide on a 4s motor and it's very difficult to find good tests as yours. A complete chart of your digital latency tests will be very useful as well.
By adulterating the neodymium with plastic in between the flakes the overall magnetic flux is reduced as is it’s maximum operating temperature. A sintered toroid with an internal halbach organization should be a more ideal ring magnet
Interesting but even seemed gimmicky: Chris Rosser is the reason my Diatone Roma v2 is rolling with Wasp Major 1860kV motors. It was 4S and I swapped motors to go to 6S. I probably could have gotten some cheaper motors and not know the difference but it flies so good on a barely more aggressive than stock Betaflight tune.
i just threw a set on my newest build and they really are THAT good. absolutely love those motors. never would have considered them without seeing his previous videos.
The bonded magnet ring needs to show a cost adantage to offset inherent lower magnetic properties. Otherwise marketing hype. Thanks for the technical review.
The first step is to align the grains of magnet powder in the direction they are most happy to be magnetised in. The second step uses a SUPER powerful magnet to actually magnetise all the grains. The key bit of information is that every grain of magnet powder (due to its microstructure) has a preferred direction to be magnetised in so lining them all up is beneficial.
I move the probe around to find the maximum. Sometimes when the probe is moving you get a spike in reading but when you move slowly its easy to find the maximum field.
The first field sets the preferred magnetisation direction. Only the final field actually magnetises it. The Curie temperature only applies after the final magnetisation. Heating a magnet to above the Curie destroys its magnetism but NOT its preferred magnetisation direction! That persists up to the melting point.
Man, this explanation on how magnets are made was super cool! I love your channel!
More fun was watching them make the old Alnico magnets where they poured liquid metal into a mold with a "chill" at one end and had an electromagnet wrapped around it. Pretty intense heat with the fun of molten steel.
I especially enjoyed the little rant at the end, because so often people avoid giving opinions because everybody should be encouraged to give their own opinion as if we are all equal in the conversation (we aren't). But I push back against this idea. Some people are experts and I want those experts to give opinions because I will learn from them. We need more rants from experts. Cause then we will learn what things are important or not. Otherwise people will be wanting smooth magnets cause some company produced them instead of because they are good or bad. So keep that going please!
I'm almost sure the difference in shape in those magnets cause differences in the format of the magnetic field and this would explain the big difference in torque despite the small difference in peak field strength.
Great details. One possible justification of the smoothness claim is reduced cogging. Cogging contributes to the noise of the motor, so dba figures would be interesting. With the bonded magnet, there is an opportunity to create a sinusoidal change in magnetic field strength and i believe this can be exploited to reduce the cogging.
Combine that with sine wave ESC and it would be very smooth and quiet.
being old af and having flown balsa nitro planes in the 90's its awesome to see new tech like this, very exciting
I was able to follow this all the way and understand. Chris thank you for being in this hobby 🙏
My pleasure!
i just had to comment to say that after watching your previous motor testing videos, i decided to grab a set of the WASP motors. holy wow, they are NO joke. best motors i'll ever own. never would have gotten them without seeing your testing results, so thanks a ton!
Rant at the end was brilliant! Thanks again Chris!
Glad you enjoyed it
Interesting video showing the difference in rpm, thrust, and explaining how and why the difference between the two magnet types.
You did an excellent job talking about the motor types.
Amazing video as always! One small remark, 6:45 we used to say "Centigrade" in the past but now it's considered deprecated. Proper way to say is degrees Celsius.
thanks for the review Chris, we will taking the feedback and work with our factory to make it better.
I love the dive into how the magnets are made. Professor Rosser. Cheers
WOW! Bloody excellent video mate! That was concise and detailed. For guys like me this was gold. I'm getting pretty tired of you tubers googling a subject and trying to explain something they actually have no idea about.
I had the feeling that I was watching a Minecraft Gregtech tutorial when the process explanation started, lol.
Thank you very much, it was super interesting!
Excellent vid! Well done Chris! Thanks for this
Yeehaw!! I seen a couple science channels cover these "printed" style magnets. Really cool that they're incorporating them into New Motors. On a side note, newbeedrone make some of the best 702 Motors I've flown.
I love everything about your videos. Looking forward to the next one!
This was absolutely priceless.
Thank you wholeheartedly.
I get it on the "smoothness" issue.
This matters for inexperienced drone pilots. If it doesn't respond to mistakes as quickly, it certainly seems much smoother.
Unbelievable work my man!! Cheers!
Fascinating stuff Chris! Thanks
The "smooth" they are talking about is TORQUE smoothness. Torque "unsmoothness" comes from magnetic cogging, as the magnets move closer & farther away from the iron slots in the stator. Weaker magnets DO reduce cogging torque by the SQUARE of the reduction (& as you say, reduces motor efficiency by the same factor). Low cogging torque is important for motors that operate at low RPMs or those that cross through zero RPM (such as in helicopter tail rotor motors).
There is a way to reduce cogging torque with less affect on motor efficiency: SKEW THE STATOR STACK. This is routinely done on other motor designs, especially where noise is a consideration, but I have yet to see it done on RC aircraft motors. I wanted to use an aircraft motor as a generator in a turbogenerator for an 1/8th scale steam engine (to make power to run the lights, as was done in the prototype.) The problem is that the cogging torque of the aircraft motor is so high that the turbine can't start it without using 10 times the normal steam flow. This is bad enough, but made worse by the poor performance of turbines when scaled down. For a few watts of electrical output, the turbine ended up consuming more steam than required to move a 600lb engine & its train! What's odd is that the smaller the aircraft motor is, the larger the cogging torque it has.
The best ideea ever on how neodymium magnets are made Thumbs Up for that
Very nice. Another factor not covered is amps per pound of thrust. This determines your flight time. A lower magnetic field motor will give more kv's but the number of amps it is pulling is proportionally higher, maybe "more proportionally" than what is practical! Just how big a battery can you carry around!
As usual perfect lecture about FPV science ;-) This is who must say "And you gonna learn something today" ;-)
Great video! Thank you for doing this!
What I'd be interested in is the cogging of the motors and how the EMF looks on a scope if you just drive the motor with a drill.
I would expect the molded magnet to have a much smoother and better distributed field.
The slot inside the stator isn't for holding glue, it is for alignment on the auto winding machine
That was the most polite rant I have ever heard.
The metal the stator is made from makes a difference in efficiency. The high end racing motors used to use cobalt in the stator plates. Its much more expensive though.
The MT should be mT (milli vs Mega). Thanks for sharing.
Great point! I think that caption is in all caps. At least it's correct on the meter 🤣
I would love to see temperature tests of motors. I'm sure different motors can disipate different amount of heat and therefore we can push them a little harder
i love your videos i like to learn new things and you are good at explaining things thanks for the how magnets are made info
Wow the magnet manufacturing process is interesting.
Thanks for an informative but understandable vid bro thanks for the diagrams
This is very interesting. The main problems I had with motors were the magnets detaching.
These might be more robust. Neat!!
Thats more the manufacturers cheaping out on their epoxy they use for bonding the magnets, likely a cost cutting measurse to save them a few pennies insead of spending a bit more for a stronger/better quality epoxy that has a higher thermal limit
Wow! Thanks to your video now I will make a more informed purchased. ❤
I believe the "sharp edge" would be for cooling when air is crammed through it by the core of the propeller.
Fantastic testing and explanation, Chris! Thanks a bunch!!! 😃
I've read about a discovery the other day, that has the potential to change our motors in the future.
It's a long story, but they've found a different mix of iron and nickel, almost 50% of each (if I'm remembering it correctly), in a meteorite that could be used to create strong magnets like what we use today. And now they finally replicated it on a lab.
So... Who knows. Let's see what happens. 😊
Anyway, stay safe there with your family! 🖖😊
Very cool! Neodymium is pretty rare and fragile so strong magnets without it would be great.
@ChrisRosser I just sent some links about it to Joshua and ItsBlunty, for the news. 😊
Wow, it reminds me of the 50% nickel/titanium shape memory alloy. I wonder if mixing 50% nickel with any other metals does anything interesting.
Another candidate for rare-earth-free magnets I've heard of is iron nitride.
@@dekutree64 Yeah, there are lots of new options being studied... I hope we can see some of them in the market soon! 😃
@@ChrisRosser Have you followed the development of brushless motors in slot cars ?
Use a solder iron not a heat gun on the thread locked bolt, love these reviews would love to see larger like 2808 size.
The o-ring isn't always a good thing from the standpoint of proper bearing loading. You don't want your bearings in compression. If you are worried about bearings in a crash, I just think you have more prominent sources of bearing failure from not being properly loaded in the first place. I would be more worried about over-tightening bell screws when the tolerance stack-up isn't quite perfect, which could cause the inner race of the top bearing to be compressed down and the bottom bearing to be compressed up without a properly toleranced bearing spacer between them. That being said crashing is a quick dynamic event while improper bearing loading is a longer timescale fatigue question. I understand this is a point of controversy when it is an argument about what is likely to fail first and to what degree failure occurs when the event happens. It is a bit of the "what-if game." The o-ring wouldn't have the advantaged effect without improper loading of the bearing if a bearing spacer was added to the design.
I don't think the compression of a flexible rubber oring is the type of load they mean but they could always add a shim between the upper and lower bearings inner races. That said I usually assume the o ring is used to account for any lack of precision in the shaft length, not to prevent impact damage on the top radial bearing.
@@ChrisHarmon1 I agree with you, with one exception; why do you think that the top bearing will be the only bearing to see damage? I argue that in a crash the bearing farthest from the torque lever of the prop/bell top combo will see more damage.
I can’t imagine that the partial compression of an o-ring would come anywhere close to exceeding the axial load limits for a decent-quality ball bearing. But it would certainly be prudent to make certain - perhaps CR could examine them for a MPN?
@@modquad18 it doesn’t take much force to pin the inner race to one side of the balls.
That's really one hell of a video
Well said (and tested) 🤘
Wonderful practical confirmation that electric motor's torque constant (N*m/amp) is inverse of motor's Kv.
Maybe the purpose for the O ring is so the dust doesnt get into the bearings
I would think you would want to test it with the stator swapped both ways.
Thank you Eng. Chris Rosser , I really enjoyed all info you have presented ... Are you also specialist in stepper motors and DC brushless motors used in industry ?
the _peak_ is higher, but that is not enough to conclude it is better. The shape of the curve is also important.
Thank u for this info. I am curious about the any noise difference comparison
I wonder if there will be more experiments in this magnet configuration. Like 4 quadrant bell or mixed config or something like that. Very interesting though.
Would you consider doing tests like this for the micro motors we use in whoops? 0702, 0802, 1002 and 1102s are all available in all sorts of flavors, but we have no empirical data on what motors are good or inefficient. I am looking to make a small thrust stand to test some of the motors I have but I don't know i could produce the same detailed results as you have.
Well the title caught me with the No Magnets? Then proceeded to explain about the magnets used and best part how they are made.
Nice work. Is there a weight delta between the two bell designs? - Also a noise test would be educational. Certainly the quad noise will be dominated by the prop. Noise of the pure motor should tell whether there is a bit of truth into the smooth claim.
I think the smooth makes sense in the way manufacturers want to use it. Almost like slower rates to achieve a smoother looking flight. Higher rates without proper control will seem more jerky. The high response might give you the exact flight results for a good pilot, but the slower response will make a new pilot seem smoother. I noticed that when I wanted I got video of my flying chasing trucks just how much I’m moving the sticks, slower response could could be damping the jerks slower to be perceived less.
The main symptom of low torque and poor motor responsiveness is bad propwash and in the worst case motor desyncs. Not things that are generally assoicated with smooth flying quads. Low rates and lots of RCsmoothing give a smooth flight experience without compromising propwash handling so that's where I would start with smoothness. There seems to be a misconception that its better to do things with hardware rather than software but that's incorrect in this case. You need a quad that responds fast to propwash and slow to stick inputs, that can only be done in the FC software.
@@ChrisRosserit's been tried and tested though, like how bubbyfpv made a 2205 motor for full 5 inch for smoothness. He wouldn't have made it if he hadn't tested it and found it to be smoother
There may be 5% less "magnet" per magnet
but the segmented magnet has _gaps_
so in total, the single magnet may have more magnet in it?
Clever design, however durability maybe an issue, I can see the one-piece magnet cracking after a hard crash? Separated magnets have a gap and are less likely to break.
I have these on eight quads and all run smoothly and give me a lot of flight time, whether 4s or 6s.
Brilliant explanations.
Is the neo magnet a N52 or N48? I know N52 is most common for maximum torque (power) but people like ethix use N48 on some motors for smoother motors\less noise along with a slightly larger gap to stator, how would the ring compare to a N48?
Maybe it is SMOOV but is it JUCEE? 😆 Thanks for bringing science and facts to the feels-fight! 2.5mm flat head screw though, yikes, the 3mm can be tough enough to get out.
Asking the real questions Cap!
Seems pretty consistent with the NBD product line in general.
I think smoothness discussion could be like low torque on flatter motors discussion ( with equal volume of the stator ) Science mode off I think there is truth in each one, there are so much variables in builds that can introduce much more in the equation and you could find a less strong straight magnet ( instead of curved ) that got more “rounded” or “manageable” response …my2cents
will holding a soddering iron against the screw head loosen the Loctite? Thanks.
Any chance the reason there is no o-ring is because those are magnets at the top there and will resist the motor in a similar way an oring would?
What is the test stand that you use? Would like to know more about the torque test? Where can i read about it?
What if the bell and shaft is made of carbon fiber or kevlar or air grade aluminum? Weight reduction on all the moving parts would improve the spin all around, plus increase the response with less resistance. It should use less current in the end. Kinda like changing the fly wheel on a car.
Plus it would make it lighter. Eventually resulting in much faster response and longer flight time. In my head lol
Fascinating information.
The argument that they are smooth falls flat when something magnetic gets into the motor, the gaps give it somewhere to go, out of the path of movement. Smooth surface with nowhere to go becomes a sander belt. Maybe they should look at a 1950's motor engineers handbook where those gaps are explained. The argument back then was minimal gap size as well, but since they explained the science pretty well, that trend was abandoned.
Enjoyed! But I didn't see motor weight. Couldn't a motor use extra turns, bigger/heavier magnets etc. to win this competition?
Since the magnetic field strength decreased the rpm of the motor should be increased right ? Resulting drop in torque. Beacuse the FPV motor focuse on rpm reather then tourqe that won't be problem
I think the sharp edge might actually be a sort of bumper... deforming where it's thin and not affecting the more important structure beneath. little chunks taken out... but no real damage...
but it's extra weight right?
it could be but a deformed edge will probably mess up with the balance of motor. The o ring would probably do better as an energy absorbing part than the edge
@@im_ricebowl one of my motors lost 1/3rd of a magnet. Took the props off, did a noise vs throttle plot and it's fine, all the noise was sub 200hz. I wouldn't worry about a dent personally.
I did not see the NBD flow motors on your motor data list on your site.
I forgot to add them but they should be there now. Thanks for the message!
Great review Chris. Very well explained.
Curious how did the weight of the two motor bells compare? (seeing 33g vs. 33.6g for motor with wire in specs) Would expect weight to have some effect on angular momentum if significantly different, but this doesn't appear to be the case. Torque from the stronger individual magnets does seem to offer an advantage in many aspects.
Agree with your rant, marketing around smoothness, appears to be just that ... marketing. Raw performance is what matters ... high quality elements that are assembled into a well balanced motor design.
One thing that would have been interesting to see is a plot of the magnetic field (mT) for each bell. If you could mound the probe and then rotate the bell with a servo (over 180º), it wold be possible to see how the magnetic field change polarity. ie: is it a nice square wave pattern, or a plot with rounded corners? Realize would be time consuming unless had a fixture to help automate data collection. It could also show how wide that magnetic field is, as may not be the full width of a single magnet. (?)
An alternative method would be to vacuum seal the motor bells in plastic (freezer bag style), and then use metal filings to show the magnetic fields.
Keep in mind that this motor screw should be tightened with very specific torque, and if you over/under tighten it, it would reduce motor performance. Manufactures do not recommend taking motors apart unless absolutely necessary
Stronger magnets mean fewer turns are need to achieve the target performance. Fewer turns have less resistance so the motor is more efficient. That translates into longer run times. Thats the main benifit of stronger magnets.
So I'm wondering if you could magnetize the ring in a twisted fashion similar to Kabab's split motor video.
Also wondering if it could be magnetized in a halbauch array?
Twisted halbauch?
Yes a twsited magnetisation is possible. I'm not sure about a Halbach array. The flux ring achieves the same effect so I guess it is not needed.
@@ChrisRosser ooo. Flux ring? I'm not familiar.
@@Digit-Did-It metal around the outside of a motor
i had a discussion about such smoth motors below. what do you think? 1: using smoth motors is ok to avoid vibrations, twitchyness or something like that? 2: using the given things in betaflight and Pidtoolbox to make it smooth, if this is the goal.
I think that a low torque motor won't reduce vibrations. Vibrations are caused by the balance of the motor which is independent of it's torque (and down to manufacturing quality). The flight controller constantly requests rapid changes of motor RPM and if the motor can't do that desyncs occur and the quad falls out of the sky.
If you want a smooth flying quad you should use filtering on your sticks in betaflight (RC smoothing) rather than try to slow down how fast the motors can respond. That way you can get smooth stick feel but still good propwash handling and setpoint tracking.
I would expect a less-torquey motor to drain the battery faster too, as the controller will have to work harder - resulting in reduced flight times.
I suspect it’s not the reduction in torque that they’re referring to as smoothness: what they’re probably trying to imply is that the actual torque of the motor varies less over the course of a rotation than it does with other motors. One presumes that this is caused by a combination of a smoother transition between magnet poles and a motor controller that puts a higher emphasis on accurate voltage regulation than on maximum power output. In theory, a smoother application of torque might result in less resonance effects in the prop which could result in less vibration and consequently less noise. Obviously, none of that will be true in practice if the motor is not also finely balanced, nor if it’s used with a square wave driver or other noisy input and the effects it’s trying to mitigate can also be addressed with alternate prop geometry, but if the design theory they’re operating under holds up, you should notice that the whine of a less than stellar motor controller is less noticeable with the bonded magnet than with the sintered one (and to a greater degree than would be explained by the difference in field strength).
I noticed that the bonded magnet appears thinner than the sintered magnet. Might this have contributed to the lesser field strength?
Is there a cost advantage to the bonded magnet motor?
Doesn't the polymer itself and the reduced surface area reduce cooling? I'm no expert, but I got the impression excessive heat is't great for magnets in general, neither for polymers. Also, energy used that isn't turned into work is turned into heat, if the cooling is suboptimal it wouldn't be great to also have suboptimal efficiency.
I noticed that you didn't weigh them. What if the bell of the ring magnet version is half of its sintered-magnet counterpart? One of the important factors in these drones/planes is overall weight-to-thrust.
I did but clearly forgot to mention: The SMOOV is 34.3g and the FLOW is 35.1g (with 5" wires)
great video.
Great video
Surprised they even made the bonded magnet idea work properly...
How well was the motors balanced?
I have a sudden desire to hear Gordan Ramsay narrate a video about cooking up a neodymium magnet.
I'm slightly confused though, the bonded magnet is alligned while its curing? or when its first mixed?
great video! great explanations, and well edited too, will defnitely check out your other vids
Very informative.
A ring magnet with 14 flux paths.
I find it amazing.
I guess the next step will be 3D Printing Ring magnets.
Rapidia would probably be the company that could make it happen.
Would tunning the ESC to a new motor help?
no.
Is there a place where we can access to all the test results? I'm trying to decide on a 4s motor and it's very difficult to find good tests as yours. A complete chart of your digital latency tests will be very useful as well.
??? He mentions it in the video
Yep all available on the website aos-rc.com with full data available on the discord in the patreon section.
By adulterating the neodymium with plastic in between the flakes the overall magnetic flux is reduced as is it’s maximum operating temperature. A sintered toroid with an internal halbach organization should be a more ideal ring magnet
Interesting but even seemed gimmicky: Chris Rosser is the reason my Diatone Roma v2 is rolling with Wasp Major 1860kV motors. It was 4S and I swapped motors to go to 6S. I probably could have gotten some cheaper motors and not know the difference but it flies so good on a barely more aggressive than stock Betaflight tune.
i just threw a set on my newest build and they really are THAT good. absolutely love those motors. never would have considered them without seeing his previous videos.
The bonded magnet ring needs to show a cost adantage to offset inherent lower magnetic properties. Otherwise marketing hype. Thanks for the technical review.
I loved your explanation of magnet fabrication. However,it looks like you had two magnetization steps, and it was not clear how or why?
The first step is to align the grains of magnet powder in the direction they are most happy to be magnetised in. The second step uses a SUPER powerful magnet to actually magnetise all the grains. The key bit of information is that every grain of magnet powder (due to its microstructure) has a preferred direction to be magnetised in so lining them all up is beneficial.
Was it possible when you put the probe, it was in between 2 magnets which gave you 430mt?
I move the probe around to find the maximum. Sometimes when the probe is moving you get a spike in reading but when you move slowly its easy to find the maximum field.
Very rich in tecnical content.
Could smooth mean it has less vibration?
Sorry, how is 1100 degrees not way above the Curie temperature for these things? Or why is compactification done in a magnetic field again?
The first field sets the preferred magnetisation direction. Only the final field actually magnetises it. The Curie temperature only applies after the final magnetisation. Heating a magnet to above the Curie destroys its magnetism but NOT its preferred magnetisation direction! That persists up to the melting point.
I dont think iron has a preferred direction of magnetization, for example. Does this have to do with the crystal structure of this alloy?