I just got my quad ready for initial flight testing today - everything works good at first, it's pretty solid, even with less than perfect weather conditions. However, after a few minutes of flying, it will flip over and crash upside down. (I didn't have it more than 3-6 feet up, so any flip would result in upside down crash.)

I am wondering if anyone has any suggestions?

Mode was "stabilize."

One thought - I noticed one of my ESCs is getting pretty hot even when the quad is not flying, just from the BEC functions I guess. (I have 4 linear ESCs tied together.) I am wondering if perhaps that ESC overheats and shuts down, causing a loss of power to one motor - and the quad to flip. The one thing about it is - after it's upside down in the dirt and I have reduced the throttle to zero, the motors are still trying to spin for a bit. If the BEC failed - could it cause a partial reset (while another BEC took over, or that one reset) resulting in this crash, and a few seconds to require the signal and detect zero throttle?

Next, I was wondering if it might be my radio tweaking out. I have a 2.4ghz FASST system, and a 900mhz 3DR telemetry radio. Think they may conflict? One thing, if I arm my ESCs, hold down the quad, and turn off the radio, the quad will "freak out." I would think a FASST system should not do that. Reminds me of the old 27mhz stuff.

Any other ideas/suggestions?

You need to be a member of diydrones to add comments!

Join diydrones

Email me when people reply –


  • I've actually had something similar on APM2. I was flying the other day in stabilize (after attempting a mission in auto mode) and the copter flipped over and landed upside down with the motors still running (I had to unplug the battery to get them to stop). I fixed some of the damage (mostly plastic pieces and a prop) and checked out the copter real quick and then decided to try flying again and after hovering for a couple minutes, I attempted to switch to auto and the quad took off the wrong way. I then switched my transmitter to stabilize but couldn't control anything (the sticks didn't do anything). I tried to switch back to RTL and Auto and that didn't do anything either.

    I fly with a separate BEC rated for 15A. 

    I have attached the 1 log file that contained data. None of the other flights appeared to have saved (possible culprit?). Initially couldn't connect on the terminal screen on the mission planner. I unplugged the sonar and xbee and was able to connect. I connected each separately and then together and haven't been able to reproduce that issue. The Terminal screen showed a bunch of ??? instead of the normal bootup. I guess right now I suspect that either the Xbee or dataflash card may be related to this problem.

    2012-08-19 08-12 3.log

  • Update: I disconnected all the +5v wires and used another ESC I had laying around as a BEC... problem appears to be solved. Flew for several mins in loiter mode with no crash. :)

  • I suggest you simplify the installation and use just what is needed to fly, remove telemetry power/connections.

    Battery --> PDB --> ESC (all of them) ---> APM2.x + Radio Rx.

    I use the 3DR PDB and all 4 ESC are paralled out of it for the APM power (pretty sure - ohmed it out).

    Glad you caught the failsafe mode. The documentation says in failsafe, if farther than X(?) meters from launch point, it should rise 30meters, RTL, and then land. I have Spektrum gear and there is also a TX loss failsafe mode for the receiver. Check your Futaba for something similar.

    I have been using a tether system on my quad. If one leg is tethered, I can go about 10ft up. Two legs, 5ft. I just have to be aware of the cord and propwash during liftoff. It wouldn't do to suck that line up into the prop. :-O

  • (I have 4 linear ESCs tied together.) 

    This is not recommended.

    There have been many discussions regarding powering the APM from a single ESC/BEC.

  • Turns out the quad "freakout" when the radio gets turned off was caused by a failsafe being set to 20%... when it looses the signal, it will increase throttle to 20%. That is resolved. However, still wondering what the causes this problem in the first place. I am thinking an overloaded BEC causes one ESC to shut down for a second... causing the quad to flip as well as a momentary loss of power to the receiver, then after the crash it throttles to 20% due the failsafe until the receiver re-associates.

    However, I have 4 ESCs.... if one browns out, wouldn't hte others take up the slack?

This reply was deleted.


Chris Anderson liked Zara Mae Pickering's profile
May 21
Azjeg liked Azjeg's profile
Apr 27
Benewake LiDAR liked Benewake LiDAR's profile
Apr 12
Gremsy liked Gremsy's profile
Mar 12