Hi Everyone. I've been searching google and this site for videos, studies, tests, etc.. regarding the optimum setup for staying in the air with ArduCopter after a motor failure. TriCopters and Quad's would certainly crash quickly. What about Hex, Y6 Hex, Octo, and X8 Octo. Has anyone seen any testing done to see what the best configuration is? I'm getting ready to build a hex and was originally considering a Y6, but I've been told and have now seen a video that shows they don't always stay flying when one motor goes out. Will a hex survive an in-air motor loss? Does anyone have any links to studies or tests of various configurations?
Thank you.
Replies
Here's what I've discovered...
To stay airborn, your best bet is an octo. After that a hex. There are many youtube and other videos showing Y6 and X8 systems crashing during a motor failure. The reason for this is because in a Y6, the motors are 120 degrees apart. In a X8, the motors are 90 degrees apart. This is the 'normal' scenario. In a Y6, a single motor does not have enough power to compensate for a 120x2=240 degree failure of the failed motor. In a X8, a single motor does not have enough power to compensate for a 90x2=180 degree failure of a failed motor.
Theoretically, If they are strong motors and the code was written to help the motors overcome the failure, it should work, but I don't think the code has grown enough to compensate. For example, in a Y6, the code is designed to turn on 2 motors per shaft. I don't think the code knows that 1 motor is out... so it only half powers that shaft (via one motor), so the nice pretty expensive bird falls rather dramatically from the sky.
In an Hex or Octo, the motors are closer together (in degrees), so the adjacent motors help to compensate for the loss which makes failure more (not perfectly) recoverable.
Hope this helps someone else.
Dave.
I've been researching this myself a bit and can't find a clear answer. Some say yes, some say no, a y6 does not have the ability to remain airborn with 1 motor failure.