NEW U7 motor tmotor

Discussion in 'Cinestar 8' started by kjetil tønnesen, Nov 22, 2013.

  1. Bryan Harvey

    Bryan Harvey Member

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    Howard, I have indeed read that in forums, however I took my cues from everyone I asked who are running these motors, and anyone who has ever posted on any forum regarding using the U7 motors (including all the people on this very thread). They ALL are using ESC's in the 70a to 80a range. However, most of them have the 420kv motors. I'm not sure why there would be that much of a difference between the 420kv and the 490kv and ESC choice, but we are thinking that this may be why we got the unfavorable test results.
     
  2. Howard Dapp

    Howard Dapp Active Member

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    Got it. It could very well be the Hobby Wing controllers and possibly the PWM frequency they are running.
     
  3. Bryan Harvey

    Bryan Harvey Member

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    KDE4014XF-380_Performance_Data4.jpg

    the specs on these new motors from KDE are amazing. very high quality and 100 grams less than the U7's. thats almost 2 pounds on an X8.

     
  4. Dave King

    Dave King Well-Known Member

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    Do you guys know if they gave you recommended running specs for timing and pulse width etc?
     
  5. Kari Ylitalo

    Kari Ylitalo Member

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    I did maiden with my new build X8 with U7s today and had a similar thing happened after 1 minute in air. Difference is my machine was with wookong and simonk flashed esc:s which worked well in bench testing. AUW was slightly over 10kg with 2X 5S 10ah batteries. There seems to be something weird going on with these motors and 15" props. It was keeping quite loud whining sound when yawing and i noticed yawing didn't feel symmetrical at all, after couple of stronger yaws copter just drifted and dropped to ground and flipped over. Fortunately i was only 2 meters above the ground and only couple of motors and props had scratches, i need to open the motors tomorrow for complete check for damage. I have square tubes so motor alignment is not the problem, but still it really does not feel all is right with symmetry. I did read this thread before and didn't believe it could be issue with motor/prop combo, but now i'm beginning to change my mind. Looks like it's not necessarily MK issue at all! Be careful out there with U7 and 15inch props guys! ;)

    Dave what frame did you use by the way? Just wondering if you have checked if the arms resonates with some frequency close to motor rpm to affecting jitter to airframe and so on over saturation of IMU data. I will do some testing tomorrow regarding to that.
     
  6. Dejan Mugosa

    Dejan Mugosa Member

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    Just a note. Overspin on motors with 15 inch props.
    Second. High poles motors dont work well with MK board (not fact but still in testing phase) and simonk esc dont work at all with high pole motors. As soon as you move trottle too fast they shut down random.
    Sugestion : HERKULES III board.
     
  7. Howard Dapp

    Howard Dapp Active Member

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    Just an fyi, here are the recommended ESC settings for U7 motors from Tmotor:

    The timing: default 15°
    ESC PWM: 8-12kHz
     
  8. Chakradhar Raju

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    24°, 18°, 12° Programmable Commutation timing
    PWM frequency : 8kHz to 16kHz PWM switching frequency programmable

    Would this be OK...
     
  9. Kari Ylitalo

    Kari Ylitalo Member

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    U7 is 12N14P so not really high count pole motors. MT3515 is 12N14P as well which i've been using ages successfully with SimonK flashed escs. Agree with overspin possibility affecting dropping from phase but on bench they are working ok. I like to hear more details of others setups so we can try to find what else is similar in our setups.

    Even though 1400€ HERKULES 3 is sweet it's not necessarily saving us from this problem..
     
  10. Dave King

    Dave King Well-Known Member

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    After my copter freefell with the U7's Flori thought that 15 inch props were too small and that the motors were overspinning. If that's true its a bit misleading on Tiger's specs because they publish the specs with 15 inch props. If they don't work right with 15 inch props I would think they wouldn't publiish numbers for them because when they test them on a specific prop they really run the crap out of them. They seem to be very specific on which props they spec with each motor because not all motors are spec'd with 16 inch props and many 6S motors aren't spec'd with 14 inch props.

    During my testing with the U7 motors with the new MK 3.0 BL electronics I noticed two things. The first is that as soon as I started the motors the MK wanted to yaw but corrected itself after 5 degrees and that the motor RPM at idle with throttle all the way at 0 was much higher than anything I ever used before. I also noticed that there was a significant difference between odd/even motor temps and currents and when the motors were absolutely 100% level. I don't know if there's something in the active braking thats throwing the U7's off because I never had a chance to turn active breaking off to test and see if it made a difference.

    If I had a test copter I would love to try the U7's with 16" props, active braking off, and run the timing as low as possible.
     
  11. Kari Ylitalo

    Kari Ylitalo Member

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    Dave,

    are you running them coaxially and which airframe?

    Kari
     
  12. Dave King

    Dave King Well-Known Member

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    I am not running the U7's anymore until I know for sure that they are tested and work. I ran with in a flat 8 config using a CS8 frame that I modified a bit using all alumnium clamps and outboard battery plates. Currently I am running U5's and I'm hovering around 62% at hover at just under 12KG GAW.
     
  13. Howard Dapp

    Howard Dapp Active Member

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    Dave, have you ever tried 17" props on your setup?
     
  14. Howard Dapp

    Howard Dapp Active Member

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    I figured out the issue with my U7s and why the 2 freefly controllers burned up. Turns out it wasn't an issue at all, it was a ridiculously stupid mistake on my part. I allowed the battery to drain down to 21.5v, the copter lost control then slowly came down and flipping over. Once upside down, i neglected to quickly shut down the motors, 2 controllers caught fire because the motors/props were restricted from spinning while still receiving throttle. Stupid mistake on my part.

    My setup with the U7s was a bit heavy, i'll be dropping down to the u5s with an AUW of 26.5-27lbs/12kg.
     
  15. Dave King

    Dave King Well-Known Member

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    I coulld have tried them when my booms were still 550mm but I had to cut them down to 520mm in order for my copter fit in my car in one piece.
     
  16. Lance Robb

    Lance Robb New Member

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    I have just test flown with 8 x U7 motors and have a screeching noise at 40% throttle setting whilst hovering. It's not a mechanical noise and is definitely not right. all 8 motors make the same noise when I run them individually so I'm not sure if I should try adjusting the PMW and Timing or just take them off and send them back.....

    Any thoughts??

    Thanks
     
    Howard Dapp likes this.
  17. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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  18. Howard Dapp

    Howard Dapp Active Member

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    I had the same VERY loud screeching noise. Email Becky Yang at Tiger Motor: sale7rctiger@gmail.com

    Tell her your concerns
     
  19. Lance Robb

    Lance Robb New Member

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    Thanks Howard......What was the outcome when you emailed them??
     
  20. Howard Dapp

    Howard Dapp Active Member

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    Becky and Tmotor are very helpful in troubleshooting any problems. Basically in the end I was told that they have not received any complaints in regards to the U7 motor and maybe the sound is a bad bearing due to a crash. I had to laugh because the motors are brand new right out of the box and my FF controllers are setup according to tmotor's timing and frequency specifications.
     

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