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Dec 10, 2008, 10:49 AM
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Motor Data - test bench data for several hundred brushless motors.

For many years several of us have been generating and accumulating test stand data for a wide variety of electric RC motors, but the information could only be found, frustratingly scattered, amongst a myriad of threads in RC Groups.

Now Robert Goble has taken it upon himself to set up and maintain a webpage which provides a central, searchable source for all the available data: anyone with reliable test data is invited to contribute their information to the cause! . Update: 3.12.14: 608 motors.

Welcome to

Mission Statement:
To standardize brushless motor measurements in a comprehensible way, and to provide radio controlled aircraft pilots with a common resource for comparing and choosing the right motor for their applications.

At this time, we are obviously still adding to/proof reading the data sets, so bear with us. Much of the data posted so far is from my own testing [any and all errors are mine alone], but obviously lots of other people will add their data as this site evolves.

As far as my own data are concerned let me add a caveat to the way in which parameters such as Io have been measured, and Kv and Rm have been calculated - I run no-load and prop tests on each motor... I measure Io/rpm at several voltages but typically have entered the figure I obtained @ ~10v into this database [manufacturers, if they give you an Io, usually do not state the voltage at which their Io figure was obtained]. I then use a program such as Motocalc or Drive Calc. to calculate Kv and Rm. I cannot see that there can be much argument over Kv (even though there are occasionally great disparities between my figures and those posted by manufacturers - where do they get some of their numbers? - no-load rpm divided by voltage applied is a reliable guide to at least a ballpark figure). For Rm, I find that often my figures differ substantially from those given by manufacturers and distributors - they may be using Rm for one phase (I know Mega does that), or Rm for the motor directly, when, in my case, an ESC has to be in the system. Any suggestions as to obtaining the most accurate figures are welcomed.

There is now an advanced search function:

We hope that this resource proves to be useful.

Update 8.17.12: It would seem to be useful to document my test procedures, so that anyone who wishes to can (a) see how I get the results I get and more importantly (b) repeat my tests to see whether in fact I have got the right answers!

Refining the Test Stand procedure
Those of you who spend any time in this forum know that I test a lot of motors using a standardized test regime. In applying the "Scientific Method" and using the same equipment each time is, to my mind, the only way to get consistent and repeatable results.

I use my Dr Kiwi Mk II pusher stand, with an Ohaus CS2000 or CS5000 Digital scale, a Zurich DS-304M 0v-15v/25A power supply, a Medusa Analyzer Plus meter, a Hobbico Digital Mini-Tach, a Raytek IR temperature gun and an Esky Servo Tester. When current demands exceed the Zurich's ability to supply, I use a variety of Lipo packs... Gemini 2s 4000 and 3s 4000, Enerland 2s 5400 and 3s 6000, TP Prolite 3s2p 4200, and Evo 4s 2150 packs.

Through the generosity of Bill Parry at Eagle Tree, I have an Eagle Tree v4 Logger with a Power Panel LCD, and temperature and rpm probes. I have modified the RPM probe by soldering two different sizes of brass washer to the input lead….these washers are slid over/between male and female connectors on one of the ESC-motor leads….one washer suits 1.8mm-2mm connectors, the other works for 3mm-4mm connectors. I have modified the temperature probe by enclosing the thermistor with a brass sleeve, drilled to accept 3mm mount screws, so that it can be attached to a motor or mount, rather than trying to jam the thermistor itself into the windings.

My usual test regime is to first record the motor temperature (from the windings, with the IR Gun), then run each motor/prop combination to WOT at incremental voltages as set on the PS - 7v, 8v, 9v, 10v, 11v - (sometimes 7.4v or 14.7v - the max. for the Zurich), for just long enough in each burst to write down volts, amps, watts, thrust (g) and rpm. For each burst to WOT, I can manage to record all these parameters within about 10-15 seconds, so that means that an entire series at five different voltages has the motor running for only about a minute, total. At the end of such a series, I'll record the motor temperature, with the IR Gun, usually directly from the exposed windings. Using the v4, I record the initial temperature, then record the temperature on the PowerPanel at the moment I stop the run… then I wait, usually for 30 seconds or so, for the temperature shown on the PowerPanel to reach a peak and record that. If it gets too hot (>50C - 60C) after this standard series, then I reckon the motor is not going to cope too well in real life [in-flight cooling, unloading and all that stuff not withstanding]. I usually mount test motors using aluminum stick mounts, so, with the temperature probe attached to a mounting screw, from the v4 probe, I can get an idea of case temperature during and after the run.

Invariably, once I've tested a motor or a series of motors I'll post the results as a Mini-review in the Power Systems Forum of RC Groups. As far as the Data Tables go [see SunnySky X2212-6 (~1950Kv) below, as a typical example], the headings contain the basic information about the motor and ESC and date of testing. The no-load data is obtained using the Eagle Tree v4… measuring amps and RPM with voltage set at 7.0v, 8.0v, 10.0v as shown on the Medusa Analyzer Plus. Once I have collated the data, I use DriveCalc to compute Kv and the efficiencies at certain amp draws. Most of the columns are self-explanatory… pitch speed is simply a function of the RPM and the pitch printed on the prop, nothing more! The last column of “RPM as a % of Kv x V”, which is intended to give an idea of loading (or over-loading!) with each test prop, is derived using this DriveCalc computed Kv, not the “raw Kv” which would be obtained from, say, the measured no-load RPM @ 7v, 8v or 10v.

On the left side of the tables, the initial motor temperature is shown (from IR reading)…then beside the final voltage (usually 11v) the total number of mAh used during the series is given, along with the final motor temperature (from IR again). The v3/v4 temperature readings given, are, as explained in the heading, “Initial (black)…. End of run (blue)….Maximum, prior to eventual cooling (red)”.

Cheers, Phil

Most recently (September, 2013) I have acquired a second temperature probe which can be inserted directly into the windings of an outrunner. My Tables within MiniReviews may indicate read-outs from Temperature probes A and B.
Last edited by Dr Kiwi; Mar 12, 2014 at 11:34 AM.
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Dec 10, 2008, 11:26 AM
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rgoble's Avatar
If you have any questions or problems with the site please let me know here.

Also if you have any ideas for improvements I would be glad to hear them.
Last edited by rgoble; Dec 10, 2008 at 12:00 PM.
Dec 10, 2008, 11:38 AM
characters welcome!
Mark Wood's Avatar
Originally Posted by Dr Kiwi
P.S. How does one make this post into a "Sticky". Is that a good idea?
Already did!
For future information, you request a sticky using the Report Post To Moderator button and choose Stick/Unstick thread option.

Dec 10, 2008, 04:30 PM
I steer with my thumbs
CuStOm's Avatar
Awesome! Thanks for sharing all your hard work!
Dec 10, 2008, 04:43 PM
Good Better Best quest.
olmod's Avatar
Great only suggestion i can make is to give the vertical columns colours ,as i work my way down i lose whats amps ect.
but a worthwhile data base IMHO.
Dec 10, 2008, 08:37 PM
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rgoble's Avatar
Thanks for the suggestion. I added a new header row that shows what the columns are ever 30 rows. That's about one every screen (at least for my resolution) and can be adjusted if needed. I was going to use the column colors as you suggested but I think this might work better.

I never realized the full extent of testing Phil did on these motors until I started adding his data to the site.

Dec 10, 2008, 08:40 PM
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lake flyer's Avatar
I registered , but did not get my confirmation email ??
Dec 10, 2008, 08:46 PM
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rgoble's Avatar
I'm not sure what happened there. I sent you a pm to verify your email address and I activated your account.

Dec 10, 2008, 09:16 PM
homo ludens modellisticus
Ron van Sommeren's Avatar
Add these measurements too?

Vriendelijke groeten Ron
Dec 10, 2008, 09:22 PM
Registered User
rgoble's Avatar
Is that your site or does it belong to someone else? I don't want to add someone's data with out their permission.

Dec 10, 2008, 09:31 PM
homo ludens modellisticus
Ron van Sommeren's Avatar
It's not my site Robert, you have to contact Fredrik.
Dec 10, 2008, 09:42 PM
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rgoble's Avatar
I just emailed Fredrik, I will have to wait and see what he says. Thanks for letting me know about it.

Dec 11, 2008, 07:28 AM
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Dr Kiwi's Avatar
I'm through all the entered motors.

For some of the motors I tested early on, I did not obtain no-load data... for those I still have, I will, in due time, measure those parameters. For other motors we may have to enter, in the interim, "manufacturer's data" which is a problem since we have no way of knowing how their figures were obtained - hopefully users may be able to contribute measured numbers for some of these. If you don't see a "Dr Kiwi Io data" entry, then you'll know that the Io and Rm are from some other source.

For some motors I did not measure diameter and length [contributions please!] - we could use manufacturers' figures, but these require caution since some include the entire shaft in the "length" measurement (some only give stator length, and some are pure fiction!)... I have consistently used "body" length (end plate to end plate, or front face to rear of bell), since I think that gives the user a better idea of the physical size of the motor.

For shaft size I have simply entered the nominal sizes (2.0mm, 3.0mm, 3.17mm, 4.0mm, 5.0mm) although every shaft is different (usually smaller by a few hundredths of a mm).

Cheers, Phil
Last edited by Dr Kiwi; Dec 11, 2008 at 04:27 PM.
Dec 11, 2008, 05:06 PM
Flying motor mount master
fly_boy99's Avatar
Great job Phil, this will be an invaluable resource for many folks who come to RCG for answers.

Now one question that comes to mind is watt rating. Are you guys just going to stick with the manufacturers recommendations or go with what people are flying at today?

Again, great job!
Dec 11, 2008, 05:18 PM
I steer with my thumbs
CuStOm's Avatar
The weights on the motors seem to be wrong when compared to Phils spreadsheet.

Look at the Suppo's......

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