My new thrust test stand had quite a good workout yesterday😊
I have also created a new test spreadsheet which will be streamlined and focus more on motors that I currently might use in my park jets. I changed things up a bit, when you click on the words "new test spreadsheet" above it will take you to the spreadsheet which I created in Google Drive. I added columns for battery voltage before testing and after 50% throttle test and 100% throttle test. rcplanepirate RCPP and I have discussed this variable off and on in our discussions, so I decided to add it in to see what is happening with the batteries I use for testing.
I kept the 50% throttle test in to allow me to see what is going on in the mid throttle range, I let the motor run for about 5 seconds at 50% throttle, this also allows the thrust to "stabilize" a bit more at that throttle setting and I suppose represents launching the plane and getting established before making the first "speed run" at 100% throttle where I also hold the throttle for 5 seconds to allow the thrust to stabilize.
I tested seven motors yesterday, the swapping of motors once I got the hang of it wasn't as much of a pain as I first thought it might be in my initial impressions post about my new thrust stand. I'm not going to worry about comparing numbers to my old thrust test setup at this point, suffice it to say, those old numbers were quite inaccurate, especially at full throttle, so this is a bit of a "do over" on some of the motors.😏
I tested the 2212/6 2200 Kv motor as a bit of a benchmark, and also to compare the three different brands of batteries I currently use, you can see the results on the first page of the spreadsheet. I will continue to fill that in as I retest this "workhorse" motor with a wider variety of props.
For the new tests on the quad racing motors, I used my new Gens Ace 2200 3S 45C batteries to give them a bit of a workout and get a couple charge cycles through them. I also grouped the quad racing motors in those that are 2700 Kv and above, and those that are less than 2700 Kv, you will not they have their own page on the spreadsheet to make it easier to compare them.
These are the numbers for each quad racing motor at 100% throttle with the 6x4 APC gas prop using the Gens Ace battery to allow for a bit of discussion/comparison. A few of these motors had not been bench tested before as I was waiting for the thrust stand to arrive.
Quad motors of 2700 Kv and above
- EMAX RS2306 2750 Kv - 38.1A/434.7W producing 1088 gr/38.4 oz of thrust;
- BeeRotor Z2207 2780 Kv - 34.9A/422.4W producing 1095 gr/38.6 oz of thrust;
- BrotherHobby Returner R2 2205 2800 Kv - 33.9A/389.7W producing 1017 gr/35.9 oz of thrust;
- Racerstar BR2306S 2700 Kv - 31.8A/369.0W producing 998 gr/35.2 oz of thrust;
- Foxeer DATURA X2206 2700 Kv (still waiting to be field tested) - 38.4A/459.2W producing 1062 gr/37.5 oz of thrust.
Quad motor below 2700 Kv
I only tested one motor below 2700 Kv, my favorite of this group thus far😊
Racerstar BR2406S 2600 Kv - 31.7A/385.7W producing 982 gr/34.6 oz of thrust.
The EMAX and BeeRotor motors are very close in top end thrust, but this does make a bit more sense when after reading the results on www.miniquadtestbench.com they are both actually 2630 Kv motors. However, after looking at their respective mid range numbers, it helps me understand a bit better why I gave the edge at the field to the EMAX motor.
EMAX at 50% throttle - 16.9A/204.7W producing 642 gr/22.6 oz of thrust;
BeeRotor at 50% throttle - 15A/181.5W producing 598 gr/21.1 oz of thrust.
Of course the EMAX motor eats up quite a few more amps to produce this power, but this makes more sense now about the slight edge in performance in the air.
The Foxeer DATURA looks like it has serious potential to be a real powerhouse for such a light motor even though it too is a bit "amp hungry", I'm excited to field test that next.
Just basing it on the numbers, the two Racerstar motors are quite a bit closer in bench performance than I expected. Based on how I saw it spin up on the thrust stand, the BR2406S 2600 still has the most low end torque of all the quad racing motors I have tested thus far, that slightly bigger stator and bell size do seem to make a noticeable difference.
Thus far I'm pleased with how this new thrust stand is working out, much easier to get things set up and collect the data than perhaps I initially expected. Much more testing to come in the coming weeks as new motors arrive and I evaluate different props with each motor😊
Park Jet noise...the "other" sound of freedom😎
Cheers,
Scott
Hi Scott,
ReplyDeleteGreat to see the test stand operational! ������������
Very interesting discovery with the 50% comparison, especially with the emax and bee motors. Seemed to have confirmed your observation with inflight tests.
With this in mind, is it better to ...
1) Initially bench test the motor only at 100%, fly it and observe, then perform all bench test?
2) or...perform all bench tests, then fly?
Just wondering if performing all the bench tests prior to flight would introduce a bias to the flight observations?
In any event, fantastic work and looks like you’re providing data driven results (bench and flight) with this hybrid use of motors, and having FUN in the process!
Thanks for posting!
Jim
Hi Jim -
DeleteThanks very much :)
Great question, I suppose it depends on personal choice or the situation. Even if you test a motor with the same setup as someone else, you might get noticeably different results for a few reasons
- as I found out myself, quality or setup of the test rig :/;
- quality control of the motor/ESC/battery;
- age of the battery. In discussion with RCPP, after a battery has perhaps about 100 cycles on it, it might still be good for flying, but might not deliver the goods for a valid motor test;
- temperature and atmospheric conditions can also impact performance. Having said that, I don't think that unless you are in the high Rockies or the Himalayas that you need to worry too much about whether your prop, motor, ESC and battery are going to work together OK, but it will make a difference.
If you have some data already that you trust either from the vendor/manufacturer or someone who has done some testing, you can go to the field and just see what happens and then bench test it. Having said that, a quick test with a wattmeter will let you know if your ESC and battery will be up to the task of your particular prop and motor without knowing how much thrust they produce. This is just kind of a safety check to make sure you didn't get a 2700 Kv motor that was labelled as a 2200 motor or something weird like that :) When dealing with some of the cheaper Chinese motors, this is very possible, so it is a good idea to have a quick check with the wattmeter to ensure you don't overheat anything and lose your plane.
If you are venturing into uncharted territory with a motor you can't find any specs on or want to use a prop that hasn't been tested before, then definitely it is a good idea to bench test before field testing. This will tell you if the motor can actually handle the prop based on heat buildup or amp draw (if you know the amp limit of the motor) as well as what ESC and battery you need to use to ensure you can safely deliver the amps that the motor wants.
In my experience, having a plane designated as a "test bed" also take some of the guess work out of it when doing field evaluations. That way, there is one more factor of consistency added in. I find choosing a plane that you are comfortable flying, not necessarily the fastest is a good choice. Then you don't have to focus as much on flying the plane and can pay closer attention to what the power setup is doing.
Just my thoughts and experience anyway. When I first started playing around with props and motors and testing them, I did most of it at the field first and then tested on the crude bench setup I used to use.
Cheers,
Scott
Great information on these motors. I usually buy budget motors so it's nice to see those test. I'm guessing one of the biggest difference between the budget motors and the higher dollar motors will be the consistency of the quality of the motor. If that's the case, the test will show that over time or perhaps the budget motors will close that gap a bit. Thanks for all the motor test and Happy Flying!
ReplyDeleteThanks very much :) I think using budget quad racing motors in park jets or other fixed wing airplanes will help contribute to their longevity somewhat. I know from watching several discussions on YT from fellows who race quads that crash durability might be more important on a quad, perhaps not as important on a plane. Of interest, when I watched this video, since the magnets on most of the budget motors aren't as strong, they don't lose their strength as quickly and might last longer over time? https://www.youtube.com/watch?v=WtQYDsH3Cgk&list=PLKu3yFqYM98mK5QwETbUPR9Us4IREHi3y&index=14 Thanks again and happy flying to you as well :)
DeleteCheers,
Scott