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NEW U7 motor tmotor

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

  1. John Gore

    John Gore Member

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    For our purposes and goal weight the 420kv version makes more sense (specs below for reference).
    Will use 17x6 xoar props and not t-prop carbon (my own personal preference).


    u7-420kv.jpg
     
  2. Chris Fox

    Chris Fox Active Member

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    Squeezed in the first test flight with the U7 motors and 17 props, I need to do some more flights to get a better handle on the endurance performance, but it was a good feeling get the new bird airborne with a decent payload.
     
  3. Dave King

    Dave King Well-Known Member

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    Chris what electronics were you using with the test and did you have to do any adjustments with them to get them to work? Are you running 17 props with a flat 8 or a co ax? If you are running a flat 8 what size booms did you use?
     
  4. Howard Dapp

    Howard Dapp Active Member

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    Chris, what was your payload weight? AUW of the setup?

    **I see you already answered my questions in the other thread. Looks like you're running Dji with FF ESCs correct?

    **ok, upon further investigating I see that you're actually flying the Super X flight controller.
     
  5. Chris Fox

    Chris Fox Active Member

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    G'Day Howard and Dave,

    Running T-Motor 80A ESCs and XAircraft Super X flight controller ... so far I am happy with the flight controller performance, and the ESCs were cool to touch after the flight, so happy with them as well.

    X8 configuration with 500mm booms, I may trim them down shorter, but not sure yet.
     
  6. John Gore

    John Gore Member

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    Also got in some more tests flights over the last 2 days. Loving the U7 motors so far. Motors are ambient / room temperature on landing after 3 min test flights, with AUW of 15kg. Rock solid in the wind, tested 15kmph gusty so far.

    Motors are 92cm motor to motor on my setup (I prefer a compact bird for easier transport, and see no difference in performance from longer-shorter booms). Looking forward to getting the new gimbal, retracts, and of course RED up in the air, no more sluggish performance on this baby!
     
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  7. John Gore

    John Gore Member

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    The U7 actually has a very interesting cooling system. Without props on, if you run the motors it actually blows air like a fan. Makes quite a different sound too, unlike other brushless motors. Deeper tone, but with bit of the air blowing sounds (fan like).

    For once the product seems to really live up the hype / marketing.
     
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  8. Howard Dapp

    Howard Dapp Active Member

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    Great feedback John. What electronics are you running? Flight board/ESCs. Where was your throttle stick position in hover at that weight?
     
  9. John Gore

    John Gore Member

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    Throttle is just below 50% with 15kg AUW , and at altitude of 1350m (4400 feet). Using DJI Wookong with IMUv2 , 70A hobby wing with power hungry systems distribution board (400A). Changing to Herkules III soon for the telemetry, weight saving and advanced features (but the 70A hobbywing have been bullet proof for us for our RED rigs, no complains).
     
  10. Howard Dapp

    Howard Dapp Active Member

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    Under 50% throttle at that weight with 17" U7/420. Those motors appear to be performing better than the chart!
     
  11. John Gore

    John Gore Member

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    Yes, but the t-motor chart does not show xoar props ;)

    e-Calc (for once) seems to be pretty close to the results I'm getting so far.

    Neither show x8 config, as there are many variables to a good x8 build. Flat 8 is much easier, longer flight times, etc. (but of course x8 is more stable and easier to transport, work with, etc).

    Flight time will be about 7min. (More than enough for our needs, priority is on stability in all conditions, wing, heat, altitude, flight time is not a priority. But you could get more flight time with 18inch and more battery of course).
     
  12. Howard Dapp

    Howard Dapp Active Member

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    Good feedback, thanks. Just collecting all the new U7 info that's streaming in these days before I make the jump!
     
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  13. John Gore

    John Gore Member

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    We actually using Kopterworx kw12 (U7 with some customisations). Its wise to let other try first, and follow suite, but glad we took the chance and jumped in early.
     
  14. John Gore

    John Gore Member

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    kw12 axi 1.jpg


    kw12 axi 2.jpg


    kw12 axi 3.jpg

    A side by side comparison of some popular big lifter motors: kw10 vs axi 4120/20 vs kw12 (U7).

    Axi are pretty amazing for their age. Lots of power, but you need big ESC as these pull amps.

    kw10 are great, but have to work hard to lift a RED in x8 config (flat 8 makes more sense), but we happily use kw10 for over 400 flights on over 25 paid days of work on many test flights, and they performed well. Tend to overheat as they are working hard, so you need extra cooling (lucky we found this out in our initial tests, other were not so lucky and have ruined motors from overloading).

    kw12 / U7 have more power than axi, about 50% more power than kw10. Run very cool. This really is a new generation of motor tech, and a step up on previous motor designs.

    PS: The U7 is for power, U8 is for efficiency, so if you need long flight times U8 may be better, but for RED lifting my current thinking is that kw12 / U7 is the sweet spot for our needs.
     
  15. Howard Dapp

    Howard Dapp Active Member

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    Great info! I'm in the states, would you suggest I order the standard U7 from a local dealer or are the KW12 upgrades worth paying a little extra for by ordering overseas?

    Shame that Axi STILL hasn't jump onboard the multirotor craze.

    You've actually just made it even more difficult for me to decide which motor. Initially I was leaning toward the U7/490 with a 15"-16" prop for lifting approx 13kg. I'm also a long time coax flyer so i'm wondering if the U7/490 running 15" or 16" props would produce slightly longer flight time. Decisions decisions...

     
  16. Ozkan Erden

    Ozkan Erden Distributor

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  17. Howard Dapp

    Howard Dapp Active Member

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    @John, one other question, you are running the same size prop top/bottom on your coax? Are you running the lower at a higher RPM or are both top/bottom spinning at the same speed? Thanks,
     
  18. Steve Maller

    Steve Maller UAV Grief Counselor

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    Howard, FYI, on my X8, I’m running the exact same props, with just a slightly higher speed on the lower ones (MK mixer 64 top/67 bottom). Current draws on the maiden flight were spot on.
     
  19. Howard Dapp

    Howard Dapp Active Member

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    Thanks Steve. It seems that only the MK guys, me included, set the lower motors to spin faster. All others (non MK) seem to be running both bottom and top to spin at the same speed. You're running 67 on bottom, why not 71? Has it been suggested that 67 is a better number. Are you saying current draw for top and bottom were somewhat equal?
     
  20. Steve Maller

    Steve Maller UAV Grief Counselor

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    Before I switched to the heavy lift setup, I experimented with different mixer settings, and found that 64/67 worked. I will do the same with the new motors (Avroto 3515)/props (15” CF), as it could be different. And here’s the MK GPX numbers for my first flight with this rig last night.
    Motor1: 0.0 7.9 13.7 A Temp: 14 30 35 °C
    Motor2: 0.0 8.0 12.8 A Temp: 14 33 40 °C
    Motor3: 0.0 7.3 12.4 A Temp: 14 29 35 °C
    Motor4: 0.0 7.2 12.1 A Temp: 15 33 39 °C
    Motor5: 0.0 7.5 12.6 A Temp: 16 31 38 °C
    Motor6: 0.0 7.1 12.1 A Temp: 13 32 39 °C
    Motor7: 0.0 6.3 10.2 A Temp: 15 32 38 °C
    Motor8: 0.0 7.9 14.2 A Temp: 14 32 38 °C
     
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