y-6B won't lift off of ground on initial flight test.

just completed assembly of 3d robotics 6Y-B and can,t get it off the ground.  The battery voltage goes from 11.8 volts to a low of 10.6volts as the throttle is raised from zero to 100%.  You can lift the right side or the left side but you cant get the rear arm to lift.  MOTOR ROTATION AND PROP INSTALLATION CHECK OUT OK.  I need advice on where to look next,  Any suggestions would be appreciated'  thanks Tom 

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  • if your using a 3s battery fully charged should be 12.6v...if its already dropping to 10.0v on throttle up it's close to voltage cutoff...i don't think a 3s has enough volts to give these 850kv motors enought trust to lift ...try a 4s 5000mAh -10000mAh..hope it helps.

  • In my own Y6b build myself as we speak. I had 1 arm lifting two not. My earlier stage tests I swore checked out (I swore it! ) only to discover 1 motor (rear top) had wrong spin. Fixed that. Then my next test got full throttle but no lift. More swearing (actually swearing I did it right) only to realize I had push pull swapped top and bottom. Thrust just ensured I was locked to the ground. Not saying that is your situation but a little similarity as I wondered esc and tx calibration and was solving wrong problem for myself. I now have great lift but with a major counter clockwise spin - but I am 1 step closer! I think!

    • Sorry that I am so late getting back with more information on my problem.  I have re-checked my motor rotation and also made sure I had the correct props all facing with the lettering towards the sky. I also checked that the esc leads to the power board went to the correct location so that esc control lead from esc #1 went to the proper #1 position and #2 went to the #2 position etc., etc..  I also checked and verified that the correct color ( in my case blue for the first esc ) on the 6 wire wiring harness from the power distribution board was also the first color on the PIXHAWK.  I also am now using a 4 cell 5000 mah battery.  The result was the same.  When tested the rear leg motors 3 and 4 still wont spin enough to tip the 6y-B forward.  The 6y-B will tip right or left with the correct command from the radio but again the rear motors don't have enough power even at full throttle to lift the rear leg. At this point I need to identify if I have a bad speed control or a bad motor at position 3 or 4.

      My question now is what is the easiest way to determine if I have a bad esc or motor.  I can switch esc's around and see if that results in my power problem moving to another arm or if it stays the same arm I would know that I have a motor problem and the esc's are ok. What it won't do is show that I have a pixhawk problem. Question is there a better way to determine which componet is bad?  Suggestions please.

    • Problem solved.  I replaced the number 4 esc.  The 6Y-B flies fine now.

  • @Thomas,


    Have you reviewed the instruction manual at copter.ardupilot.com?

    1.  Recommend you verify that you have all ESC pinned out to APM/PIXHAWK correctly.

    2.  Verify all propellers are mounted and rotating correctly.

    3.  Perform ESC calibration with your Transmitter.

    4.  Suggest you try a 4S battery as the 3S may not have enough volts to lift your Y6 for very long.  I use 4S 6000 mAh battiers.  If you do step up to 4S you will need to recalibrate the ESCs.


    Again I suggest going to copter.ardupilot.com website and review Instructions menu.

  • Does sound as though your battery is potentially suspect, did you check the voltage on your charger or through the logs and have you calibrated the voltage in your pixhawk / apm, it could be giving you a false reading.

    If all of the above are correct I would suggest you may have simply put your bottom props on upside down. Basically you should be able to read the writing on all props (APC 10x4.7 SFP top and APC 10x4.7 SF bottom) when looking down on the Y6 from above. If you have the bottom set on upside down you won't be able to lift off the ground without full throttle and even then only for a few seconds, and the motors will be running really fast. How do I know this, it's exactly what I did when I first completed the build, after flipping the bottom props over you realise how slowly the props can be spinning to get you airborne.

    Hope this helps.

  • If you are using a 3 cell battery your voltage should be starting off from ~12.6 volts, and will sag to ~11.6 on intial load ... a starting voltage of 11.8 volts sounds like your battery is not fully charged (more like less than half full) so that could be part of the problem, but it all depends on what motors etc you are using the weight of the aircraft with any added extra payload etc.

    List out the specifications of your aircraft and the battery you are using, and if you have a log of your attemt to take off add that to this post too.



  • Try (carefully) holding the y6 above your head (maybe wear gloves and a long sleeve coat if you're clumsy like me) and test. Could be you need to calibrate escs, accelerometer, or compass).you might need to be less tentative on your throttle during take off. Am on my phone now so sorry for the short answer... Good luck!
    • If you put the stick fully forward and it doesn't go forward, perhaps the pitch needs to be reversed on the radio controller.
    • Give us the specs on that battery, too.  I don't know any good reason it should drop the voltage that much unless your battery is weak or damaged.  

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