Octo X8 Coaxial - testing motor redundancy

Testing the octo without 1 of the top motors and then 1 of them bottom motors to check what's happens if a prop/motor/esc gets bad during flight.

Previously I've done the same test with a flat hexacopter and an Y6 but they didn't performed very well.

With a flat octocopter, if it looses 1 motor/esc/prop it's barely affected. I was flying my octo and it lost a blade of a prop but I just noticed after I landed.

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  • That's the video. Thanks Vince. 


  • BTW, look at mikrokoper forum.

    It have tons of tests with motor failure using octos.

    Its due more than 2 years ago and are death tread for now.

    Coax octos have too much power loss. I think more than 15%.

  • Nice video Vince ;)

  • By the way, I also disagree that a spinning quad is more dangerous. It would probably descend much slower than a falling quad and would make a lot of noise to alert people.I have been hit by big propellers on model aircraft many times and only had small cuts. A 2KG quad on the head would not be nice.

  • If you believe this only worked because he only cut opposite propellers then why could the code not stop the opposite motor if that was the appropriate action. I believe that physics says it is possible but its just needs some very clever code to recognize a failure quickly. 

    I expect in the video they loaded special code for a chopped up quad but it still shows it will fly.

  • As you can see , the quad continue with 2 small propellers.

    Any problem with this configuration. The 2 small prop can stabilize the quad but not stabilize the YAW.

    I want to see a similar video but with only onw propeller cut. This will not work because the big prop continue in the same speed for a little period of time but sufficient to made a flip,

    Try this one, make a quad and change only prop by the big one or another prop with same size but much more mass.

    You can see that the prop with more mass need much more time to speed down. To solve this you need a ESC with special code that decelerate the speed but ever with this esc the quad need much more time to stabilize the axis with propeller that have more mass.

    BTW, i not need a safe strategy to land my quad. I need a SAFE strategy to protect people around the quad.

    Imagine you landing the QUAD turning YAW very fast in the middle of people.

    It can be more dangerous than a quad flipping.

  • I think I've seen that, spin very fast.

  • Somebody has told me that there's a code that allows a emergency descent with the quad if 1 motor gets bad but i don't know if it's true.

    If you could spin it in yaw very fast it would create a gryoscopic effect that would mantain it leveled although you wqould be running just 3 or 2 motors but i don't know if it's pratical

  • On quad its impossible to fly without one motor.

    Only using some kind of variable pitch or reversing motor this redundancy will be possible.

    I tried this type of redundancy 2 year ago without success.

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