Solving the BIG PROBLEM I have with DIY Drones! (Motor Test Stand)
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In this video I will finally get one step closer to building my own DIY drone. Because in this episode of DIY or Buy we will be having a look at drone motor test stands and obviously build a crude DIY one as well. With such a stand you can measure at what RPM/Power your motor creates what RPM with what thrust. This information is more or less crucial when making your own DIY drone. So let's get started!
Websites which were shown/used in the video:
www.tytorobotics.com/products...
Thanks to Keysight for sponsoring this video.
0:00 What Drone Problem?
2:00 Intro
2:40 What do I need to measure?
4:34 Buy Option Test
5:53 Motor Test Results
7:48 DIY Option
9:57 Verdict - วิทยาศาสตร์และเทคโนโลยี
I am not sure why, but when it comes to drones then I constantly make mistakes. So if you got good guides/information/parts you would like to see in the final drone video then let me know :-)
An expert is someone that's made all the possible mistakes in a very precise domain. So yes, consider you're slowly becoming an drone expert.
Thanks for the motivation ;-)
@@greatscottlab you can do this!
@@greatscottlab love the intro too!
How the- this video is like 12min ago posted but this comment is from 12 days ago WHAT THE CRAP
Low kV motors are also meant to be used with very large propellers. Tip velocity is important; you can't have a large radius propeller being spun at high RPMs or the tips will approach the sound barrier, become very unstable, and oscillate until they destroy themselves.
Exactly! That's why 5" drones use higher kv motors and 7" (with 7" props) use lower kv motors. And adding the benefits of 6s makes them even more efficient.
I still want a modern attempt at a Thunderscreech dammit!
Cost about 300$ or how ever much your drone cost,
Because it’s going to crash! But sound is unforgettable and worth it lol
lower kv gonna be heavier too
What happens when the propeller breaks the sound barrier?
Some handy tips to have in mind while choosing your Motors and Props:
-The Maximum tip speed of your Blades should not be more than ~0.62 Mach (0.59 Mach is the optimal max tip speed). Because at even higher speeds the blades will start to significantly compress the air in front of it which will increase drag and decrease efficiency.
-Most Motors have a similar flux density so you can compare them with the stater volume π*(r^2)*h instead of calculating the actual Torque with T = (B^2)*π*(r^2)*h/μ_0
(B^2 as the magnetic flux density and μ_0 as the magnetic permeability of the space between them)
-With two motors of the same mass and volume:
A narrow tall motor bell will have much less rotational inertia and therefore be much more responsive. However it will be much hotter.
A shorter wider motor bell will be less responsive but much cooler because it has a larger surface area on top through which the movement of the blades will push air and cool the motor windings.
A typical ratio of diameter:height would be minimal 3:1 ore 4:1 if you fly like like a madman.
-A high KV motor’s torque reduces more slowly with RPM but will require more current to produce a given torque (this can lead to the battery being the bottle neck if it is not able to provid the needed current)
-The actual current draw (as well as the required trust for a given tip speed) will be lower than on the test stand due to a phenomenon called prop deloading. If you use a higher throttle you are probably flying faster which creates headwind in the direction of your props and therefore deloads them.
-A lager angel of attack (up to ~16°), more blades as well as a larger diameter of a propeller will all increase thrust.
-A larger diameter propeller is more efficient due to disc loading. (disc loading is gross wight / thrust area ore the quads weight distribution on the covered prop area) The propeller will produce more thrust per watt
-More blades reduce prop efficiency due to the wake from preceding blades disturbing the flow
-A larger angle of attack increases prop efficiency (up to ~8°) due to Stall
The fixed angle of attack is the fixed pitch = arctan(p/π*d); p = pitch and d = diameter
Angle of attack = fixed pitch - arctan*(V_inflow/w*r)
W*r = the tip speed of the propeller
V_inflow is the inflow velocity.
~V_inflow = 1/2*(√[m*g]/[p*π*r²]); m = the mass of the vehicle, g = the gravitational acceleration, p = the density of the air and π*r² = the area of the prop
A lot on this list is not mine but from Chris Rossers channel (sorry if this seems like advertising for another channel but especially the formulas are his and not mine so I have to give him credit)
I personally found an low KV system with bigger Motors and lower Voltage (something like 4S is fine) plus two bladed props the most efficient. If you have to chose between two Motors get the bigger one and throttle lock it through the flight controller. Try to get the current draw low enough so that you can use custom lithium packs and potential double the flight time.
Personally, I think your approach of starting with the motor first isn't really a good idea. The proper way is to determine your needs first and then go from the most restrictive specs to the least. This is important, especially with trial-and-error approach as changing the most restrictive specs will be challenging and oftentimes means starting all over again.
When coming up with a quadcopter, I'd start with the payload first. What kind of load I'll be strapping on? What is the size and weight? You'll need bigger quadcopter with more load obviously, and the quadcopter size comes in either motor-to-motor wheelbase (450mm) or propeller diameter (9"). Generally, a quadcopter with 7" prop should handle up to 200g. I'd push up to 500g for a 9" quadcopter. There isn't any absolute guideline on this because every system performs differently, but it should give you a good approximation of what frame you should settle with.
With the suitable wheelbase picked, then comes the propulsion system. Just go with the recommended setup for that particular size and you should be good to go. For example, the 450mm frame I mentioned is optimized for a 9" to 10" propeller. Typical 9" propeller requires motor ranging in size of 2208 to 2312 to spin. For the KV, it comes down to what electrical specification you want to go with. For a 4S system, the setup requires motor in the range of 920 KV. For a 6S system, the setup requires motor in the range of 610 KV. Basically, pick the frame and propeller size. Motor size has to be enough to spin the propeller, and the KV has to be enough to give the speed for thrust generation, while not being overloaded by the propeller.
The battery can be a bit tricky, but it's very forgiving. Unless you're looking for absolute efficiency or a mission that requires the battery to last down to 10% of the charge. There's no need to calculate the most optimum battery size and you can trial-and-error it if you want to. Then, the electronics are the least restrictive here. Determine the ESC capacity by the maximum theorized current and voltage. For the previous setup, a 25 and up 6S ESC will do the job. Pick your favorite flight controller that will do the things you'll throw at, probably like GPS support or autonomous missions. The rest are pretty much up to you.
Just because you started your project since 2016 doesn't mean you have to be stuck with the technology coming from back then. The industry in quadcopter has come a long way since then, and more and more hardwares are released that are cheaper, more capable, and way easier to work with. Some of the performance motor classes have improved that it might worth forking over, while general usage motors are pretty much the same. The electronics have improved a lot in the recent years. ESCs that won't randomly kamikaze mid-flight and come with 32-bit MCU, hardware PWM, and dedicated driver that runs silent and more efficient. Flight controllers with capability to fly a quadcopter with 4 different propellers and motors easily, or even be configurable from a smartphone with standalone app. Open-source control transmission with LoRa modulation that can do 30 KM on a legal power level and 2.4 GHz frequency. HD video transmission system that can broadcast 720p image with less than a tenth of second latency and 10's KM of range.
And talking about your approach on testing the motors, there are a lot of things to consider. With the given input power and propeller combination, the two favors the smaller motor despite it won't be optimized for your purpose later. The larger motor requires larger prop to drive and will beat the smaller motor in terms of efficiency and low-speed thrust generation with optimized setup, the two you'd be looking at for the class you're the most suitable for. It's good for educational purpose, but I won't make any conclusion out of it.
Will be updating this guide later.
Thanks for the feedback so far :-)
this is the correct answer!! in systems engineering we have a formalized version of this process: in a nutshell, first, you define your needs, then find out what needs to be engineered and what is already available off the shelf, then define what each engineered subsystem needs to do, and eventually you get down to component-level requirements, and from there you can start sourcing components!
Wow
When you already have a motor that you want to use. Starting by checking what that motor can do is basically to determine the most restrictive spec.
After you now what the motor can do you design the rest based on that. Good motors are expensive so if you can use something that you have you should.
@@greatscottlab From what i've observed, you dont really need a stand. Just calculate your max weight plus a bit of headroom, multiply that by 2 or 2.5 and you get your desired maximum total thrust. Then divide by the number of motors, then go motor shopping. Most if not all motors today have handy charts that tell you what size propeller produces how much thrust at what efficiency. Just search the name of the motor you're considering and look at google images. After finding your motor-propeller combo this way, just pick an esc that has %25 percent more capacity from the maximum load the motor manufacturer has stated.
Great video. I've spent a ton of time doing automated motor/propeller testing (post some results on my channel) and the biggest problem with most methods using thrust stands is controlling static thrust testing variables. The biggest two are input voltage and heat. If you can eliminate those variables, I've found you can get extremely accurate repetitive test results which is great for comparative testing. All you need to do is use a high current output bench supply and burst motors for short periods to test at each point allowing them to cool down before hand (ramping will cause them to quickly heat up and sag the voltage/thrust output). With your thrust stand you can accomplish this with some automation and get a ton of samples over a few hours. Feel free to reach out if you want to get more information.
Dude, today we have 4in1 escs. One board where you solder all the motors. About efficiency, look for long range quadcopters. Dave_C has some fantastic designs!
Freestyle quads, on the other hand, fly for about 5 minutes at most, because it's all about the acrobatics, so it needs a lot of power.
Racers, in the other hand, are all about the lightest and more powerful possible... And there are races in Germany, so look for one of those events!
Anyway, I'm definitely looking forward to see what you're going to end up building! 😃
Stay safe and creative there! 🖖😊
@@maxhouseman3129 It depends on the size. Up to 10" propellers you can still use 4in1. And judging by the motors he has, I can't see something that big.
@@maxhouseman3129 You probably run ArduCopter? Or you mean Beast Class/X Class quads?
@@maxhouseman3129 Oh, sweet! 😃
That sounds like a dream job!
In my case I only fly FPV quadcopters, for hobby. You know? The first thing closer to a professional build I'm going to do is going to be something similar to the old TBS Discovery... But with 2012 technology! I'm going to use the DJI NAZA Lite! 😂
In my opinion the DIY is the winner. For building drones as a hobby there is not even a test stand needed. I built my drones without owning one. There is a ton of information out there what motors, escs and props go together dependent on your payload requirements.
I'm excited to see how your drone turns out in the end.
Thank you. I have no idea how an electrical ingeneer can struggle with building a drone. I just think he is overthinking it.
I’ll be honest - I usually just look for prop tip speed to choose KV and lipo and then „tune“ the rest with different pitch props… (oh, and the needed power can be estimated quite well with stator volume, there’s a drone dude called pawel something who made a list with roughly needed stator volume for a given typical prop diameter)
Been following/watching your videos for many years now my friend. You inspire me.. I want to work on projects like you do but I lack any real workspace to do it. So I live vicariously through your videos. Thank you for every thing you do :D
I strapped my motor to a weight and put the whole thing on some scales
I measured the weight of the whole assembly not running, and then running at various speeds 25, 50, 75 and 100 %
By subtracting the various results from the "at rest" weight, I could figure the lifting capacity of various prop/motor/ ESC combos without the need for an expensive testing stand
This has probably been said, but the propellor you use makes a HUGE difference too, low kv motors spinning a large prop are generally the most efficient, larger props can spin slower for the same amount of thrust which creates less turbulence so it's a lot less wasted energy.
The lower the number of blades also has an impact on efficiency, ideally a single blade with a weight is optimal, but it's not a huge performance difference from just two blades, but going from two to three blades makes a large difference
Exactly what I wanted to say. In aviation there's a saying "2 blades for go, 3 blades for show."
@@wesleyson21 The increase in blade count is usually due to the power produced by the motor and the diameter of the prop being limited. That is why the Spitfire ended up with a 5-blade prop once the power produced by the engine had increased. They couldn't increase the diameter of the prop so you had to add more blades. I believe it went from 3 to 5 over time as the powerplant got more powerful.
Scott, I absolutely love you and your brain.
You keep making electronics easy to understand. It's given me tons of inspiration for a particular project I've had in mind since I was a child, and now I think I can pull it off, even if it's not as "Sci Fi" as id like it to be. Thank you!
Hi Scott! FPV pilot here: some suggestions I would have are to use a motor from a more reliable brand (Lumenier, T-motor, RCinpower, EMAX, and some others), I'd suggest propellers that are perfectly balanced as it can interfere with your onboard gyro from all the vibrations, making more filtering needed, and more phase delay. Some brands of propellers I suggest for big quads are from HQProp, their 10x5x3s are good, they also have 9x5x3 and 8x5x2s. Master Airscrew also makes great propellers for the 8-13" diameter range. I'd also suggest using a flight controller firmware like iNAV for it's autonomy features and a lot of community support (although I'm extremely biased on that 😂). Using a newer firmware with a newer ESC (like a 4-in-1 ESC) would give you the ability to use an ESC communication protocol like DSHOT. Some newer flight controller firmwares like iNAV, Betaflight, and emuflight are capable of bidirectional dSHOT, which allows your ESC to report back RPM and more data to the flight controller, allowing you to use RPM filtering. RPM filtering allows the FC to smartly target the specific noise frequencies the motors are generating.
I'm however, a FPV pilot and I build fast racing quads, and occasionally big 10" racing quads. I understand some of these might now apply to you because it seems like you want a more efficient slow flying build. But hey, anything helps!
Also many reputable brands offer recommended propellers, and what kind of voltages they used for testing along with the thrust and current at that voltage. With just a bit more time investigating you could get an efficient setup for different weights of drone. Usually for a slow flying drone a thrust / drone weight ratio of 1.5 is good but I would go for 2 for more efficiency based on experience...
I love how you have the max voltage in mind for future selection of components, thus giving 1S 4.2V instead of the standard rating of 3.7V. Shows how much you are wanting to go for the absolute max on the cell count.
There's a trade off between reaction mass, efficiency, thrust, weight, etc. You can calculate the thrust to weight ratio of a motor, propeller and power input combination. There are impractical numbers of combinations of propeller designs, materials, blade numbers, airfoil, materials, etc. Some practical testing is necessary. I've built many custom drones and I can say rarely do they work right on the first attempt. It's amazing how the flight characteristics vary based on small changes. Tuning is half the fun :)
Weird that no one seems to have recommended ecalc yet.
It can be confusing as it has _a lot_ of fields and stuff to type in, but it is pretty accurate and it's better to try stuff out in a calculator than buying all the stuff without knowing if it will work
that's exactly what i was thinking to write @GreatScott! please consider googling ecalc !!!
Lol just mentioned motocalc...was first thing that popped into my head. Great tools those
The kit you have originally came out in the early years, it's improved night and day since then... Even the cheap stuff. Escs, motors and battery upgrade would significantly improve everything needed... Speak to Bardwell
This is nice, I just made a forged carbon drone frame. It was my first time working with compression molds so I filmed everything.
As motors go, I would recommend the IFlight Xing series. They are great motors, affordable, efficient, and have decent documentation. You can get something like 2814 for 9-12 inch props and 16/24V. Or you can go with 2806.5 for 7-9 inch props and 16/24V. That gives you over 2kg of thrust per motor on 100% in both of those cases. And you can get them for like 30-40 euros per motor. There are some other nice manufacturers like Diatone, BrottherHobby, etc.
They will pull 40-50 amps but with those, you can make decent cinelifter.
Great video! I usually do get the correct power rating, as I only choose motors with thrust documentation. Usually, I go for a 4:1 power ratio.
Thanks for the tip :-)
@@greatscottlab Also I forgot to mention that I usually use motors that are slightly more powerful than needed, as running a powerful motor with a large prop at lower throttle is way more efficient than running a weak motor at a higher throttle. If it is too powerful, depending on the flight controller you use, you can tune the motors down. Some sophisticated flight controllers may let you specify a maximum throttle. With flight controllers that don't, I find that tuning the gain and adjusting the endpoints on the controller should help. Good luck with the drone!
This is exciting to see you plan to do a DIY drone. I'm looking forward to seeing it!
That's a lot of work, thanks you so much !
Great and educational content as always! Looking forward to the actual drone build!
For stability control of the quad copter could you use tilt switches (or something more sophisticated like an angle sensor) and a pwm voltage to power the motors so the copter self corrects by augmenting the voltage until it stabilizes?
wow .
A good educator
Well done!!! Thanks for sharing.
Awesome to see you building drones!
Can't wait for the next video 🔥🔥
DIY is the winner... It can take a lot of work/time/money to get it just right, but when you get it just right.....so GOOD!
Wow, I didn't know I could buy a test stand like that, thanks for the info
I'd recommend also building a shaft-to-shaft dynamometer. There's a certain point where either the motor stops delivering torque, or the ESC stops delivering current. Better to find those points on the ground rather than in the air.
It would be interesting to see the transient step response of motor and propeller combinations for a given supply voltage. This is important for fast control loops and an aircraft the feels responsive, but to my knowledge hasn’t been characterized in the multi rotor community.
Also if you jump to a 4s battery, you should be able to get about a kg of thrust out of that rs2205 motor, but it’ll pull a few hundred watts. This was my favorite motor when I used to fly a lot due to its high price:performance ratio. Great video as always!
Cool, thank you for sharing this project as I can see many uses for this.
Glad it was helpful!
Awesome, can't wait to see your next step in this drone build !
Me neither ;-)
I gave it a shot aswell a few days ago and got confused by the exact same issues you mention at 1:00!
Structural is all planned, center piece and motor mounts are designed to be easily scalable but boi did I get deep into the rabbit hole of aerodynamics and still haven't decided which components to combine
IT'S FINALLY HEREEE
There's a lot to write here and it's 3:30am, so I don't know how much I'll fit into this comment, but I'll try ;)
-You're using very old tech! Motors, ESCs, prop design and batteries have changed a lot since 2016. I'd suggest researching a bit on the newer tech and getting something that might be better suited for what you're doing. A great channel to follow are Joshua Bardwell, which mainly focuses on 5" drones (the "standard" for acro, freestyle or racing), but a lot of that stuff translates very well to other sizes and shapes as it's all very modular and interchangeable. A GREAT resource (no pun intended) is also Oscar Liang's website. There you can find pretty much everything! Pay attention to when the articles are posted though, as he's been around for a while and some of them are pretty old! Joshua Bardwell also has a website, with broader tips and sections where it points you at what to get for your needs more directly. Great to not feel overwhelmed when you first start! Much of the stuff I write here is on there, probably written better than this, haha
-I'd suggest looking at the newer ESCs, as those are the things that have changed the most, with different protocols and firmware that allows you to really customize them in depth. Especially the ones with BLheli32, they have 32 bit controllers and are extremely customizeable.
-As for props, efficiency isn't the only parameter at play: less blades are usually more efficient, but more blades are more responsive and generally have better flying characteristics and fewer vibrations. It's a similar thing with the size, bigger is way more efficient, faster and it can carry more weight but it obviously gets heavier and less maneuverable, while smaller is more "zippy" but with lower flight times and it's slower. It all depends on what you want to do with it, and as somebody suggested here I'd say that the first and most important thing you should do is figure out your needs: long range? Acrobatics? Carrying stuff around? Close range fast fun? Hyperfocused racing around a "circuit"? Cinematic shots? All valid uses, and all with different quirks and different design choices!
As I mentioned before, 5" (prop diameter) is kinda the "standard" for most hobbyists. It's in quotes because there really is no standard and you're free to choose what to do, but you're really gonna find the most documentation and parts for 5" drones with three bladed props. The knowledge is generally scalable (unless you go really small or very big) but if you wanna go the "easy" route for a first build there's that. It's 5" because it's kind of a sweet spot between battery life, speed, maneuverability, and ease of building them. Then if you go more specific you will want to change stuff up! Want more range and don't plan on doing stunts? 6 or 7", with 3 or 2 blades is good. Want a very light drone that people aren't gonna be scared of, that will suffer a bit from wind and will have a worse battery life? A "toothpick", 3", 3.5" or 4" is for you. The other advantage is that they're also easier to keep under 250g to have less trouble here in the EU. Batteries are also cheaper to buy so the low battery life is less of a concern. Just buy more batteries! ;)
-batteries! Here the "standard" for 4", 5", up to 7" or slightly more (I'm not experienced with stuff bigger than 7", so don't quote me on that) is 4S or 6S, with 6S being the preferred one at the moment as it allows motors to be more efficient and more responsive. It's mainly for acro though, so if you're just cruising around 4S is generally cheaper. 3-4" generally are 3S or 4S, with some 4" using 6S but IMO they're extremely overpowered. "Toothpicks" and "tinywhoops" (I don't immediately recall the prop sizes, but they're the smaller ones) usually use 1 or 2S.
The battery sizes obviously change depending on size. Tinywhoops have 450-550mAh 1S or 300-400mAh 2S batteries, 3-4" I'm not sure as I don't own any (IIRC about 800mAh 4S), 5" use around 1500mAh 4S or 1100-1200mAh 6S (they generally stay at around 22Wh), and so on.
-motors, this is another can of worms! Generally the community has already figured out the ideal sizes and KV for each prop diameter/cell voltage combo. You generally want a taller, thinner motor for more performance and responsiveness but a wider, shorter motor if you want to carry weight and need the motor to have better cooling. I'm most experienced with 5" (as you might have understood), there the most common motors are 2306 or 2207 (referencing the dimensions in mm of the stator, xxyy where xx is width and yy height). It generally doesn't make much difference at all if you're not extremely experienced, but other prop sizes might have a wider range of measures, you can reference the community or other people with more experience than me in those prop sizes under here ;)
As for KV, your "acceptable range" doesn't only vary with battery voltage but also with prop diameter and prop pitch! What's important is the tip speed, you don't want it to go over the speed of sound and even if you're under it you don't want to stress the prop so much that the plastic flattens, essentially giving you a 0 pitch prop. You'll hear it as a "vvvvvWAAAAAAA" as the motor suddenly doesn't have any load on it and spins up if it happens, and you'll momentarily lose your power until you lower the throttle
Besides that, you don't want to overload the motors. So, higher KV goes with lower pitch, smaller props, or lower voltage batteries, and lower KV goes with higher pitch props, bigger props or higher voltages.
Again for 5", at 4S you're looking for a motor with a 2300-2800KV, and for 6S a 1500-1900KV. For both, I'd shoot for something in the middle as it can work with most props. Choosing a 1900KV motor at 6S will limit you to only using very low pitch props. As I mentioned before, Oscar Liang is a great resource!
My tip on motors is to not stress too much over them. There are TONS of options, that go from extremely cheap to extremely expensive. The middle is actually pretty great. Avoid the extreme low end, as you'll really just find junk that gives you way more problems that aren't worth the euros you save! I got a motor bell fly off mid-flight lol. No idea how as the C clip and the running motor magnetic field should really keep it in place... But it happened lol. 5€ motor haha
In the end, have fun! Look at the resources, decide the drone's purpose and get at it! I'll be watching the videos ;)
It's 4:50 am now so I'll go to sleep
Looking forward to seeing this one come to fruition this time round. Any kind of flying device, be it a drone or plane, requires such skill to get it right. Getting that balance of weight, correct motor speed, propellor pitch and everything else needed to just get off the ground, let alone making it stable. I don't think I could even attempt it, let alone actually finish.
For the diy option instead of a load cell you can just use a digital kitchen scale. I think you have an excellent point about the efficiency, it's difficult to balance thrust/load and electrical efficiency/battery life to achieve an optimal time of flight. Which is why most drones can't fly for very long.
A lot of info, amazing explanation & awesome video
Thanks Scott :)
My pleasure!
Hello, congratulations for the video, very interesting to be able to measure the thrust of the engines myself.
But a big problem I have is the balance of the propellers, of course I'll still look for this channel, because now I'm another subscriber.
Thanks.
sorry for my english (google translation) :)
Indeed quad copters/ drones is a very interesting subject and has seen big developments in recent years and definitely will continue to evolve. Its also true that the market is flooded with prebuild drones, separate components and can be overwhelming at first to figure out a dyi setup. I believe the folks that do racing drones and have more practical experience can be a great source of information, maybe consider a colab with a fellow youtuber or visit a local drone club and make new friends. Maybe try not to overthink it and just for it. Either way will be here supporting your progress
Echt cooles video mit viel Infos. Vielen Dank
Excellent handwriting!!
I think while adding the bullet propellor connectros, the propellor should be added first before adding the balancing nut like part, then adding all , it will self centre the propellor.. more stability,
Great video btw
Thanks for the tip :-)
i find ecalc works wonderfully, its super cheap and makes for a great way to know all of the technical flight characteristics before buying a single component. all my drones are from scratch and worked perfectly the first time. cheers
Hey Scott! Sensors based on strain require that all deformation of the system happens in the loadcell (an ideal scenario) so other components don't absorb a small amount of the load thus reading the correct load intensity being applied.
To improve your DIY measurements you must lower the distance between your fixed base - moving the clamp close as possible to the load cell, lowering the lever arm and the bending momentum - and the engine's base (also the height is a point to improve). Also, using plastic and aluminum for the engine's base and load cell fixpoint is not a good choice because they have the same or lower Young's modulus than the load cell material, and thus a lower stiffness (discarding the shape factor). It's a good practice to choose components for these parts whose stiffness is as triple as the load cell to contain the deformation in those parts (and/or change the component material). In a practical application, loadcell from aluminum and other components from steel is a good start before changing its shape.
And last, but not least, avoid all kinds of play (backlash) in your system.
Hope you find those tips useful and have fun!
I feel that a super easy (I don't need 3d printers, or speciality load sensors) DIY solution to test would be simply to attach a motor (with blade of course) to a mass that is too heavy for it to lift, put it on a scale, use some sort of shield with a small hole in the center to allow the motor to pass (this to make sure the downward air doesn't affect the scale) and simply measure what the mass difference is to figure out lift at various voltages. You wouldn't even need a particular high resolution scale either as I doubt you'd need to know the difference down to even the hundredth of a gram
Yup, this works great. I used it when tuning my own years ago. The only challenge is that you want to avoid ground effect. To do this, I made a stand with a flat base and a piece of wood about one foot tall, then mounted the motor on top of this. The stand then sits on top of the scale. The stand also provides the added weight (and a surface for more weight) to keep it from flying away.
@@reverse_engineered i created a similar stand, i basically put a weight scale on the ground, put a motor mount on some barbecue sticks on top of the scale and ran the prop in push configuration =
weight=lift
I have built hundreds of drones from tiny 2" propped quads, up to 30" props and octo rigs for cinema use. You are going about this incorrectly, you can't pick motors and props first like this. You probably won't get off the ground currently because with 4 motors at max thrust making 1.6kg of thrust, your whole drone (drone, batteries, payload) should only weigh between 4-500g which is nothing. Don't use 3S, that is your biggest mistake, you need a higher voltage, 4-6S depending on KV rating, with higher voltages being more efficient. Roughly, 1000-1800kv you want 6S, 1600-2200kv would be 5S, 2000-2700kv would be good with 4S. Less blades are more efficient, more blades give more thrust. Those RS2205 2300kv on 4S with a 5x4 triple blade prop should make about 1kg max thrust each, making your take off weight ~1kg. Those are race motors so battery life won't be the best, especially if you fly it hard. The lighter the drone and payload the more battery you can add for additional flight time. From experience I can tell you it's possible to get 18mins flight time with similar motors and flying gingerly. I don't want to give you the answers, but you need some guidance in the right direction based on this video.
A question.. What would happened to a 2000-2700kv motor in 6s? Considering “its rated for 4S”
Also some years ago we were building an RC plane, with no idea about motors n voltage ratings.. we failed😞 ..
@@merxellus1456 TL;DR - Toast the motor. Higher KV, lower voltage, higher current, turns faster, not as torquey, small props. Lower KV, higher voltage, lower current, turns slower, more torque, bigger props.
You'll toast the motor if it can't handle it, some motors will tolerate it, with enough cooling, there are racers that definitely run high KV motors on higher cell counts, but this is a general rule of thumb when picking voltages and KV ratings. If you have a motor and lets say the impedance of its windings are 10ohms, on a fully charged 4s, that's 16.8v, the winding will draw about 1.7A, and this is about 28W of power. If you run it on 6S, that's 25.2v, that same winding draws about 2.6A, but now the motor wattage is 63W, over double before, some power always gets dissipated as heat, heat is bad, especially if it melts the insulating coating on the windings because then you get shorts, allowing more current to flow, leading to more heat, etc, and the motor burns up. Now KV rating is a rating for rpm, its almost better written as rpm/v because for every volt of your battery, you motor will spin the KV rating (it will usually never actually reach this due to drag from the prop but it gives an idea. An example 2000kv motor will spin at ~30k rpm on 4S at full throttle. But why can lower KV motors run higher voltages? Well a lower KV motor has more wraps for its windings, and of thinner wire, this means its impedance is higher and less current flow then a higher KV motor, meaning you can run more voltage while keeping current and the power going through the motor lower then that same voltage for a higher KV motor. Additionally, lower KV motors produce higher torque and thus can swing a bigger prop, but they do so slower, which is fine because larger props produce more lift and don't need to turn as fast.
@@merxellus1456 I run 6s on 2200kv motors. 5.1x3.5-ish props (my favorite so far is HQ R38’s) and my racing frame screams!
@@KlockworXMusic you have a very ignorant understanding of how motors work. increasing the voltage does nothing, as the overall power is still the same. you are pulling less amps, but through smaller diameter wires. the overall loss is the same.
"lower kv motors produce higher torque" that's only true for a given amperage and everything else being equal. in reality, torque is not constant and is dependent upon many other factors. a motor will draw more current to produce the equivalent amount of torque if it needs to.
@@Blox117 I am not sure the best place to start with this, but I think I can see where you are making a oversight. Voltage 100% makes a difference. What you are referring to is for the same motor, at the same RPM, it will draw the same amount of power on either voltage, drawing less current on higher voltage. However this is only true up to the max of the lower voltage, at 100% throttle on a lower voltage it will draw less power then 100% throttle on a higher voltage. An example of this can be seen in this chart, where the same motor with the same prop (TMotor 10x3.3 CF) is run on 3S and 4S voltages. Notice the motor draws double the wattage on 4S compared to 3S.
uav.jreyn.net/user/pages/04.quadcopter-design/step-5-motor-selection/20131024034814598.jpg
Also I don't know where you are getting that somehow the motor wires magically get thinner when you plug a higher voltage battery in, but plugging in higher voltages does not magically make your motors wires thinner. If you have 2 motors, completely identical except for the KV value, their max torque will be the same. Lower KV motors generate more torque then a higher KV motor, at the same amperage. However if it take 10A for the lower KV motor to produce that torque vs 100A for the higher KV, the lower KV is more practical in producing that torque. 20A ESCs are cheaper, lighter, and more widely available then 200A ESCs, and you can run thinner, lighter wiring as well. Additionally if that higher KV motor max amp rating is say 90A and its trying to pull 100A, its not going to be happy. The other problem running a large prop on a higher KV motor can cause tip speed to become too high. Tip speed should be below 0.9 mach at a maximum or you will start to get vibrations and inefficiency, but ideally you want tip speed at or below 0.6 mach to keep noise to a minimum. Props size and motor speed should be matched to some degree.
My comment wasn't supposed to be a perfect explanation, its supposed to give a general guideline for someone who is new how to more effectively pick a motor without going way into depth, because you can build your first drone without crunching every number and looking at it from every angle, but if you want to be a snide dickhead on the internet, you do you.
my son surprisingly bought me a Snaptain SP510 for a present a year or 2 ago, HUGEEE leap over cheap toylike drones
Nice timing, I'm currently designing my own motor / prop test stand to measure thrust and current flow
Perfect!
@@greatscottlab Motor manufacturers have listed specifications including a chart showing thrust, current draw, efficiency(g/w) RPM(often at 50% and 100% throttle) for a given series of prop sizes and voltages thereby eliminating the need for this experiment.
Great video nonetheless
Interesting video. Can’t wait for your drone video!
Thank you for the video, why not comparing with the motor datasheet ? Motor drone company usually send best configuration motor+propeller with the associated thrust and current consumption.
With my experince, it's best to get the total weight of the drone, then appropriately size the motors and the props to provide enough thrust at 50% power to keep the drone airborn. It is a balancing act between the props, motors and the battery.
Should also run the same tests with the sort of voltage you get with a depleted battery as well.
Need to know how reduced the thrust/RPM is on low battery, so you can still fly the drone to somewhere safe.
I'll tell you the result would be much similar to reduced thrust/lift on low fuel tank in any chopper/plane. They fall down.
Waited for this video for a long time :)
I remember tweeting at you recently about this and I'm sorry for the pressure! :)
Do either testing stand eliminate force from the motor turning through the air?
I.e. if we replaced the thrust propeller with a centrifugal impeller
love the bill cypher on your shirt
An important thing to consider with the thrust test is the voltage, as I realized myself. The battery does not have a constant voltage throughout its discharge cycle, and while current is drawn the battery voltage is again lower. Therefore I recommend to make the tests with the power supply voltage of around 3.5 V per cell, so that your setup has still enough power to lift itself up when the batteries are depleted.
Lower KV motors produce less RPM but more torque so you can spin a bigger prop with it hence creating more thrust at a lower RPM
I'm excited and waiting....
Sometimes the DIY or BUY question is easy to answer.
An old Dutch saying "Het bezit van de zaak is het eind van het vermaak" (owning it ends the joy) explains it all. For me the journey is the destination: It is the technical challenge of building an programming a drone that I like but I don't see myself flying drones as a hobby.
How’s everyting going?~ GreatScott!-Yeah~ best job~
Two years ago I was trying to build a quadcopter using Arduino. I bought everything and I tried every component separately, all of them were working how they were supposed to be. I wrote a part of code just for auto-leveling, and build a test setup that ensures a safe code test platform. I used a Wi-Fi module to send data to my computer for debugging. When motors were off, the sensors were recording data correctly no matter how fast I turn the drone with my hands. But, once the motors start to run I was seeing a 15 deg error in the axis. Then I gave up and just bought a controller. Even though I failed, I learned many things from that experience.
I like this video but one thing to note is that sometimes troubleshooting problems like this by failing is a very beneficial thing. I find that fixing the problem and tinkering with things is the best way to learn. Of course, this doesn't mean tinkering with stuff like high voltage or Teslas/high voltage electronics without learning how to handle them (for that I will want to definetely want to watch tutorials on before I start tinkering). Also, you need to have the appropriate insulated tools, gloves and rated multimeters but you get the idea. For projects like drone building, it's definetely a lot of failing before you finally get it to fly.
Instead of using a load cell could you not just use a set of digital scales and a motor holder attached to a pivoting arm so that when lift is generated it pushes down on the scales. Then run at 10% power increments and plot a graph from the readout on the scale after accounting for the force from leverage.
A digital scale is (one or more) load cell(s).
Thats why u get a stack or a 4in 1 esc/frightconrroller combo
This channel is great
Awesome video.
Just as I ordered my 1st starter drone after nights of considering DIY drone based on Raspberry Pi 3 or a pre-build drone, this video is finally here.
I hope my video helped a bit :-)
Hey scott thr greatest!
Please can you make a video about how being organized as you?
a lot of manufactures include a pdf in their website showing thrust and energy consumption with a specific ESC/PROP combo
Great vdo....hey GreatScott could u make a vdo on dc bidirectional H- bridge mosfet motor driver
Most manufacturers will give you information about what propeller to use,and how much thrust that will generate. You want a minimum 4:1 thrust weight ratio for cinematic flying.
Race drones have 8:1 or above.
Very good 👏
It would be interesting to test a newer 32bit esc or one running Bluejay firmware, you can change the firing frequency and have a fancy tune play when you switch it on
I was wondering. Next time why not try a DoE (Design of experiment) approach to analyse the data by Anova and get a response surface. With so many variables to test you reduce the number of experiments and get a beautiful graph :)!
I will see what I can do ;-)
@@greatscottlab Great! If necessary, don't hesitate
The 2205 2200 KV motors are perfect for a light 5 inch freestyle setup with 4S 1300mAh 75C battery. this is very fun to fly but it has a lot of power, so some training might be needed - uncrashed is a current good sim. tri-blades have better grip good for freestyle, two blades are more efficient good for longrange. ESCs with Blheli_s (there is open source firmware, bluejay) should be used, ESC tech has changed slightly. Flight controller Betaflight comes on most F4 or F7 based boards. If you want it to fly waypoints you can flash INAV. If you need more help just ask me, drones are easy.
In the mid 2000’s I measured thrust values in university. Our thrust test stand measured force by pushing down on a simple electronic scale. Tare the weight of the rig and you get a nice easy to read value with an instrument you probably already have. Manual reading though, the load cell would be much easier to automate.
could also use a balance
Cool Video 👍
Your Videos are so much more interesting than my homework i should do 😂
And you learn something with them as well ;-)
YOU FEATURED ME ON THE STARTING COMMENTS!!!!! :D
YOU MADE MY DAY
You can load the low rpm/v motor with a much larger propeller, at lower voltages and skyrocket the efficiency...
Hi Scott, I was wondering if you could do a DIY or Buy for an automatic switch reverse UPS for solar power?
I was thinking if trying to use my solar battery for appliances in my home, but have an automatic switch to cutover to AC once the battery voltage hits a minimum voltage that can be set.
I have seen a commercial version called the ATS-11KW, but that seems like a lot for the function.
amazing channel!! great video ⚙️🔧😍😍
Thank you 👍
Danke!
Thanks for the support :-)
Which one is more efficient? As always fixed wing.
Lower kV motors should be used with larger propellers, best thing to do is check the manufacturers data sheet.
I suppose the whole testing setup is not required when you have the data sheet and it's free.
Best of luck for the build!
You are testing at zerro airspeed, which is only good for hovering. Maybe good to just go fly, try different configurations, see what works best.
Thanks!
Thanks for the support :-)
Just build a little cart with motor mount and hook it to a luggage scale that is fixed on your table.
That's the way we always tested our motor/prop combo.
Read the scale and you know directly what it will lift.
HI I AM A BIG FAN
THANK YOU FOR YOUR AMAZING VIDEOS
You are welcome :-)
New intro is so cool
Among the parameters and hopefully you may talk about, was the C rating of the battery.
If it flies, you're having fun. I appreciate the amount of research you're doing but it's all been done already by countless channels before. Slap together a 7" "long range" type build and send it. I'm sure you've already found Joshua Bardwell and his massive catalog of videos. Pick a build and copy it.
I use a laboratory scale and Excel. It works. I think a good kitchen scale works as well.
The sequel we've been waiting for
I hope you liked it :-)
Thanks for teaching us! Would the plastic DIY 3DP motor mount have a tiny amount of flex in it that would effect the force readings? Meaning, a metal DIY mount solution might be better?
While flex coul potntially affect the reaing if it is poorly mounted in ege cases but generally it won't. It could be mounte to jelly and ultimately the same force gets applied to the sesnsor.
It would be interesting to test a newer 32bit esc or one running Bluejay firmware, you can change the firing frequency and have a fancy tune play when you switch it on
I dont know how are u controlling output signal here I mean how u control thrust so engine is spinning faster and slower?
Remember with multirotors it is best to have thrust at 2 x weight, I think it is 1.5 x weight minimum.
Yup, that's about what I would recommend too. 1.5x weight is okay for slow, gentle flights, but 2-3x weight will allow for much more aggressive acceleration (including changing direction) without losing control.
Hey Scott!
Idea for a DIY or buy episode:
Try to make your own Car-Bluetooth-FM-Transmitter. Those things are widely available yet most of them still fail to produce a decent result. I can imagine it's probably quite easy to build your own or maybe even better upgrade your bought one with other components.
He has already made that.
th-cam.com/video/khXwzBW2sHI/w-d-xo.htmlsi=Eba-zuzNrdODWx3A
Man, the colour on this video is nice. Are you colouring grading differently?
Is it possible to use the buy option software with the DIY version?
Oh, oh.. I'm a quadcopter enthusiast, professional technician and test-pilot for drones! As well as a techie guy so hey - this sounds super interesting although I don't assume there's anything I could learn ftrom you about drone-flight itself I'm craving for all the background knowledge you're gonna give! ;)
Thanks and Cheers!