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!

Greets

Marc

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

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Marco, please have a look at

this post

There are several examples shown by the developing team how not to fly in public/crowded places. This flight was my first over a populated area, if I look at the videos shown in the thread, I think that the dev team should reconsider what advises they give to other people.

Please, don't get me wrong, you are absolutely right, it's risky to fly with four engines, but 6 or 8 engines don't change anything if the software or the board freaks out.

I think we all should think for a while what we are doing and what danger we accept in this game and how we should behave in public! Nobody knows the dangers of this aircrafts better than we do.

We should tell all the people outside that this is NOT just toying around, this is serious stuff, and it should be presented as that. Ok, that will not rise the ammount of orders, but it would show responsibility to what we do.

Ok, as actions speaks louder than words:

http://diydrones.com/forum/topics/wee-need-a-disclaimer

At least it's worth to give it a try.

John, I updated to 2.7.1 last week, directly from the MP. How in Hell can you manage +100 flights in just a couple of days?
Or did you install from the developer repositories way before it was out for the public?
One thing in general, do we have any alert function for new and important updates of the firmware?
Interesting question!
So Jason, how does the dev team generally test its programming? And what next, what are the steps before a new fw version is being published?

Marc - Unfortunately, I am one of those geeks who jumps on every release as soon as they come (I need to get a life!). I started 2.7.2 epsilon 5 days ago and now have 30 logs with 3-4 missions each.  I never flew 2.7.1 or 2.7.0 on missions due to the bugs.  I have countless mission logs with 2.6 which I thought was great but 2.7.3 leaves it in the dust.

It has been a long road, some versions worked, some didn't, but I really think we are now at a stable base platform. I have tested so many versions that I could tell 2.7.1 had probs right after takeoff.  With 2.7.3 I am thinking that ESC / motor / prop fail is much more likely with equally disasterous results.

I am curious of the conclusion - if you ever get one - but this is basically what I've experienced several times, it pulls harder and harder to one side, until stick input is unable to compensate, if I - however - landed, then take off again - it would be fine - for a while.

This is "leans".  It's due to vibration.  You need to work on board isolation and/or reduce the vibes from your motors.

Jason, good analysis.  I also usually do an in-flight sanity check of the Simple mode before I trust it completely.

yep, that APM2 ended up in the sea, you know, the salty thing.  - still - it was mounted on 4 rubber dampers.

Anyway - is APM2.5 any less sensitive to this ?

Trying to recall my timeline here but...  Yes, I think they made a massive improvement to "leans" on the APM2 after that posting.  I forget the details, but I remember there was a breakthrough change that happened.

I'm am currently flying a 3DR Quad, with an APM1, simply mounted using the blue vibration mounting grommets. It is about as vibey as it gets.  The props are cheap, completely unbalanced, and wobble on the shafts because the holes are too big.  I'm flying like this because A) I'm too lazy to fix it and B) I consider it a flying test bed.  If it can fly like this, then people should not be having problems.

Now, an interesting note...  I have discovered on my Helicopter, that the system can work fine, even in the massive vibration environment of a Helicopter UNTIL a ball bearing starts to go.  Soon as the bearing starts getting unsmooth, it starts to affect the APM badly.  This is particularly true of any of the higher speed shafts, such as the motor, or the tail rotor shafting.  It seems to have less problems with the main shaft and rotor vibrations.

So, multirotor guys, check your bearings.  

APM2.5 is exactly the same as APM2 in this regard.

For me, its sad to hear that simply less than one week not updating let me kill my copter. Well, I should have checked the listed bugs more often.

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