Replies to This Discussion

Permalink Reply by Greg on September 3, 2011 at 3:43pm

Good question. In the arducopter I that just crashed, I had the 5v from one ESC, but that was not the ESC the motor failed on. I had planned to change to UBEC or as Charlie suggests a good stable 5V regulator. Whislt the current Arducopter manual shows the 5v connection from one ESC via the Power Distribution board, I think this should be changed.

However its realy down to the individual, which method you choose. My goal is to eliminate as many of the single poitns of failure as I can in my quad. I should mention I did a few indoor flights, extensive electronic and programming checks before the first outdoor run. I have accepted component failures like this are expected from time to time. Hence my query about other member experience with different motors? I also plan to build a motor and ESC test harness to qualify parts going into my arducoputer.

Its a real shame I did not get at least a few flights in yesterday on such a nice Canberra spring day :-(

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DeveloperPermalink Reply by Olivier ADLER on September 3, 2011 at 4:21pm

 

Did you check the max current you have at full throttle ? If not then connect a wattmetter and see if you are below the recommanded values.

 

If you are too high, then lower your batterie voltage (switch to 3S if you are at 4S) or use smaller propellers.

 

I'm using AXI motors. Expensive but well manufactured and with good quality roller balls. I don't go over the recommanded max continous current. I tried Pulso as well, but in the end i choosed AXI for roller ball quality. Pulso did have noisy roller balls. Magnets seems stronger on the AXI, detents are cleaner.

 

 

 

 

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Permalink Reply by Greg on September 3, 2011 at 5:26pm

Olivier no I did not check max current at 100% throttle and I should. I used posted data of 20A current draw at full throttle with 12x4.5 EPP props on the 880kv motors I have from jdrones. For this reason I used 30A ESC,s. The battery I am testng with is a Hyperion CX G3 3S/11.1v 2500mAh, discharge 25C. S I obviously need to know the real figures now.

Your the second person to recommend the AXI. Do the mount holes match the Arducopter mount plates? I have found the cheaper A-2836/9 880kv motors quite variable in quality. They dont have good roller bearings, even after a few test runs several are noisy. I have had one fail the instant it started and another from yesterday with a wiring issue. I bought two replacements last week and the magnets seem very weak in one compared with the other.

What model AXI are you using and with what brand/rating ESC combo?

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DeveloperPermalink Reply by Olivier ADLER on September 4, 2011 at 3:11am

 

 

I'm using AXI 2814/22 and 40A opto ESC from Hobbywing. As they are opto, you will need an external BEC to power the electronics. I rely on Castle Creation BEC for this.

 

This is a quite powerfull setup to carry heavy loads. Not sure you need this on the base frame and i think the fixation is not the same width. But you could use smaller motors from AXI.

 

AXI are expensive but they have a more serious design with 3 roller bearings instead of two on Pulso for the same motor size and better quality checking. On the Pulso, i've found that when they are hot, i have some radial play in the shaft. This mean that the roller bearing adjustment is not ok.

 

As i plan to put an expensive camera on the frame, i couldn't tolerate that level of quality and i prefered to spend a bit more for motors.

 

There are higher end motors than AXI, but AXI seems to be a quite good quality / price ratio if you want enhanced reliability.

 

Do not forget that good ESCs and perfect wiring is 70% of the success. I would recommand to test the setup on the ground during a couple hours, with many motor start, stop, slow and fast throttle ramps, to be sure that everything is correct and can support max load before to fly.

 

The only thing you should never do with sensorless ESCs when testing, is to stop motors and start them when the propeller is still rotating slowly. In this case there are great chances you'll have a motor stall, and eventually a motor destruction if you are using low cost ESCs without current protection.

 

This is because backEMF fields are too weak when the rotation speed is slow, causing a false synchronisation between motor and ESC.

 

I think that the best is to program a switch on the radio to be sure that you can't stop motors after start. The same switch can be used if you need to stop motors urgently.

For this i used the throttle cut function set at 0%, and i reduced the EPA (end point adjustment) to 80% for lower end part of Ch3. So when the throttle cut switch is engaged, your motors can't start, but you can Arm or disarm them because throttle is locked at 0%. When the throttle cut switch is disengaged the minimum PWM value is never less than 20%, so you can use the throttle  stick normaly, the motors will never stop, and you will not be able to disarm them accidentally during flight.

 

 

 

 

 

 

 

 

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Permalink Reply by Greg on September 4, 2011 at 5:41am

Olivier great advice. I have a similar Castle BEC so no problem if I switch to the opto ESC.  Are these optos the the funfly or pro series your using?   I was building for a heavy lift quad and yes the basic frame is not the best.  I am doing some mods to mine but for now I will try to aim for the smaller AXI 2217/20 840kv with the 12x4.5 props.  I noticed AXi now have short shaft versions with longer (600-700mm) wiring. Although the Kv rating is lower on these for some reason.  Good suggestion on the throttle function setup.

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DeveloperPermalink Reply by Olivier ADLER on September 4, 2011 at 6:04am

 

I'm using Pentium Opto ESCs. Yes i have this short shaft version with longer cables. You'll need the propeller support kit as well, it is not in the motor box.

 

 

 

 

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Permalink Reply by roger on September 4, 2011 at 3:41pm

Olivier and Greg,

 

Posted something but for some reason its gone. Anyways, what's your target "heavy lift" weight (i.e., all up weight including everything) for the motors you're using.

 

Thanks.

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DeveloperPermalink Reply by Olivier ADLER on September 6, 2011 at 10:48am

 

About 5 kg. Total thrust about 10 Kg.

 

 

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Permalink Reply by Greg on September 6, 2011 at 3:17pm

Well thats encouraging. My aim is to have 4kg to play around with on payload. But from a flight duration perspective weight saving will help increase the fly time to a point.

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AdminPermalink Reply by John C. on September 6, 2011 at 6:40am

Are your motors hard soldered to the ESCs?

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Permalink Reply by Greg on September 6, 2011 at 2:52pm

Yes. I use high quality bullet connectors for initial bench testing to get the motor directions correct and swap parts arround. I then hard solder to the ESC's once I am ready for actual flying. I also watch the wire lengths are consistent and kept to a minimum with enough so that the is no overdue tension and I have some for future maintenance work

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DistributorPermalink Reply by Dany Thivierge on September 7, 2011 at 8:24am

from the look of it when you started your motors the one that failed started later than the other ones... this to me looks like a failing ESC or ESC calibration not done right (but I would really first look into bad ESC. 

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