Hi everyone, thanks in advance for reading my note here. I did do my best to read all the docs but could not find exactly what I was looking for - am hoping you much more experienced drone fliers could help a noob here...

I bought my excellent hexacopter from USR just over a week ago and have gotten the various additional parts (radio, batteries) together to fly it.  Today I finished my ESC calibration and, being a coder, habitually updated to the most recent firmware (eg 2.8.1 to 2.9.1...).  Hm.  I then realized this involves some uh, recalibration, and did my best on that.  Carefully calibrated the accelerometer as in the ArduCopter 2.9.1 instructions on this forum.  And redid it a couple times to be sure... but I don't think that's it.  Have not yet added vibration dampening, since I just got the USR drone and need to get more parts to make room for foam (could the lack of foam be leading to my symptoms below..?)  I checked my PID values in the ArduCopter Config - they were as shown in the 2.9.1 instructions.

So when I carefully throttle up - as soon as the hexacopter lifts off it goes into a mad spin - either to the left or to the right.  The yaw control does seem to have some effect - I can make it spin right or left.  And it seems like it wants to start spinning faster and faster before I throttle down.

I was thinking to try to tweak the stabilize yaw value - but not sure what value to try and also, seems like the problem could be larger than this..?

Or am I missing something on resetting the gyros before flight ..? or ..?

I'd greatly appreciate any thoughts you might have on this... thanks again for your help and I hope to someday repay the favor.


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I tried recalibrating the ESC's - same behavior.  Strange thing is the compass points accurately when I am on USB or on telemetry - I can move the device all over, no problem, compass is accurate, as are other accelerometer axes.  And zeros out accurately.

Radio sticks are all calibrated and centering accurately.

Hope someone can help. Totally stuck over here.  Thanks.

Hmmm... which end is the front? The top of the image, i assume. If that's the case, and it's a little hard to tell, it looks like all of your cw and ccw props need to be swapped. Then you may need to flip all motor directions as well. Stare at this page for a while and you will be ok: http://code.google.com/p/arducopter/wiki/APM2_Motor_order

Of course, if the bottom is the front, as designated by the two blue arms, your props are good... If none of this helps, hopefully someone else will glean something useful.  :)

Ah... that was in the manual right...?  Ok... just "erase" from the CLI?  Then of course all the configuration steps again?  Will do.  Thanks!

John, I double checked this in detail and compared it to the motor pics in the manual taken from the link you provided.  I am pretty certain I have the right rotation and propeller order.  It does fly... just spins like mad after liftoff.  

The two blue arms are the front...

Thanks much for your thoughts!

does anyone know if it is better to just issue the 

> erase

command or the 

> reset 

command - or erase then reset?

Here's a video of what this looks like if you try to lift off (and yes - calibrated the radio.  Throttle works great, I haven't reversed my yaw...).  My next steps are an "erase" command and a recalibration of magentometer and accelerometer...

Anyone else have any ideas on what is going on here?


After seeing the video I am suspicious that you have a single motor or ESC that is behaving badly.  The lack of lift on one side combined with the spinning motion is an indication that a single rotor is turning too slowly.  Try this:  For each motor on the side of the hex that is not lifting pull the 3 wire plug from the ESC that goes to the PDB and plug it into a separate radio receiver.  Power that motor individually at 40% throttle.  Do this with 3 motors on that side of the hex.  See if one is behaving different than the other two.

Thanks!  Will try that when I get home tonight.  All the ESC's were calibrated - 3x actually... will work on it!

It is also possible that the motor and ESC are fine but you have a bad electrical connection.  I found those barrel connectors to the motors to be absolutely awful.  They resulted in motors losing current during flight and eventually a random crash.  My solution was to solder all the motors to the ESCs.  In your hex that will be 18 solder joints.  If a motor is spinning too slow (I think it is) you can also check the barrel connectors on that motor and the PDB solder joints, connectors, etc.  Make sure you do not have a cold solder joint anywhere.

Try this test too:  Tie your hex down tight on a level surface.  Run motors faster than hover speed (maybe 40% or 50%).  Look at each motor very carefully and see if one is running slowly or at an inconsistent speed.  Wiggle wires, connectors, etc.  Be careful not to let a prop hit you.

Your hex is so wonky in the air that I bet you will identify a motor running too slowly just by looking at it.

Thanks for the help everyone.  I send the drone back to 3DRobotics for a fix which appears to be ESC or soldering related.  They agreed that that seems to be the issue.

I appreciate the help and hope to return it someday!


Hi Quinn,

Thank you for your business, 

A new replacement unit configured with your Turnigy RC and battery, test-flown, will ship out by Monday or Tuesday of next week, expect the tracking number by email. 

I'll personally check your RMA (love to troubleshoot these) tomorrow morning, will take pictures and post update here. 

Best regards,


Hi Quinn,

We checked your Hexa, RMA#86. We first had an error while trying to upload the code, it failed on the first two attempts, but on the third one was successfully uploaded. Then everything went as normal, ESC calibration and RC configuring. Put the props on and we had a successful & smooth flight http://youtu.be/4_KKnfBAEto. We will look further into the APM. Your new unit will ship out tomorrow, along with your RC and Lipo.

Thank you, G

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