Coaxial Cinestar...

Discussion in 'Cinestar Misc' started by Benjamin Rowland, Jan 26, 2013.

  1. Alex Smart

    Alex Smart Member

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    Hi there!
    I just got a SjX4 that came with TM4014 330kv and 15x5 props, to my surprise it took over 50% of throttle to get it of the ground,with no payload:eek: I´m running an A2 on default coax mixer and 6s batts, any advice??I´m new to DJI so I may be missing something..also the tr
    hrotle seams to react very slowly it takes about 5 seconds to react the stick imput, is that normal??
    Many thanks
     
  2. Shaun Stanton

    Shaun Stanton Active Member

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    Barring any other malfunction from what you described could be the ESC timing is out of sink. If your ESC's are programmable you might need to play around with the timing. Another possibility is the frequency could be high as well.
     
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  3. Shaun Stanton

    Shaun Stanton Active Member

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    Did you ever get your system working? It sounds like you almost have the same setup that I do in motors. I am using the native settings on the freefly ESC's which are 800mHz for the refresh rate and 15us for the timing advance. I have been getting good results with XOAR beechwood multio-rotor props. I think they work better for these high torque motors at 6S since they provide more inertia to help the motor spin. I dont seem to have any issues with responsiveness either flying in all different configurations. In fact I wonder why I never used them before? I am using 16X.08 at 5300 feet of field elevation. If you are lower you may want a slightly thinner pitch like .07. I get 18 Minutes on a no load flight with 10,000mAh.
     
  4. Jason Herring

    Jason Herring Member

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    What is your normal payload weight? What flight time do you get loaded down?
     
  5. Alex Smart

    Alex Smart Member

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    Hi Shaun,
    I just changed the motors to 4014- 400kv and it´s much beter! I´m getting 12min with 9.3 kg with 15x5 T-M props.
    I didn t touch the ESC, they are T-motors 40A 400Hz.
    To be honest, I think it was my fault, after 4 years of using MK and flying always in atti without AH, much more responcive rig etc. I´ve caught the trick on the skyjib and very happy with it, just need some teeking to be more stable in the wind..
    I will get some Xoars soon, hearing good things about them and they are much cheaper that Tm ones.
    Best Regards
    A
     
  6. Shaun Stanton

    Shaun Stanton Active Member

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    Flying a DJI Ronin and a Black Magic 4K with all the video converters I am at 14.6 pounds. The frame with a 12,000 mAh battery is around 10.5 Pounds. Basically flying 25-26 pounds total. At 12,000 mAh I get a good 6 min 15 Sec of safe flight time with maneuvering with the last 45 seconds to be on the ground before the FF ESC's force the issue. With a 10,000 I am at 5 min flat. 16,000 starts getting dicy the copters ESC's start getting warm. Motors seem handle it well. I get 7 Minutes. As you go higher in battery power the weight goes up and the speed of the motor to power required is not linear. I think with a more robust ESC set with cooling I can get another minute with maybe 18,000 mAH or two 9's in parallel. I find that it is more optimal to have batteries in parallel once you star getting upto the higher weights. The singleton battery really hates the load dispite what the C rating is.

    I am going to try putting a slightly finer pitch prop on top to see if that gives me some more efficient thrust. In theory the thrust lost in coaxial motors is due to the bottom prop moving through the air faster because of the air from the top being pushed on it. I am loosely estimating a 5% gain in thrust. Which does not sound like much, but when talking these numbers 5% can be another couple pounds or another 45 seconds to a minute of extra flight.

    I will post more on this later once I get the props and fly it in decent measurable conditions.
     
  7. Jason Herring

    Jason Herring Member

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    Thanks so much for all the info, I to have an x8 with tmotor 4014, 330kv with wkm, I'm wondering what a safe payload and AUW would be with that setup? I'm using 16inc props
     
  8. Shaun Stanton

    Shaun Stanton Active Member

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    If I were to throw a hip pocket number out I would guess a 10 pound payload at 20 pounds total would be a safe. Probably looking at 10-12 min threshold with 12,000 mAh.
     
  9. Micke Norlander

    Micke Norlander New Member

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    Whats with the negative values? im considering trying this on my Tarot Ironman1000 X8 since i had bad experience with the DJI mixer setup.
     
  10. Shaun Stanton

    Shaun Stanton Active Member

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    The negative numbers represent what side of a particular axis the motor effects. In this case the front motors that contribute to pitch have a negative number and positive for the rear. For roll it's all of the motors on the right are negative vs all on the left are positive. For yaw all clockwise motors are negative and all CCW are positive. The signs tell the flight controller which motors are front, rear, left right and spinning ce or CCW respectively l.
     
  11. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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