CORRECTIONS. 25 / 5 is 5. Which gives a 5:1 ratio. 25 / 5 is not 1. I hate talking about math without a script. I accidentally put a 5 in as the 2104's height. That motor is only about 10% larger than a 2004, not 37%. Also, 2104 is a wider motor than a 2004, not taller. I'm not gonna take the video down. Just apologize for getting in a rush and sloppy there at the end.
Hey Joshua, your chapter title and Roogi's site both state the 21mm motor is a 2104, but you put 5 for the height in the cylinder volume calculator for that motor. Using the correct 4mm stator height, the difference is only 10% (not 37%).
@@TweakRacer I think I got a little carried away there at the end I was so excited to show off the technique I got sloppy. 21 is also not a taller motor, it's a wider motor. Sheesh.
@@JoshuaBardwell Totally get it. You are one of the very few who make corrections and make sure the most accurate info is out there. Thanks for all your hard work. You rock JB!
The green are transition zones between sizes on the chart. I've got a new pickle for you to decipher too. Check out the metrics of the craft in my latest video.
When I started flying 1806 motors were the go to for 5” quads and quads were heavy back then. I think it was Evan who made a video a few months back flying Brother Hobby1806 motors on a lightweight race quad and they did really well. Anyhow, the bigger and bigger trend is getting out of hand. Cheers.
If I hadn't already joined your Patreon, this video would have pushed me over the edge. Thanks for the great video JB. I'm off to watch the other motor videos you suggested.
There toon of things you can do while design a feeling's motor. Is all about the preferences and the way you want your curve kick in. Another great video!
Thanks for all you do. I am thinking of building a 3.5 in quad and didn't know what size motor I should use. Watching this video helped me figure that out. So Thanks.and keep doing what you do. Keep ripping my little buddy.
I find 2306.5 is a pretty good balance of weight and power. Outside of FPVcycle 25mm 2306.5 in about 1700kv is what I look for to spin a lowish pitch 5.1" prop on a 650-700g auw quad.
Man JB with the finger on the pulse. I know a LOT of people looking at motors like the 2505... But having a quad around 650g or less seems to be a prerequisite.
I run gemfan 5143 props on my 2fiddy. Granted it's not under 250g. With 2203 2800kv on 3s and 20% cut on 4. My 2fiddy is ridiculously fast and agile to. Good video @joshua bardwell.
I run a 2107/2080kv on 6s racing and it does not get overly hot. I pair this motor with an HQ R35. It is very light and is used on a very light quad. Due to the higher kv the r35 have plenty of top end.
Thank you our drone Jesus! Okay, I’m referring to Zoroe’s post. Got an iflight iH3 drone that’s getting an upgrade for a Cricket mini stack and the motors that came with the iH3 are 3300 KV motors but thinking about getting some 2204’s or 2207’s instead. Just need to get the metrics correct for mounting the motors onto the frame.
Long motors (2212+) have been a staple in the wing hobby forever but seems like wide motors are better for cooling so why aren't they used more often? Responsiveness is not important for flying wings.
the moment arm explanation seems backwards to me. is the stator was wheel being turned from the shat I would agree. but the motor is turning from the bell using the moment arm longer giving greater leverage on the drive shaft. I would like to see the test data on all this time to do some digging.
This is exactly why I fly two eachine lal5’s nearly identical apart from one on the stock 2507 motors and my main which has tmotor f60’s which are 2207. When propped well (racerstar and jb hurricanes) you get the best of both worlds
Bardwell you need to create an app to building a better drone for everybody out there all you do is add in all the specifications and you do all the math and tell us if it's good or not good
Very informative, and well-delivered. Are there instances where it makes sense to use more than 1 motor type on a specific frame in order to better optimize the drone for a given purpose? Does anyone do this?
This is a good theory and it does bring together some meaningful comparison specs, however it seems to make sense to me that a wider motor like a 2505 compared to a 2207 would have more leverage to spin the props considering the power is generated further away from center (prop shaft). Thus would be easier to spin the prop creating faster responsiveness, but give up top end rpm speed because of the rotating mass further away from center. Like a figure skater initiates a spin with a wide stance to get the rotation going, then pulls the arms in tight to speed the rotation up. If that makes sense?
Please watch Chris Rosser's video linked in the description to see why that isn't true. In short, for 2 motors of the same volume, a larger diameter motor has a shorter magnet which means it has smaller mating surface between the magnet and the stator. This basically exactly cancels out the additional torque created by the longer lever arm (force generated further from the shaft). That's what I remember but go watch his video for the real scoop.
i totally agree with you. i put a link below to a video about 2406 motors and he share the same view as you too in real life testing. it's not just one person but many people have that same feelings towards wider motors, so there have to be some true to it. if you watched Bob Roogi's videos that came out a few years ago. he shared the same view too. and that's the reason he's made 25mm motors for heavy 5" quads and not 2208 motors. i'm not saying Chris Rosser is not smart or not knowledgeable in the matter. but i'm saying he's not always right about everything. science is there to explain phenomena, not the other way around. ruclips.net/video/yta6HwIV5Ew/видео.html
i have 1106 4500kv and 1404 4500kv motors. i'm going to test them with my 2s 4" setup. why 4" and not 3" ? and why low voltage ? well, overpropped and low voltage is where the true will come out. even if i'm wrong i'll still make a post about it and admitting that i'm wrong. so other people can learn from my mistake.
Heavy freestyle quads, bigger gopros. Wide stator like the FPV Cycle 25mm gives amazing throttle resolution and that magic low end torque that pulls you out of close call dives 😆
I would really like a video which explains what goes wrong on each "inapropriate usage" case scenario. For example, what happens when you use motors with lower kv than what you expect for that battery/propsize/payload. What happens when you do the contrary (for example use a "4s" motor with "6s" with the same prop size), and what are more or less tolerable margins. For example, Im buidling something like the terraplane (high power 3" cinwhoop) but I only have 2306 in 1900 kv. I'm wondering what would happen if use them. Props will spin slower than needed I guess. What will happen with the amps? If not, I have 1408 in 3500kv (typically though for 3" open prop). What will happen if I use them with 3" ducted hexablades? Will the motors be damaged? What happens with the amps on the esc. As you can see my questions respond to my "experimental" spirit in combination with the conservative one, as I dont want to breake everything... Thank you as always!!!
Lower kv means less thrust and fewer amps, but eventually you don't have enough thrust to fly. Too high kv means hot, overloaded motors and potential desync.
@@JoshuaBardwell Thank you Joshua! I'll may experiment with my 2306 1900kv to see what happens before I get some 2207 2500kv to put in 6s (in the 3" hexa ducted).
Wider motor has more torque. Try free spinning bicicle wheel from the outer ring and than from middle. You will notice it takes less effort to spin wheel from outer diamater than inside diameter. The taller motors with same valume as wider motor will run hotter as it takes more energy to spin same size prop. You must calculate with prop on as the friction is introduced when prop is spinning. Not different than going uphill vs free spin.
In a brushless motor, assuming the volume is the same, a wider motor is also shorter. This means it has smaller magnets with less mating area between the stator and the magnets. You are right that a longer lever arm makes more torque. However there is another factor at play. The torque of a brushless motor is also proportional to the area of the mating surface between the stator and the bell. The numbers work out that these two effects basically exactly cancel out. A wider motor gets more torque from its lever arm but less torque from its short magnets. There are other things that affect the torque of a brushless motor such as copper density in the winding and the design of the stator and the air gap between the stator and the bell, but these are basically all the same for modern quadcopter motors. As a result, the main thing that affects motor torque is volume of the stator. This has been validated with bench testing as well.
For a layman that doesn't want to understand how electric motors really work (winds, poles, size of wire, etc, etc), I would first decide on prop size and battery cell count (voltage), then target a kv rating (range) to match. For example, for a 6S batt on a 7" prop on a mini quad, i'd be between 1200 and 1500 kv. To make that determination, I'd look at the amount of current the motor can handle, the thrust, then size, weight, and reliability, then dive into efficiency by looking at thrust for given props and amperage. The volume of the stator is of little value in the decision making process. In actuality, the bling of the bell, is the most important factor.
I think that in calculating the torque is always missing something that in my opinion is very important. This thing is the arm on which the torque applies. The fulcrum of the torque is actually the rotational center of the motor shaft, and the arm is obviously the the distance of the magnets from it. The greater force that the motor must win is the break of the prop spinning in air. It also applies on the motor shaft. So we got the powering arm and the resisting arm of the torque. Someone should bench it.
I noticed that chart(kabab fpv) doesn't list the lower end motors for micros ie 0802 etc.dont forget us little guys. we don't all want big 4/5" quads.be handy for all the WHOOP racing guys too since that is a Big sport.
2 года назад+1
recommended Prop Diam in inches = Squared Root Of ( Stator Volume (mm³) / Constant (87.5) ) gets you pretty close to ideal prop diam. got it from the graph on Chris Rosser's motors video where he shows the graph but not the formula. i got an excel sheet with some of his formulas and it has become a great starting point for me
Does the constant change between motor sizes? Plugging 2306 (pi*23^2*6)motor into that equation yields about 10.5 inches
2 года назад
@@XBionicMC stator volume should be r×r×π×h so in your case a 2306 motor should be 11.5×11.5×3.14×6 = 2492mm³ So squared root of (2492/87.5) = √28.48 = 5.34" props. This should be a starting idea as noted in Chris videos where he points out that the prop pitch and weight and other factors of various sources could affect your choice. For example I went for a small 2.5" quad and used 1404 motors. In my case stator size= 7×7×3.14×4 = 615mm³. Ideal prop size = √(615/87.5) = 2.65". I was planning to use avant rush props which are known to have an aggressive pitch so I figured it was just about right. And even if a 1404 sounds like a huge size motor for a 2.5" quad, it actually feels amazing and solid. Then I found JB's Transtec Beetle 2.5 HD review and it all made sence. 3.5" props ideal motors are 1506 or similar stator volume, but Chris recommended for his aos3.5 frame some 1404 motors to use the digital video unit and keep the weight under 250 grams, so it's all in your needs.
Torque can not be calculated in cilinder volume of motor as KV coper winding give differential valume. More coper winding generates more torque. If yuu realy want to measure anything than it be the coper volume.
Wonder if heat build up is why I put 8" props on over 7" & lost some top speed 🤔 Under size motors also 7" was on betaflight & better setup. 8" on inav & not set up smoothly. Might lost to oscillations
Could you please compare these T-Motors to Bobs motors? For people outside the US its very hard to get Bobs motors without paying huge shipping costs so this T-Motor might be our only option.
Tmotors have less volume right? Bobs are 2506.2. the difference in volume over 2505.5 is not insignificant. Bobs are also super light. Durability is a major concern on the FPVCycle though.... Bell walls seem thin and don't like concrete
I don't know why I would do these calculations and thinking about stator volume when all the data I really need is already in the datasheet (1:38). Power, torque, efficiency, thrust and and temperature at different RPMs and for different prop sizes - what more could I ask for?
This whole discussion depends on entirely on the assumption that the motors are of equal quality. A motor the looks superior on paper may be hamstrung by poor quality magnets or an oversized airgap.
Let me save everyone some time. 2207 is the perfect freestyle motor for almost every 5" quad. if you have a very heavy quad like 800 to 900 grams then go with a 2208. it's that simple. Well at least if you are in it to have fun with plenty of power. No offence intended Mr Bardwell. This has just been my experience with testing many many quads.
Learned a lot in this one Josh, thks! Been wondering though, as you mentioned the 2 common examples of alternative motors in this vid: what alternative motor could you compare the Brotherhobby 2507 v2 1700kv against? Is there any in that category?
No. Chris Rosser's video explains why. What actually matters is the surface area of the air-gap (the size of the mating surface between the magnets and the stator), multiplied by the radius of the motor. The size of the mating surface determines the force generated by the magnetic field; the radius of the motor is the lever arm length, and force * lever arm = torque. Area of the air gap = 2*pi*r*h Torque arm = r therefore Torque is 2*pi*r^2*h By pure coincidence (or by some underlying principle that is non-obvious) this is the formula for the volume of the stator. For what it's worth, Chris's theory has been validated with experimental testing.
at 5:00 you write that the motor is 2550 but its is in fact 2505 for average flyers we understand what you mean, but for newcomers...that's a big motor!
Joshua... I am puzzled... Volume measured solely on the outer dimensions of the stator... makes me ask, what about the inner dimensions of the stator volume (like the volume of bearing and shaft) - if the bearing and/or shaft of the motor is larger. when comparing two motors we may think we are getting more volume, but how would that non-working volume affect the calculations that you are making here?... Were bearings and shaft sizes the same for the motors in the comparisons you were making? .... (for example I looked at the bearing size of the VY2004 motor, it was 7x3x3 - The FPV Cycle 21mm has a 3x8x4mm bearing --- These inner stator volumes are different, but were not taken into account in the volumetric calculations) ... ( I love that your videos inform us all and compel us to think about motors that drive our passions :)
Here is why you DON'T subtract out the volume of the motor bearings etc. This is straight from Chris Rosser when I asked him THIS VERY QUESTION lol before publishing this video. What actually matters is the surface area of the air-gap (the size of the mating surface between the magnets and the stator), multiplied by the radius of the motor. The size of the mating surface determines the force generated by the magnetic field; the radius of the motor is the lever arm length, and force * lever arm = torque. Area of the air gap = 2*pi*r*h Torque arm = r therefore Torque is 2*pi*r^2*h By pure coincidence (or by some underlying principle that is non-obvious) this is the formula for the volume of the stator. For what it's worth, Chris's theory has been validated with experimental testing.
Why are wider motors with lower volume not used on fixed wings pushers like cruisers? Since AR Wing PRO uses 2216 1250kV for 8" bi-blade, can it work just fine with 2806.5 1250kVs?
I have desyncs with this t motor pacer 2505 1850kv on 6” apex Hd drone. I tried many esc settings and still same. In hard rolls with aded throttle it has desync.. do you know what is the problem and is this motors good for 6”?
I like your idea about annotations to amplifly your points but if you need to pause the video to read them completly it just disrupts the viewing flow. Just put the source in it for additional information.
6:09 I swapped out the 2207 1800kv for the 2306 1755kv on the Evoque F5D analog and I didn't notice any difference in torque or snappiness but I gained a lot more flight time, however on the Nazgul5 v2 using a HobbyWing 60A 4in1 ESC using the same 2306 1755kv XING2 I can definitely tell that I lost torque and I honestly don't get it because the Evoque is heavier than the Nazgul5.
I put fpv cycle 25mm 1870kv on my evoque and ot made it perfect. Evoque is a heavy beast and those xings weren't cutting it. Especially with a hero 9 on
@@djilly75 yes on the evoque I get more low end torque but not on the Nazgul5. I put the 2207 back on the Nazgul5 and it performs better but not perfect as I'd like. Idk if I should play with the timing in the blheli configurator
Dang it joshua... after you do ur tag line i NEED the little music intro thingy with your name following... i wait for that shit.. im neurotic , what can I say 😛👍
@@JoshuaBardwell size, weight and stator volume I think 🤔 Bob was the very first AFAIK to manufacture “the secret sauce 5 inch motor”. The idea is that with the patent there will be less “copy-paste” and/or Bob will be able to earn funds to continue his R&D. This is just a thought, I am no way expert. Been watching your channel and Bob’s for ages, grew up on all that info and very thankful for all your efforts and input into our mutual hobby world wide 🙏🏻 I am from Ukraine, I had to leave my home and all my FPV gear behind as I had no time and room to pack everything… “many thanks” to russia for “saving me and my family” 🤦🏻♂️
For an invention to be patentable, it must be original and non-obvious, among other things. So you would have to demonstrate that nobody had previously made a motor of that size, weight, and stator volume, and that it was non-obvious to make a motor that way. Basically, size, weight, and stator volume are not patentable characteristics of a motor. But truthfully, the real reason nobody patents stuff like this is that getting a patent is a long process (several years at least) and costs a lot of money. Two to four years from now, if Bob got the patent, his motor would be obsolete, because our hobby moves so fast. Setting that aside, he would need to defend the patent, and defending an American patent against a Chinese company is pretty challenging.
Sorry man. Compare your stator by functional volume. The actual volume of stator that is doing stuff. Your motor base and bearings don't do anything to generate torque. Secondly, motors don't make thrust, props do. Motors produce power to turn a prop. You can't really compare how well one motor makes more thrust compared to another without normalizing them with how both product thrust with a particular prop.
@@truggles120 Yep... but if you are doing a comparison it is important to check your assumptions, because most 22xx, 23xx, and 24xx all use the same diameter bearings so the respective functional volume is different
Here is why you DON'T subtract out the volume of the motor bearings etc. This is straight from Chris Rosser when I asked him THIS VERY QUESTION lol before publishing this video. What actually matters is the surface area of the air-gap (the size of the mating surface between the magnets and the stator), multiplied by the radius of the motor. The size of the mating surface determines the force generated by the magnetic field; the radius of the motor is the lever arm length, and force * lever arm = torque. Area of the air gap = 2*pi*r*h Torque arm = r therefore Torque is 2*pi*r^2*h By pure coincidence (or by some underlying principle that is non-obvious) this is the formula for the volume of the stator. For what it's worth, Chris's theory has been validated with experimental testing.
@@JoshuaBardwell Yep, I understand this stuff is complex and pedantic. I disagreed with Chris on that video too. And just because one smart engineer argues his point doesn't mean I take it as gospel. We have seen that bite us in the ass in this industry several times over. I just disagree with some of his assumptions that this derivation is based on. And the OD/ID ratio of the stator and the permanent magnet strength play big roles in flux density and with the Force equation having a squared term and the area isn't, the driving force in that equation is flux density.
The heat of the motor has nothing to do with the 'generation' of magnetic flux by the coils. It has everything to do with the magnetic flux density of the permanent magnets.
@Memer Dreamer wrong. Heat is the enemy of magnetism. If the magnets get hot (When you feel the motor bell that is coupled to the magnets) the magnetic field intensity is reduced. Dunno if temperature is and magnetic field strength are a linear relationship, but certainly hot magnets have much less strength than colder magnets. Hence the ‘super conducting’ materials that operate at near 0 K temps
CORRECTIONS. 25 / 5 is 5. Which gives a 5:1 ratio. 25 / 5 is not 1. I hate talking about math without a script. I accidentally put a 5 in as the 2104's height. That motor is only about 10% larger than a 2004, not 37%. Also, 2104 is a wider motor than a 2004, not taller. I'm not gonna take the video down. Just apologize for getting in a rush and sloppy there at the end.
...pretty close thou... 😅
Hey Joshua, your chapter title and Roogi's site both state the 21mm motor is a 2104, but you put 5 for the height in the cylinder volume calculator for that motor. Using the correct 4mm stator height, the difference is only 10% (not 37%).
@@TweakRacer I think I got a little carried away there at the end I was so excited to show off the technique I got sloppy. 21 is also not a taller motor, it's a wider motor. Sheesh.
@@JoshuaBardwell Totally get it. You are one of the very few who make corrections and make sure the most accurate info is out there. Thanks for all your hard work. You rock JB!
You're excused human, I admire that you are self deprecating.
Price is the only factor I've ever considered when choosing motors 😂
100% I figure a metal post destroys a $15 motor the same as a $25 motor
Eco 2 is an amazing motor for a low price
This is where emax thrives
Yo thats wild, I always just chose the best motor for the job and paid whatever. I'm buy no means rich though, so I don't buy them that often lol😂
@@djilly75 I got T-Motor Velox V2's(2306) for $13.90 each and they have served me well. 1750kv
2004 has been the ideal size for me with 4" 4S. Good power, good battery life, stays cool. Good all around.
The green are transition zones between sizes on the chart. I've got a new pickle for you to decipher too. Check out the metrics of the craft in my latest video.
Would you mind doing a video to explain the chart ? Or linking a blog post about it ?
When I started flying 1806 motors were the go to for 5” quads and quads were heavy back then. I think it was Evan who made a video a few months back flying Brother Hobby1806 motors on a lightweight race quad and they did really well. Anyhow, the bigger and bigger trend is getting out of hand. Cheers.
Interesting take. This hobby is an endless rabbit hole of information, some of which changing daily. God love ya Joshua.
If I hadn't already joined your Patreon, this video would have pushed me over the edge.
Thanks for the great video JB.
I'm off to watch the other motor videos you suggested.
Same
I’m over here still flying on RDQ 2205 motors watching this like 👀😅
As always - JB superpower. Started to look for new motor set yesterday and there the tutorial is
There toon of things you can do while design a feeling's motor.
Is all about the preferences and the way you want your curve kick in.
Another great video!
Thanks for all you do. I am thinking of building a 3.5 in quad and didn't know what size motor I should use. Watching this video helped me figure that out. So Thanks.and keep doing what you do. Keep ripping my little buddy.
Very helpful criteria for making motor selection, ty for breaking it down JB!
Thank you so much for making these connections... for me... amazing
I find 2306.5 is a pretty good balance of weight and power. Outside of FPVcycle 25mm 2306.5 in about 1700kv is what I look for to spin a lowish pitch 5.1" prop on a 650-700g auw quad.
Man JB with the finger on the pulse. I know a LOT of people looking at motors like the 2505... But having a quad around 650g or less seems to be a prerequisite.
The big question is, why fly 2505 instead of a lighter-weight 2306 or 2207. Why not just fly the 533 2207 and get the best of both worlds?
I feel like writing a web application that will show all those specs and that we can also make a comparison side by side :)
And if you want to go fancy in V2: kv and tip speed of prop after voltage and prop size selection. (Oh i just realised that's feature creep)
Thanks for the prop spreadsheet! Good info. I was bashing my head over figuring this out the last week.
I run gemfan 5143 props on my 2fiddy. Granted it's not under 250g. With 2203 2800kv on 3s and 20% cut on 4. My 2fiddy is ridiculously fast and agile to. Good video @joshua bardwell.
I run a 2107/2080kv on 6s racing and it does not get overly hot. I pair this motor with an HQ R35. It is very light and is used on a very light quad. Due to the higher kv the r35 have plenty of top end.
Some very useful information in this video, I'll definitely keep these things in mind in the future. I definitely learned something today! 😉
Love the new Informations Graphic
Bob has some pretty sublime motors. I've been using those 2104 units on a 250-350g (depending on battery) 5in build and they're really really good.
Thank you our drone Jesus! Okay, I’m referring to Zoroe’s post.
Got an iflight iH3 drone that’s getting an upgrade for a Cricket mini stack and the motors that came with the iH3 are 3300 KV motors but thinking about getting some 2204’s or 2207’s instead.
Just need to get the metrics correct for mounting the motors onto the frame.
Long motors (2212+) have been a staple in the wing hobby forever but seems like wide motors are better for cooling so why aren't they used more often? Responsiveness is not important for flying wings.
Thanks
the moment arm explanation seems backwards to me. is the stator was wheel being turned from the shat I would agree. but the motor is turning from the bell using the moment arm longer giving greater leverage on the drive shaft. I would like to see the test data on all this time to do some digging.
Dude this helps so much! Thanks JB!
I learned something in this video
Always thank you for your video .
This is exactly why I fly two eachine lal5’s nearly identical apart from one on the stock 2507 motors and my main which has tmotor f60’s which are 2207. When propped well (racerstar and jb hurricanes) you get the best of both worlds
Guess I'll be attending Bardwell University. Joshua is awesome, full of useful information, if there was a PhD of drone technology, he'd have it.
Bardwell you need to create an app to building a better drone for everybody out there all you do is add in all the specifications and you do all the math and tell us if it's good or not good
It’s a fine balance between height, width, weight, intended flight style!
Very informative, and well-delivered. Are there instances where it makes sense to use more than 1 motor type on a specific frame in order to better optimize the drone for a given purpose? Does anyone do this?
This is a good theory and it does bring together some meaningful comparison specs, however it seems to make sense to me that a wider motor like a 2505 compared to a 2207 would have more leverage to spin the props considering the power is generated further away from center (prop shaft). Thus would be easier to spin the prop creating faster responsiveness, but give up top end rpm speed because of the rotating mass further away from center. Like a figure skater initiates a spin with a wide stance to get the rotation going, then pulls the arms in tight to speed the rotation up. If that makes sense?
Please watch Chris Rosser's video linked in the description to see why that isn't true.
In short, for 2 motors of the same volume, a larger diameter motor has a shorter magnet which means it has smaller mating surface between the magnet and the stator. This basically exactly cancels out the additional torque created by the longer lever arm (force generated further from the shaft). That's what I remember but go watch his video for the real scoop.
@@JoshuaBardwell Got it, that makes sense. Thank you JB
i totally agree with you. i put a link below to a video about 2406 motors and he share the same view as you too in real life testing. it's not just one person but many people have that same feelings towards wider motors, so there have to be some true to it.
if you watched Bob Roogi's videos that came out a few years ago. he shared the same view too. and that's the reason he's made 25mm motors for heavy 5" quads and not 2208 motors.
i'm not saying Chris Rosser is not smart or not knowledgeable in the matter. but i'm saying he's not always right about everything. science is there to explain phenomena, not the other way around.
ruclips.net/video/yta6HwIV5Ew/видео.html
i have 1106 4500kv and 1404 4500kv motors. i'm going to test them with my 2s 4" setup. why 4" and not 3" ? and why low voltage ? well, overpropped and low voltage is where the true will come out.
even if i'm wrong i'll still make a post about it and admitting that i'm wrong. so other people can learn from my mistake.
@@matthew04101 how did the 1404 vs 1106 feel?
THIS is what I needed! Thank you!
2206 is a great size. The Emax rs2206 was a superb motor but for some reason nobody seems to want that size.
Heavy freestyle quads, bigger gopros. Wide stator like the FPV Cycle 25mm gives amazing throttle resolution and that magic low end torque that pulls you out of close call dives 😆
agree, and 2205 if you fly lightweight 5" (e.g. LOS)
I would really like a video which explains what goes wrong on each "inapropriate usage" case scenario. For example, what happens when you use motors with lower kv than what you expect for that battery/propsize/payload. What happens when you do the contrary (for example use a "4s" motor with "6s" with the same prop size), and what are more or less tolerable margins.
For example, Im buidling something like the terraplane (high power 3" cinwhoop) but I only have 2306 in 1900 kv. I'm wondering what would happen if use them. Props will spin slower than needed I guess. What will happen with the amps? If not, I have 1408 in 3500kv (typically though for 3" open prop). What will happen if I use them with 3" ducted hexablades? Will the motors be damaged? What happens with the amps on the esc.
As you can see my questions respond to my "experimental" spirit in combination with the conservative one, as I dont want to breake everything...
Thank you as always!!!
Lower kv means less thrust and fewer amps, but eventually you don't have enough thrust to fly.
Too high kv means hot, overloaded motors and potential desync.
@@JoshuaBardwell Thank you Joshua! I'll may experiment with my 2306 1900kv to see what happens before I get some 2207 2500kv to put in 6s (in the 3" hexa ducted).
This is great,digested, info!
Thank you!
Wider motor has more torque. Try free spinning bicicle wheel from the outer ring and than from middle. You will notice it takes less effort to spin wheel from outer diamater than inside diameter. The taller motors with same valume as wider motor will run hotter as it takes more energy to spin same size prop. You must calculate with prop on as the friction is introduced when prop is spinning. Not different than going uphill vs free spin.
In a brushless motor, assuming the volume is the same, a wider motor is also shorter. This means it has smaller magnets with less mating area between the stator and the magnets.
You are right that a longer lever arm makes more torque. However there is another factor at play. The torque of a brushless motor is also proportional to the area of the mating surface between the stator and the bell.
The numbers work out that these two effects basically exactly cancel out. A wider motor gets more torque from its lever arm but less torque from its short magnets.
There are other things that affect the torque of a brushless motor such as copper density in the winding and the design of the stator and the air gap between the stator and the bell, but these are basically all the same for modern quadcopter motors.
As a result, the main thing that affects motor torque is volume of the stator. This has been validated with bench testing as well.
For a layman that doesn't want to understand how electric motors really work (winds, poles, size of wire, etc, etc), I would first decide on prop size and battery cell count (voltage), then target a kv rating (range) to match. For example, for a 6S batt on a 7" prop on a mini quad, i'd be between 1200 and 1500 kv. To make that determination, I'd look at the amount of current the motor can handle, the thrust, then size, weight, and reliability, then dive into efficiency by looking at thrust for given props and amperage. The volume of the stator is of little value in the decision making process. In actuality, the bling of the bell, is the most important factor.
Roogi is a legend
I think that in calculating the torque is always missing something that in my opinion is very important.
This thing is the arm on which the torque applies.
The fulcrum of the torque is actually the rotational center of the motor shaft, and the arm is obviously the the distance of the magnets from it.
The greater force that the motor must win is the break of the prop spinning in air.
It also applies on the motor shaft.
So we got the powering arm and the resisting arm of the torque. Someone should bench it.
Fascinating, Joshua.
I would use this motor on my Nano Talon Evo plane. I'm running a 2306 1400KV right now. For a drone I'd probably use it on a 7" long range cruiser 😎🤙
The most important spec for picking a mini quad motor is.... cost.
Followed by availability (will I get replacements when I burn out a motor?).
bardwell says hit thumbs up i hit thumbs up. appreciate the content.
I noticed that chart(kabab fpv) doesn't list the lower end motors for micros ie 0802 etc.dont forget us little guys. we don't all want big 4/5" quads.be handy for all the WHOOP racing guys too since that is a Big sport.
recommended Prop Diam in inches = Squared Root Of ( Stator Volume (mm³) / Constant (87.5) )
gets you pretty close to ideal prop diam. got it from the graph on Chris Rosser's motors video where he shows the graph but not the formula. i got an excel sheet with some of his formulas and it has become a great starting point for me
Does the constant change between motor sizes? Plugging 2306 (pi*23^2*6)motor into that equation yields about 10.5 inches
@@XBionicMC stator volume should be r×r×π×h so in your case a 2306 motor should be 11.5×11.5×3.14×6 = 2492mm³
So squared root of (2492/87.5) = √28.48 = 5.34" props.
This should be a starting idea as noted in Chris videos where he points out that the prop pitch and weight and other factors of various sources could affect your choice.
For example I went for a small 2.5" quad and used 1404 motors. In my case stator size= 7×7×3.14×4 = 615mm³. Ideal prop size = √(615/87.5) = 2.65". I was planning to use avant rush props which are known to have an aggressive pitch so I figured it was just about right. And even if a 1404 sounds like a huge size motor for a 2.5" quad, it actually feels amazing and solid. Then I found JB's Transtec Beetle 2.5 HD review and it all made sence.
3.5" props ideal motors are 1506 or similar stator volume, but Chris recommended for his aos3.5 frame some 1404 motors to use the digital video unit and keep the weight under 250 grams, so it's all in your needs.
Excellent as always
Torque can not be calculated in cilinder volume of motor as KV coper winding give differential valume.
More coper winding generates more torque. If yuu realy want to measure anything than it be the coper volume.
Wonder if heat build up is why I put 8" props on over 7" & lost some top speed 🤔
Under size motors also 7" was on betaflight & better setup. 8" on inav & not set up smoothly. Might lost to oscillations
Very interesting and informative video.
Could you please compare these T-Motors to Bobs motors? For people outside the US its very hard to get Bobs motors without paying huge shipping costs so this T-Motor might be our only option.
Tmotors have less volume right? Bobs are 2506.2. the difference in volume over 2505.5 is not insignificant. Bobs are also super light. Durability is a major concern on the FPVCycle though.... Bell walls seem thin and don't like concrete
@@mouseFPV yeah quite a lot less volume, bobs have 3000 and the tmotors have 2400, the same as a 2306...
what about Turns and wire thickness.. That also plays a huge part in Torque and rpm.
Watch Chris Rosser's video.
Another great and informative vid. What will happened if I I miss match one motor - kv wise? Motor I need is unavailable.
Great video, thanks!
I don't know why I would do these calculations and thinking about stator volume when all the data I really need is already in the datasheet (1:38). Power, torque, efficiency, thrust and and temperature at different RPMs and for different prop sizes - what more could I ask for?
This whole discussion depends on entirely on the assumption that the motors are of equal quality. A motor the looks superior on paper may be hamstrung by poor quality magnets or an oversized airgap.
Love this thanks Josh
Good stuff man
Let me save everyone some time. 2207 is the perfect freestyle motor for almost every 5" quad. if you have a very heavy quad like 800 to 900 grams then go with a 2208. it's that simple. Well at least if you are in it to have fun with plenty of power. No offence intended Mr Bardwell. This has just been my experience with testing many many quads.
Nice
Learned a lot in this one Josh, thks! Been wondering though, as you mentioned the 2 common examples of alternative motors in this vid: what alternative motor could you compare the Brotherhobby 2507 v2 1700kv against? Is there any in that category?
Shouldn’t we substract the volume of the bearings etc? Given we gave the same bearings you have to substract more on a taller than on a flatter motor.
No. Chris Rosser's video explains why. What actually matters is the surface area of the air-gap (the size of the mating surface between the magnets and the stator), multiplied by the radius of the motor. The size of the mating surface determines the force generated by the magnetic field; the radius of the motor is the lever arm length, and force * lever arm = torque.
Area of the air gap = 2*pi*r*h
Torque arm = r
therefore Torque is 2*pi*r^2*h
By pure coincidence (or by some underlying principle that is non-obvious) this is the formula for the volume of the stator. For what it's worth, Chris's theory has been validated with experimental testing.
Fantastic info, Joshua! Thanks a bunch! 😃
Stay safe there with your family! 🖖😊
BTW, 2104 is taller or wider than 2004?
2104 is wider - The first 2 digits are the width of the stator in mm, and the last 2 digits are the height.
@@Wild_FPV Yeah, that's what I thought.
Jesus. 😞 Sloppy...
@@JoshuaBardwell Don't worry, Joshua! Those things happens!
at 5:00 you write that the motor is 2550 but its is in fact 2505 for average flyers we understand what you mean, but for newcomers...that's a big motor!
How much more responsiveness do you want the 2fiddy to have lol
2205 on a 4” HD apex is pretty damn dialed I must say
For racing, these days the most important spec is whether you can use it for freedom spec.
Would Kabab's spreadsheet map onto fixed wing use as well?
That chart doesn’t take into account thrust to weight ratio either
T-Motor MCK 2207.5 V3 2100KV Motor would this be really fast on 6s??
Joshua... I am puzzled... Volume measured solely on the outer dimensions of the stator... makes me ask, what about the inner dimensions of the stator volume (like the volume of bearing and shaft) - if the bearing and/or shaft of the motor is larger. when comparing two motors we may think we are getting more volume, but how would that non-working volume affect the calculations that you are making here?... Were bearings and shaft sizes the same for the motors in the comparisons you were making? .... (for example I looked at the bearing size of the VY2004 motor, it was 7x3x3 - The FPV Cycle 21mm has a 3x8x4mm bearing --- These inner stator volumes are different, but were not taken into account in the volumetric calculations) ... ( I love that your videos inform us all and compel us to think about motors that drive our passions :)
Here is why you DON'T subtract out the volume of the motor bearings etc. This is straight from Chris Rosser when I asked him THIS VERY QUESTION lol before publishing this video.
What actually matters is the surface area of the air-gap (the size of the mating surface between the magnets and the stator), multiplied by the radius of the motor. The size of the mating surface determines the force generated by the magnetic field; the radius of the motor is the lever arm length, and force * lever arm = torque.
Area of the air gap = 2*pi*r*h
Torque arm = r
therefore Torque is 2*pi*r^2*h
By pure coincidence (or by some underlying principle that is non-obvious) this is the formula for the volume of the stator. For what it's worth, Chris's theory has been validated with experimental testing.
@@JoshuaBardwell You are amazing Joshua. Thanks for answering my question and helping me really learn something today :)
Why are wider motors with lower volume not used on fixed wings pushers like cruisers? Since AR Wing PRO uses 2216 1250kV for 8" bi-blade, can it work just fine with 2806.5 1250kVs?
Where can we find a break down of that graph by Kabab. I can’t find it online. I’d like to know what each color means if possible.
I have desyncs with this t motor pacer 2505 1850kv on 6” apex Hd drone. I tried many esc settings and still same. In hard rolls with aded throttle it has desync.. do you know what is the problem and is this motors good for 6”?
Wow, with how light this is it makes me wonder why the Fououk motors are like 38g holy smokes.
I wondered the same.
Yo… What’s with that t shirt Josh?!
I need one to replace my “ Fear the Scragle “ one. 🤨
I like your idea about annotations to amplifly your points but if you need to pause the video to read them completly it just disrupts the viewing flow. Just put the source in it for additional information.
Has anyone tried the Five33 2207 motors on a 5" freestyle build?
When talking about 8% smaller, the popup talks about 2550 motors (in stead of 2505). Almost shit my pants: those are some huuuuge motors
6:09 I swapped out the 2207 1800kv for the 2306 1755kv on the Evoque F5D analog and I didn't notice any difference in torque or snappiness but I gained a lot more flight time, however on the Nazgul5 v2 using a HobbyWing 60A 4in1 ESC using the same 2306 1755kv XING2 I can definitely tell that I lost torque and I honestly don't get it because the Evoque is heavier than the Nazgul5.
I put fpv cycle 25mm 1870kv on my evoque and ot made it perfect. Evoque is a heavy beast and those xings weren't cutting it. Especially with a hero 9 on
You'll notice the 2306 have more torque in the lower throttle. Pulling out of steep dives
@@djilly75 yes on the evoque I get more low end torque but not on the Nazgul5. I put the 2207 back on the Nazgul5 and it performs better but not perfect as I'd like. Idk if I should play with the timing in the blheli configurator
@@BOOST_FPV lower your pwm frequency to gain more torque or get some 2506.5 imperials 😆
I wouldn't drop pwm on that HW 60a. Lock at 48khz since those only go to 48khz. Are you wanting more low end resolution?
Dang it joshua... after you do ur tag line i NEED the little music intro thingy with your name following... i wait for that shit.. im neurotic , what can I say 😛👍
Has anyone tried building in a centrifugal flywheel for lower response but longer flight time?
No
Kabab should patent all his motors 👍🏻
Which aspect of his motor is eligible to be patented?
@@JoshuaBardwell size, weight and stator volume I think 🤔 Bob was the very first AFAIK to manufacture “the secret sauce 5 inch motor”. The idea is that with the patent there will be less “copy-paste” and/or Bob will be able to earn funds to continue his R&D. This is just a thought, I am no way expert.
Been watching your channel and Bob’s for ages, grew up on all that info and very thankful for all your efforts and input into our mutual hobby world wide 🙏🏻
I am from Ukraine, I had to leave my home and all my FPV gear behind as I had no time and room to pack everything… “many thanks” to russia for “saving me and my family” 🤦🏻♂️
For an invention to be patentable, it must be original and non-obvious, among other things. So you would have to demonstrate that nobody had previously made a motor of that size, weight, and stator volume, and that it was non-obvious to make a motor that way. Basically, size, weight, and stator volume are not patentable characteristics of a motor.
But truthfully, the real reason nobody patents stuff like this is that getting a patent is a long process (several years at least) and costs a lot of money. Two to four years from now, if Bob got the patent, his motor would be obsolete, because our hobby moves so fast. Setting that aside, he would need to defend the patent, and defending an American patent against a Chinese company is pretty challenging.
What about the volume math? do I have to say it?
And the video with Chris, Ryan, and Bob would be where?
Pops up around 17:20 mark
There's a pop up card at the end of the video. Of you're watching on a device that doesn't show end cards I guess you might not see it?
Here is the link: ruclips.net/video/Y8HYoRXBQW4/видео.html&ab_channel=JoshuaBardwell
@@JoshuaBardwell ok thanks
Hello jb, i facing desyncs on pacer 2505,
I am all fucked up ,can you help me
Set demag compensation to high?
@@JoshuaBardwell it's at low, 48khz motor timing 16
Set it to high.
And increase timing.
Sorry man. Compare your stator by functional volume. The actual volume of stator that is doing stuff. Your motor base and bearings don't do anything to generate torque.
Secondly, motors don't make thrust, props do. Motors produce power to turn a prop. You can't really compare how well one motor makes more thrust compared to another without normalizing them with how both product thrust with a particular prop.
The size shown by the motor name like 2207 is the stator size
@@truggles120 Yep... but if you are doing a comparison it is important to check your assumptions, because most 22xx, 23xx, and 24xx all use the same diameter bearings so the respective functional volume is different
Here is why you DON'T subtract out the volume of the motor bearings etc. This is straight from Chris Rosser when I asked him THIS VERY QUESTION lol before publishing this video.
What actually matters is the surface area of the air-gap (the size of the mating surface between the magnets and the stator), multiplied by the radius of the motor. The size of the mating surface determines the force generated by the magnetic field; the radius of the motor is the lever arm length, and force * lever arm = torque.
Area of the air gap = 2*pi*r*h
Torque arm = r
therefore Torque is 2*pi*r^2*h
By pure coincidence (or by some underlying principle that is non-obvious) this is the formula for the volume of the stator. For what it's worth, Chris's theory has been validated with experimental testing.
@@JoshuaBardwell Yep, I understand this stuff is complex and pedantic. I disagreed with Chris on that video too. And just because one smart engineer argues his point doesn't mean I take it as gospel. We have seen that bite us in the ass in this industry several times over. I just disagree with some of his assumptions that this derivation is based on. And the OD/ID ratio of the stator and the permanent magnet strength play big roles in flux density and with the Force equation having a squared term and the area isn't, the driving force in that equation is flux density.
Fair enough. At least you're an informed disagreement 😝
Size matters 😝
Wider motors and higher moment of inertia could also result in a more smooth performance due to the dampening effect of the rotating mass.
They would also be more susceptible to vibration due to small imbalances, which I suspect might dominate the other effect.
The heat of the motor has nothing to do with the 'generation' of magnetic flux by the coils. It has everything to do with the magnetic flux density of the permanent magnets.
@Memer Dreamer wrong. Heat is the enemy of magnetism. If the magnets get hot (When you feel the motor bell that is coupled to the magnets) the magnetic field intensity is reduced. Dunno if temperature is and magnetic field strength are a linear relationship, but certainly hot magnets have much less strength than colder magnets. Hence the ‘super conducting’ materials that operate at near 0 K temps
@Memer Dreamer I think we are getting at the same point, but with misunderstood comments lol
HOW much money do I have left.
Awesome Video Like 401!!
I miss all the ASMR-ish Kabab videos endlessly ranting about props or whatever.
I only fly tru pancakes 3002 sned it.
Здоров!!! RUclips мне показывает твоё видио бесплатно, без рекламы✌😜
I will click the like button because I learned something in this video
*beep beep*
*initiate liking routine. beep*
If you see this you should turn that lava lamp on next video please :0.0
The lava lamp is broken :-(
buy them and fly them, talk at the dinner table is only half the equation