The most important spec for picking a mini quad motor is... 

...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.

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

Would you mind doing a video to explain the chart ? Or linking a blog post about it ?

Same

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?

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)

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).

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.

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)

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 :)

Watch Chris Rosser's video.

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.

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!

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. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-yta6HwIV5Ew.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?

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?

No

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...

Set demag compensation to high?

@@JoshuaBardwell it's at low, 48khz motor timing 16

Set it to high. And increase timing.

I wondered the same.

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.

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.

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: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-Y8HYoRXBQW4.html&ab_channel=JoshuaBardwell

@@JoshuaBardwell ok thanks

@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

They would also be more susceptible to vibration due to small imbalances, which I suspect might dominate the other effect.

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 😝

The lava lamp is broken :-(