Many people have requested me tips on how to properly dimension your motors to your quad. Especially today, when we have a ton of accessible motor choices. The following gadgets shold be considered when deciding on the suitable motor on your racing drone or multi rotor:
Step 1. Choose Frame sort
Your frame type will decide many components about your drone, corresponding to what dimension props you probably can run, and what measurement motor you’ll be able to mount.
The motor measurement that you need to select is essentially dictated by the dimensions of your drone or quadcopter. Therefore, the first thing to consider when choosing the right setup is to find out what measurement drone you wish to you wish to construct, what dimension props your chosen frame can run, and what batteries you want to use. Are you building a racing drone? Freestyle acro flyer? Or are you constructing one thing to haul a digicam and get one of the best flight time possible?
There are a quantity of types of motors obtainable and a number of other Stator/KV combos out there. The aim is to construct a balanced, properly engineered system which compliments your flying fashion, the aim of the drone, and the drone dimension.
By correctly sizing your motor you will get longer flight instances, longer gear instances, much less put on and tear, and lower temperatures.
Step 2. Determine the prop size that your drone will run.
Your prop dimension might be decided by your body. So should you select a QQ190 as an example, you could run 5″, or 4″ props, but for this example, we are going to select to run 5″ props not only as a outcome of that is what the QQ190 was designed to use, but also because this is the largest dimension that we’ll be working on our construct.
Step 3. Choose your stator dimension
A basic rule of thumb is to categorise your motors first by stator dimension after which lastly by KV after other elements have been thought of.
We right here at QQ have discovered the next to be an excellent beginning information for sizing stators to propeller measurement:
Approx diameterQQ Frame SizeProp SizeRecommended stator sizeLowest kv recommendedHighest kv recommended150mm & smallerQQ1303” mmQQ1664” mmQQ190, Sparrow R2205” mmQQ2206” mmTBS Vendetta7” mmTBS Discovery8” mm & largerTBS Discovery9” Step 4. Determine the essential factors for your build.
Selecting the right motor comes all the method down to weight, energy, effectivity and torque and the importance of every of these are in the end determined by your flying fashion and what you are trying to accomplish together with your multi-rotor build. Ideally, you wish to attempt to engineer your quad to effectively fly, but additionally generate enough thrust with out completely destroying your battery. You additionally need to construct your quad for your flying style. An all-out drag racer goes to have a different perfect motor than a freestyle quad. A motor with a larger stator may also be heavier, and could have a slower response time because of the moment of inertia. So ideally, you must have the ability to select a motor that is environment friendly, doesn’t draw too many amps, isn’t too heavy, and has the facility to get the job carried out.
Wept- Weight, Efficiency, Power, Torque
A good pnunomic to recollect is Wept- the guys that didn’t choose the correct motor for their quad construct wept as a end result of they cooked their batteries.
The common concept that you need to adhere to is ordering the next weight efficiency power, and torque in terms of priority on your particular person construct and flying style. Once this priority has been made, discovering your perfect motor ought to be simple.
A lighter motor goes to have a quicker spin-up & slow down, and will yield a quicker change in pace.
A heavier motor will take longer to spin up and decelerate, and will yield a slower change in pace.
A lighter motor will most probably really feel extra exact within the air, and pids might be easier to tune.
lighter motors are extra prone to wreck upon impression, so beginners might be better off with heavier motors.
If you’re doing more straight line racing, a heavier motor might be higher, nevertheless, if you are doing plenty of acrobatics & aerial stunts, go for a lighter motor.
The highest performing quads have the best energy to weight ratios. Motors also can make up a big part of that, so hold that in mind as properly.
Efficiency is measured in grams/Watt so think of it in terms of thrust/power required.
Motor effectivity can effect flight times, voltage sag, and battery life. Ideally, you need to strive to choose the motor that is most efficient all through the vary of operation, not simply on the highest RPM.
Remember that your battery may have to have the flexibility to help no matter amp draw you’ve at WOT, and that the smaller the battery, the less capability it has to flow high currents.
A greater KV motor can are typically extra environment friendly within the high rpm ranges, however on the expense of torque.
Flying fashion additionally performs a role when choosing efficiency. For an all out, excessive budget drag racer that is at WOT the entire time, efficiency might need less of an influence in your decision, whereas if you’re trying to construct a freestyle flyer that gets nice flight time, can use cheaper batteries and decrease value escs, effectivity may have extra of an impression for you.
The thrust output of your motors has lots to do with which of them to select. Looking at all-out thrust is an effective thing to do, but it doesn’t mean every thing. A lighter quad with motors which have less thrust can feel simply pretty a lot as good within the air as a heavy quad that has motors that output max thrust. In the end, you’ll want to make certain that you have sufficient thrust to fly well. A good rule of thumb for a quadcopter is to aim for a 4:1 power to weight ratio. It is widespread to see that quantity double to eight:1 or more in racing quads.
To determine your energy to weight ratio, it would be best to calculate the max static output of the motors divided by the load of the quad. For instance, the power to weight ratio of the QQ190RTF could be calculated by taking the max thrust of the QQ kv motors with HQ5x4x3 props ( 4241.56g ) and divide by the entire weight of the quad with Tattu 4S 1300 mAh 75C battery. (471.2g). The result is a whopping 9:1 power to weight ratio. This is more than double the ability wanted for acrobatic flight and might make for a really superior flying expertise.
We could have chosen motors for the qq190RTF with a higher thrust output to go on this quad, but this wouldn’t have been a smart choice as a end result of the motors on the QQ190 only draw 24A at full thrust with HQ 5x4x3 props. This is necessary not only to maintain our special 2-in-1 ESCs happy, but also to protect the battery. By using this mixture, a C battery which can handle 97.5A is perfect for this quad. Had we used a motor that pulls more than 30A, we’d have had to redesign our ESCs, battery recommendations, and possibly the general design.
An typically overlooked and essential thing to consider when choosing motors is torque. Torque can effect the time it takes the propeller to achieve a desired pace. So a motor with higher torque shall be simpler to tune, and will make the quad feel more exact in the air. Stator measurement effects the torque output, and larger stators tend to supply extra torque, whereas smaller stators produce much less.
Advances in mulitoror motor technology corresponding to N52 magnets, curved magnets, tighter clearances, and .15mm stator laminations are allowing smaller motors to generate increasingly torque, and is one reason that we have seen a shift in racing drone efficiency in the earlier couple of years.
KV just isn’t what you suppose it is- however it’s still important.
This is where issues get somewhat bit difficult. Kv is often regarded as RPM per volt. While this is a superb method to rapidly calculate unloaded motor pace when voltage is applied, it isn’t technically the best way of thinking about it.Motor KV doesn’t let you know how highly effective the motor is, or how a lot present it could deal with, or how efficient the motor is!You have to seek out thrust tests to determine that out.
to consider KV, let’s take into consideration the basics…
When a magnet is pulled over a copper wire, electrical energy is created in the form of voltage. This signifies that when a motor spins, it creates back-emf that might be measured as voltage.
The right method to suppose about Kv is to think about it as amotor fixed. If you spin a motor, it’ll generate 1V at a sure RPM. The ensuing RPM is the Kv of that motor.
So, think of it like this:
If a motor generates 1V of back-emf at 2300 RPM, then we can determine that it’s a 2300 kv motor. If the motor were to generate 1V at 1900 RPM, then we’d be capable of decide that motor to be a 1900 kv motor.
! Remember, Kv doesn’t let you know how highly effective the motor is or how a lot current it could deal with or how environment friendly the motor is.
A small motor and an enormous motor can have the identical Kv fixed. The large motor will more than likely turn out to be extra highly effective than the small one. So there isn’t any method to make use of Kv to inform you how powerful your motor is. What Kv does do is help us to know the present requirements of a motor to supply a sure quantity of torque… as a end result of Kv is immediately associated to the torque constant.
Torque & it’s relationship to KV.
KV can help us understand the current necessities of a motor to produce a specific amount of torque…
Without going into too much detail, all that you really want to know is that the torque constant Kt is the inverse of Kv. So as Kv goes up, Kt goes down.
Torque can be calculated utilizing current and kt, the inverse of kv.
Current, torque and Kv are all associated, Lower Kv motors require much less current to spin heavy props and therefore have extra torque, however loose efficiency at excessive rpm-Vice-versa, High Kv motors require larger currents to spin heavy props, however can run at excessive rpm extra effectively.
In different words:
High kv motors require more current than decrease kv motors to supply a specific amount of torque.
Now that we know what we ought to always look for, we will start scouring the web for DATA! Google motor thrust take a look at INSERT MOTOR NAME HERE.
Props can greatly effect efficiency of your drone, and a few props are much better suited to particular builds than others. Although, beyond the scope of this post, I will solely level out that the recognition of the 5x4x3 has to do with the truth that it is a very nicely balanced prop in terms of thrust, rpm and speed. This props is perfect for freestyle flying, however isn’t fairly the quickest prop on the market, and a steep pitched, 5×4.5 bullnose prop allowed us to reach greater high speeds than the 5x4x3. For the purposes of this submit, we are going to attempt to use 5x4x3 as a result of we are theoretically building a freestyle flyer.
Pick the motor
Let’s say that we expect we wish to use the ZMX You must discover a chart of a given motor’s Volts/rpm/Watts to make correct choices about whether or not or not a motor is an effective selection for your mulitrotor construct. Without the chart, you will really be taking pictures in the dark.
Use the chart in step three to select an excellent stator dimension starting point, then find a motor that you simply assume will work. Maybe you just like the look of the ZMX Fusion Purple top kv motors. So let’s use them as an example.
Find the data
The ZMX Fusion kv has been tested in quite a few places, and it’s information may be seen right here: check out theminiquadtestbench.comfor extra knowledge.
G/WSummary Datafull throttleZMX Fusion kv100%Thrust (g)Current (A)VoltageHigh RPM PassEfficiencyProp Tested:Max(g)Avg Max(g)*Max (A)Avg Max(A)*Avg Min(V)*Max(V)MaxMinAvg Max*WattsHQProp 4x4BN .8015.5815.3716. “&R28C11, INDIRECT( RC1&”!$E$”&R28C9&”:$E$”&R28C10),” .0HQProp 4×4.5BN .3020.5514.9116. “&R28C11, INDIRECT( RC1&”!$E$”&R28C9&”:$E$”&R28C10),” .7HQProp 4x4x3BN .3018.9915.0516. “&R28C11, INDIRECT( RC1&”!$E$”&R28C9&”:$E$”&R28C10),” .9Diatone Ghost 5× .1016.9015.2216. “&R28C11, INDIRECT( RC1&”!$E$”&R28C9&”:$E$”&R28C10),” .6HQProp 5x4GF .0021.3214.8016. “&R28C11, INDIRECT( RC1&”!$E$”&R28C9&”:$E$”&R28C10),” .2GemFan 5×4.5BN .2023.3614.7116. “&R28C11, INDIRECT( RC1&”!$E$”&R28C9&”:$E$”&R28C10),” .2GemFan 5×4.6BN .9028.5414.1816. “&R28C11, INDIRECT( RC1&”!$E$”&R28C9&”:$E$”&R28C10),” .8HQProp 5x4x3GF .3025.4814.4916. “&R28C11, INDIRECT( RC1&”!$E$”&R28C9&”:$E$”&R28C10),” .1KingKong 6× .1030.2713.9816. “&R28C11, INDIRECT( RC1&”!$E$”&R28C9&”:$E$”&R28C10),” .2Interpret the info
Looking at the information, we can see that this motor with the HQ5x4x3 averages 1151g, pulls 25.48A, and has an efficiency factor of three.1
If we have a look at the identical graph, but at 50% throttle, we see that the effectivity goes means up.
G/W50% ZMX Fusion kvThrustRPMsAmpsVoltsWattsHQProp 4x4BN261″&R53C6,INDIRECT(RC1&”!$E$”&R53C4&”:$E$”&R53C5),”198155.1516.27843.1HQProp 4×4.5BN309″&R53C6,INDIRECT(RC1&”!$E$”&R53C4&”:$E$”&R53C5),”189646.1216.21993.1HQProp 4x4x3BN315″&R53C6,INDIRECT(RC1&”!$E$”&R53C4&”:$E$”&R53C5),”189636.1016.19993.2Diatone Ghost 5×3336″&R53C6,INDIRECT(RC1&”!$E$”&R53C4&”:$E$”&R53C5),”198265.2516.23854.0HQProp 5x4GF385″&R53C6,INDIRECT(RC1&”!$E$”&R53C4&”:$E$”&R53C5),”187416.2616.131013.8GemFan 5×4.5BN438″&R53C6,INDIRECT(RC1&”!$E$”&R53C4&”:$E$”&R53C5),”182866.9416.151123.9HQProp 5x4x3GF468″&R53C6,INDIRECT(RC1&”!$E$”&R53C4&”:$E$”&R53C5),”177907.5416.081213.9GemFan 5×4.6BN489″&R53C6,INDIRECT(RC1&”!$E$”&R53C4&”:$E$”&R53C5),”170948.5015.971363.6KingKong 6×4565″&R53C6,INDIRECT(RC1&”!$E$”&R53C4&”:$E$”&R53C5),”168178.7515.911394.1Compare the options
lets have a look at the zmx fusion kv blue high motor for comparability.
G/W100% throttle ZMX Fusion kvThrust (g)Current (A)VoltageHigh RPM PassEfficiencyProp Tested:Max(g)Avg Max(g)*Max (A)Avg Max(A)*Avg Min(V)*Max(V)MaxMinAvg Max*WattsHQProp 5x4GF .1024.3614.8216. “&R29C11, INDIRECT( RC1&”!$E$”&R29C9&”:$E$”&R29C10),” .1GemFan 5×4.5× .9030.5014.2416. “&R29C11, INDIRECT( RC1&”!$E$”&R29C9&”:$E$”&R29C10),” .8GemFan 5×4.5BN .4026.1014.6516. “&R29C11, INDIRECT( RC1&”!$E$”&R29C9&”:$E$”&R29C10),” .3HQProp 5x4x3GF .0030.4414.2616. “&R29C11, INDIRECT( RC1&”!$E$”&R29C9&”:$E$”&R29C10),” .0GemFan 5×4.6BN .0033.5414.0216. “&R29C11, INDIRECT( RC1&”!$E$”&R29C9&”:$E$”&R29C10),” .8KingKong 5x5x3HBN .3036.2413.8516. “&R29C11, INDIRECT( RC1&”!$E$”&R29C9&”:$E$”&R29C10),” .7DAL 5×4.5x3HBN .5033.0314.1416. “&R29C11, INDIRECT( RC1&”!$E$”&R29C9&”:$E$”&R29C10),” .0DAL 5x4x .6033.2714.1616. “&R29C11, INDIRECT( RC1&”!$E$”&R29C9&”:$E$”&R29C10),” .0HQ 6×4. .8039.2613.5416. “&R29C11, INDIRECT( RC1&”!$E$”&R29C9&”:$E$”&R29C10),” .8KingKong 6× .3036.7813.7916. “&R29C11, INDIRECT( RC1&”!$E$”&R29C9&”:$E$”&R29C10),” .2Ok, same prop, generates 1308g of thrust, but it draws 30.44A. :(. The efficiency of this motor can be a little less than the purple high KV.
Lets’s examine it at 50% throttle.
G/W50% throttle ZMX Fusion kvThrustRPMsAmpsVoltsWattsHQProp 5x4GF360″&R56C6,INDIRECT(RC1&”!$E$”&R56C4&”:$E$”&R56C5),”186775.8616.25953.8GemFan 5×4.5BN413″&R56C6,INDIRECT(RC1&”!$E$”&R56C4&”:$E$”&R56C5),”182886.5116.201053.9GemFan 5×4.5×3421″&R56C6,INDIRECT(RC1&”!$E$”&R56C4&”:$E$”&R56C5),”177667.2216.071163.6HQProp 5x4x3GF448″&R56C6,INDIRECT(RC1&”!$E$”&R56C4&”:$E$”&R56C5),”175887.4316.081193.8GemFan 5×4.6BN478″&R56C6,INDIRECT(RC1&”!$E$”&R56C4&”:$E$”&R56C5),”171038.0416.061293.7DAL 5×4.5x3HBN485″&R56C6,INDIRECT(RC1&”!$E$”&R56C4&”:$E$”&R56C5),”172308.0816.101303.7DAL 5x4x4495″&R56C6,INDIRECT(RC1&”!$E$”&R56C4&”:$E$”&R56C5),”171728.2216.111323.8KingKong 5x5x3HBN514″&R56C6,INDIRECT(RC1&”!$E$”&R56C4&”:$E$”&R56C5),”163849.0515.991453.5KingKong 6×4555″&R56C6,INDIRECT(RC1&”!$E$”&R56C4&”:$E$”&R56C5),”167958.6615.981384.0HQ 6×4.5595″&R56C6,INDIRECT(RC1&”!$E$”&R56C4&”:$E$”&R56C5),”161949.5115.901513.9So what can we be taught from this? Using the identical prop, the 2206 motor takes much more current at WOT because of the larger stator. It is also an influence hungry motor at WOT, however, as a result of the stator is bigger, it’ll have extra torque. At 50% throttle the motors each look good by method of efficiency and power consumption.
Weight wise, the 2206 weighs 30.5g vs the 2205 at 27g.
How to choose?
Both motors will work, the 2206 are an incredible motor, and so are the 2205s, partially due to the sturdy magnets. The 2206 could be a better option for pushing heavy props, however battery efficiency would be put to the test.
What it really comes right down to is private choice. I would run a gemfan bullnose with the 2206 as a result of the effectivity approaches 3.3 and the current drops to round 26A at full throttle. This would give me the greatest option whilst nonetheless offering me with the greatest torque. However, If using hqprop 5x4x3, then the purple high 2205 is a a lot better choice.
Step 6- Size your ESCs
last, but not least, use the information that you discover to just be sure you choose an ESC that may deal with the present demand that your motor/prop combination will be requiring at WOT. Give your self some room here- so if you are drawing 25A, choose a 30A esc, 18A, select a 24A esc. Your ESCs will thank you!
CW vs. CCW motors:
Q: Do I want motors with opposite threads on my counter-clockwise spinning motors?
A: No- Clockwise with locknuts are fantastic.
Some motors are labeled as CW, and CCW. What this means is that the motor nut and shaft is either handed CW (right hand thread)or CCW (left hand thread) In the early days of using prop nuts, this was extra necessary.
In our testing and experience, nevertheless, we now have found that it isn’t needed to use motors with different thread directions on racing drones and quadcopters. In theory, it makes sense to use a CCW motor on your whole proper hand motors, but in apply, a locknut does a fine job of maintaining your prop tight no matter rotation.
We have even used locknuts on 3D setups without problem.
Counterclockwise vs clockwise propnuts for multi rotors make no distinction. So why not use a motor that is cheaper, easier to produce, and easier to find substitute elements (CW motor) on all of you quads, instead of using CCW motors which complicate things?
There is plenty of hype that’s influencing folks to build quads utilizing strange component combos, and one of the best quad is one which uses components which are well engineered to work together. This is as much as you, the builder to figure out.
Find the motor testing knowledge, and let that information you thru the engineering course of. Decide your frame kind, prop size, flying style, after which use the info, your prop choice, and your personal preferences to determine one of the best motor for your build. If you still have questions, please publish them at ask.quadquestions.com in order that we might help you choose one of the best motor on your subsequent multi-rotor construct.
Remember, A good pnunomic to recollect is Wept- the blokes that adopted the hype train and didn’t properly engineer their quads wept as a end result of they cooked their batteries.