Hexacopter flips with no apparent reason

Hi all,

I know that this is a very recurrent question and I apologise for any redundancy.

I assembled recently a Tarot T960 frame, T-Motor MT3514 400 (X6), T-Motor ESC 40a (X6), emax 6 axis power board, Pixhawk, 3DR GPS module(X2), 3DR telemetry radio, RC Taranis X9E and receiver X6R.

I managed to get it airborne during first trial, but unfortunately, one of my props was not tight enough and came off in the middle of a flight. The hexa landed with the arm missing the prop, which obviously broke. It also inutilise one of the land gear arms.

After getting the spares and assembly the hexa again, it doesn't want to fly. Instead, it flips as the video shows.

Any ideas on what could be wrong?

Yes, props are all spinning correctly, motors seem to have the same speed, no weird noises, frame set to X shape, etc.

https://drive.google.com/file/d/0B_iZNL5M2cKIU2dxN0FqMHNZZ28/view?usp=sharing

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Replies

  • Developer

    Hi Arnoldo,


    This is definitely caused by incorrect motor connection, frame type or orientation. I would suggest reloading the hexa code to make sure you have the right frame. Setting the frame to x type to make sure you have the right orientation. Then I would ensure the motors are connected so that during the motor test you get clockwise rotation from 1 o'clock. After that just double check the prop directions (I know you already did this).

    I am sure this has already been said in the thread but I didn't read all your replies.

    Good luck!!

  • If you disconnected any motor wires, you could have cross wired the motor. Just swap two wires and you should be good.

    Check the direction of spin on each motor and the prop for CW or CCW. Make sure each motor is the motor it is supposed to be.

  • Just give it to me ill make it work and sell it back to you !! Sounds like a deal ????? lol 

    Check that the motors are all sitting very FLAT with respect to one another. I use a phone app for that. Like a level of sort. 

    • I don't really mind outsourcing these type of things, I don't really have time for them. All I want to do is to fly a camera that I'm prototyping.

      I'm in Cambridge, UK, so if you are close let me know.

      • I would arm it and with someone elses help hold it by the legs and keep it above ur head and add thrust. see if it just wants to go one way something is in reverse.. 

        • This is horrifically bad advice!  Don't do it!!!

          The first check should always be the motor tests that are built into MP and APM Planner.  Take all your props off and start each motor in turn and check a) the correct motor starts that you're expecting, and b) it rotates in the direction you're expecting.  Very simple, very effective.  I learnt the hard way to do this after flipping a couple of new builds!

          • Hi Fnoop

            I did the motor test this morning, and I had all my motors spinning in the correct order. I think my problem right now is that props might not be completely flat. The motor mount of one of my arms is slightly bent up, due to one of my crashes. Moreover, there might be some vibrations, and unbalanced props. I didn't expect it to oscillate so wild to be honest, but I was expecting some sort of imbalance I was hoping to be able to reduce after flying a while.

            The other problem I have is that is a massive frame. Anything you do with it is extremely dangerous, not so much for others but for itself. The tiniest crash ends almost certainly in a broken leg or arm. It's heavy, powerful and very difficult to pilot, if you don't have it properly tuned.

            Having said that, I will try to level all the motor mounts, reduce vibration in motors and balance the props. I just wonder if that's really the problem for such wild oscillation.

            • Wow, this sounds like quite a first project!  What's the frame?  A picture might help.

              Bent arms/props certainly won't help but I'd be surprised if that was causing wild oscillations.

              • Yes, motors twisted or/and  umbalance props can make a horrible performance.

              • Hi Fnoop,

                It's a Tarot T960 (almost a meter in diameter), Motors are 400 kv, and props are 16"X5.4.

                I also think that this might not be the sole cause of all this performance. What else comes up to your mind?

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