Investigating a potential flip of death - S800 & A2

CloudVisual

Member
I hoped this day wouldn't come, but the S800 crashed yesterday, luckily whilst out training in a grassy field.

I didn't have an iosd logger, so this is all the information I can give:

Wind was a steady 8mph and it was sunny.

Had two flights previous to this and all was fine. Did some RTH tests and IOC flying.

I'd bought a new Lipo for testing, a Turnigy nanotech 8000mah 6S and wanted to do a hover test to see what the flight times were like with a fully loaded S800 with camera and gimbal. (with evo arm upgrade)

It was taken to hover and sat there nicely for about five minutes. I noticed a tiny twitch as if the gains were slightly too high. The day before I had the same twitch and took the gains down by five just in case, so this was strange to see after what I did the day before.

About twenty seconds later a more noticeable twitch occurred, but nothing to raise concern.

The twitch reoccurred twenty seconds later and it was twice as big as the last (exponential overcorrections)

So by this point the twitch is enough for me to think it's worth moving the S800 to eliminate this and hopefully tell it that I'm in control and give it a new stick command. That's when a full 45 degree tilt and recover occurred.

On recovery I attempted to land it, but I flew it away from me in case something went horribly wrong. I got it 30m away and was about 6ft off the ground, ready for a landing. This is when it flipped 90 degrees and smashed into the ground, breaking four of six props, one fractured arm and pinging the camera equipment across the grass.

I picked up the pieces and got home, fully rebuilt it and took the props off. Ran all the system to check for failures and to see if the left nose motor had failed. It was all fine.

I've been sat here thinking the motor must have cut out, but it then dawned on me that the only prop which broke on both sides was the one which I thought may have cut out, which can only mean it was spinning at speed to break like that.

So, I'm feeling quite lost at the moment. I had replaced my A2 FC about three months ago, after having LED code issues.

Sadly none of this was filmed. Any thoughts?!
 
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kloner

Aerial DP
what you explain seeing is exactly what they do when a motor is leaving, kept getting hotter and worse..... You can predict this by watching props off motor checks, rev it up and down in manual and feel booms for any vibrations. if you feel ANY change the motor making them....
 

Benjamin Kenobi

Easy? You call that easy?
Yeah, sounds like a motor/ESC failure. I've had that twitch before and then the ESC failed shortly afterwards. A 90° flip is quite a bit though! Mine wobbled 45° but once the motor stopped it was fine and I brought it home with 5 still running.

Replace the suspect arm.
 

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