Hey folks!

Yesterday I had my biggest, worst and most scary crash with my 3DR Quad.

Our local firefighters had an open day for public and presented their equipment, did some presentations, they had a jumping castle for the kids, BBQ and beer for the bigger ones.

A friend of mine who is always acting as a spotter for me when doing video flights planned to do some aerial footage of the place and in a second flight film the firefighter team during a car rescue.

So I picked up my quad with full loaded batteries, pre checked everything in my office and went to the starting locations. Here I powered the quad up und waited to get a GPS lock. I didn't need the GPS, but I just wanted to make it absolutely right, because I would be flying over a crowded place.

So after 2 minutes of patience I had a stable GPS lock, made sure I had the right flying mode dialed in, in this case I used stabilize with simple mode, so I could concentrate on the flying location while my spotter would give me advises how to align the camera.

A quick spin up test, everything was fine, so I took of, stabilised the copter in mid air 2 meters from the ground for a couple of seconds and pulled the throttle up to get some height.

First position was reached (no mission, no fpv, just plain odd manual control) so I headed to the second position and yawed the copter 90 degrees to the left. After the yaw I felt the copter beginning to drift a little so I pushed him backwards towards me and reverted yaw so the copter looked away from me.

I wanted to fly back to me whitch meant backwards for the copter but the quad started to lean more and more forward. I had fully deflected the stick backwards, but the copter would not come back, ist slowly increased pitch for some reason.

Because of the kids and the people under the copter the only way to recover safely from this situation was to apply throttle and let the copter drift away over the firehouse, keeping it in the line of sight until I could be sure it was over the building towards free space and then shut the motors down.

The result: most important: nobody injured, for gods sake!!!

2 Motors broken

2 arms damaged

GPS unit destroyed

IMU shield defective

maybe more to come, I didn't disassemble and tested everything right now

I have absolutely no clue what happened! So any help in order to understand what went totaly wrong would help!



P.S.: Board Version 1.4, Quad with 850 motors, all settings to stock, Firmware version 2.7.1

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You still seem shaken! breathe in breath out .It is unfortunate you had to kill the copter  you did the right thing under the situation I am not really a Quad guy  but there should be something like a retractable dog's leash and weight  say 20 feet long that could be clipped to the bottom of the copters on fire up  when every thing is flying and working  properly unhook it and go fly. I notice a pattern it is usually on start up or shortly after they click on the "amp"they  wander off. Do you think a bunch of people in the crowd using cell phones might have had some thing to do with it ?On the telephone pole out side the fire station here    there is a high frequency signal devise emitting a signal 24/7 if there is a call the fire fighters push a button and all the traffic lights go green . you might have got jammed from a signal from the fire department it self? Just throwing it out there?If you get any crap from this there is only one way to take it. Face it head on  deal with it then move ahead.Try and have a nice day!

An other reason I would say a form of "Jammed" you made it to the first marker Ok on manual

I haven't looked at the logs yet, but I just wanted to say you did the exact correct thing as a pilot, IMO.  Instead of shutting it down and having it crash into people, you throttled up, got it away from people, then killed it.  

This is why I keep saying over and over that there should not be a "watchdog" or "killswitch" which simply kills it as soon as anything goes wrong.

what happened to the video ?

@R Lefebre How does the kill switch kill the copter? automatically over the crowd as soon as some thing goes wrong? or does the pilot operate the kill switch? I think I know what you mean it is just the way it was worded Have a Good Day!

Being uploaded right now, should be reade in a couple of minutes.

There wasn't a lot of space to put it down behind the building either

So sorry to hear about your crash, but good to know what no one was injured!

I was looking at the logs with Dan's log visualizer and your video at the same time to see if I could spot what went wrong.

I'm pretty new at looking at logs (after my own crash) but with the pitch I see in the logs, the quad should have returned to you but instead it kept going away from you.

I'm just wondering, is your camera on a stabalised gimbal or is it fixed to your quad. I ask because towards where it looks like you have trouble (1:55 in the video), the logs show the quad pitching upwards, but the video looks like the camera (and the quad?) continues to point downwards. 

My guess is fw 2.7.1 -  I had several times testing this where the copter would slide off in some direction and I would find the stick completely opposite - it was usually 3-4 min into flying and not apparent at takeoff.

Happily, 2.7.3 is a thing of beauty - I am approaching 100 mission runs without failure (well, some pilot failures):

The $  and time loss really sucks, but one great thing about the quad hobby is that you can rise from the ashes much easier than a model you spent hundreds of hours on or a TRex 600 life threatening crash!

Something that has saved me damage in my numerous crashes are the spring loaded legs on the x525 frame. I have seen it fall 20 feet to cement without major damage (except to my heart!)

Carl, some people have been demanding a failsafe system, onboard the APM, which automatically kills the copter as soon as anything goes wrong, with no input from the pilot.  I am a strong opponent to this idea.  In this case, it might have led to the craft crashing into the crowd.  This is why people operating these systems need to be skilled pilots, and the system is an aid to make things safer.  The system should not be used by people with no piloting skills, making them think they can fly, over crowds, etc.

Hey Ervine,
I don't have a stabilised gimbal under the quad, the GoPro 2 was hard mounted onto the copter.
I did about 3 or 4 flights with fw 2.7.1 before this one, in simple mode and in normal stable mode, without any problems.
I did not had the time to try to reverse the quad or try different modes as one would usually do on the airfield or free space. RTL was no option to, because I would had to let go the sticks to do the quad its job. If it was a firmware error, this would hurt the most, because of some bits and byted nearly destroyed someones health.
Hey John,
An error in the Firmware would be bad news, because that means I destroyed the copter for nothing. What I can see right now is that the gyros onboard the IMU have a positioning error of about 10-20 degree when I rotate the imu and but it bac horizontally. but this could be because of the crash.
I will investigate all the parts and post the results.

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