Testing X8 configuration without two propellers

Yesterday I had a few tests with our Tiger Shark in Octa Quad configuration.

The tests were made to see how the copter would cope the loss of one or two propellers.



Obviously the test was in a ideal condition where the propeller just loosens and falls off the Octo.

The test was done by removing first 1 propeller, then two propellers spinning in opposite and same direction.


Without 1 propeller the copter flew as it had all the propellers. There was no feeling of something wrong. It took off and landed easily.


Taking off two propellers spinning in the same direction (lower front left and lower back right) resulted in a copter that in take-off yawed a little. Once the I term build up, it was perfectly straight. It was a little unstable due to the fact that two arms were "stronger" than the others, but generally it was perfectly stable even with some wind.




Taking off two propellers spinning in same direction (lower front left and right) resulted in a copter trying to move forward with quite a pace. I took a little pitch back to keep it still, but the overall stability was amazing.....


X8 will not take the loss of two propellers on the same arm, that would result in a crash, unless the recent algorithm gets published and then implemented in ACM code. :)


The code is based on APM:Copter 3.1.2 but runs on VRBRAIN.

Propellers are 13x5 T-motors on the upper and Graupner 13x8 on the lower.

Motors are 3508-700KV with 10Ah 4S battery.

Total weight was about 3.0 Kg.


Thanks to VirtualRobotix.it for the frame and the electronics, and thanks to the APM:Copter dev team that allowed us to fork and use their code, that is progressing fastest than speed light!






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  • Developer

    Bella Emile!

  • This is not the same as others I have seen with a slo blow fuse so the esc stops mid flight, taking off and flying around minus props is completely different to losing a prop mid flight.....cant wait till you try it!

  • Moderator

    Great Job Emile !!! :)

  • hello 4xdrones. No not yet. I will shortly implement a function to switch off 1 or 2 motors in flight. This was just the first test. Just to be sure everything works as expected.

  • I want to simulate this situation for long time! It's impressive! Did you try to simulate the 1-2 props/ motors losing control during the flight? 

  • Wow 780g is amazingly light for a 10A. I was getting 2x 4.5A Nano-techs for about 460g. Its too bad because I need two to spread out the weight. Well at the price it compares to, I think I'll experiment with the Li-Ions.

  • My X8 could get a little more weight loss, but I'm quite happy with it.

    It is very agile compared to radial 8, lighter because it has only 4 arms and you can use the same motor mount for both motors. Then, I am using DualSky 10Ah batteries, very light. they come out at < 800gr. with cables. When using 2 5Ah Zippy compact I go over 1 Kg.

    So that is a start.

    Everything else is just the good of carbon fiber :)

  • Yeah the APCs create too much prop wash, maybe it would be good for the top. But I would bet that your 13x8 is acting kinda like a turbo prop. Basically super charging the speed of the thrust instead of moving it at the same speed.

    I was going to say an X8 3.0kg AUW was not possible =). My ultralight Hexa 800mm is about 3.0 AUW with 9A 4S.

  • Hello, honestly I have not tested current consumption with same prop on bottom.

    I did try using APC 12" on the bottom with not so good results. So once I switched to graupner and saw that everything was working fine and had less than 50% with a 4.1 Kg AUW I left it as it was. :)

    The setup in the video is without gimbal and camera (of course!) and is 3.0Kg (more or less) with the 10Ah battery.

  • That's great to know the redundancy is working! Awesome. That's probably the best advantage for an X8 config.

    So how is having the Graupner with high pitch on the bottom? I find that really interesting since you're moving more air on the second stage. That might actually be more efficient compared to the same prop.

    Is it 3kg no batteries?

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