[VIDEO] 2 Different multirotors crash on first flight

Some time ago I opened a post to understand why my Hexacopter shut down in the air, and crashed from 30m, resulting in considerable damage (2 engines, 4 arms, 1 gps, the landing gear and it's gymbal with servos, MinimOSD, etc). It was its first flight.

I love the community here, and the wonderful support you can get. Graham was kind enough to look at my logs and told me that it ran out of battery. Well, I thought, when I started the flight, the Mission Planner told me I had 52% of battery left, but it crashed after less than 2 minutes. Therefore, I guess it's the current sensor that plaid a trick on me, or I don't know what else to think.

So, the first hexa's frame being heavily destroyed, I bought a Quad frame, used the components that were still intact, and I happily assembled a second rotor.

Here's the video of it crashing. Yet again, on its first flight. As you can see around minute 2:08, it starts behaving erratically and at 2:32 it simply shuts down in the air. After the crash, you can hear the ESC and motors rebooting. Oh and -yes- this was a fresh fully-charged battery pack.

FYI, I:

  • balanced the props
  • calibrated the ESCs
  • calibrated the gyros and compass
  • calibrated the PIDs using Dave C's method
  • set the failsafe to RTL if current went under a certain level

It crashed while in Loiter mode.

I think I'm done. I'm either too unlucky for this hobby, or the Arducopter is a little too experimental for me to afford its costs (I've spent $3,000 on this, everything included), and I'm saddened about this. Too much effort and money for two flights on two different machines, both crashing on first flight.

Any pointers welcome?

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Replies

  • I had an issue like that on my TRI and my friend had a problem like that on his quad.... We finally removed the CHEAP HOBBYKING BULLET CONNECTORS.... 

    Im not saying it is 100% the problem but on  the cheap bullets the "prongs" rotate around the pin and that produces a less secure connection...  

    Its a little cheap insurance to upgrade your connectors if your having power losses.

  • Oh man, that's really unfortunate and real disincentive to fly again! i fully empathise.

    Try just building a quad as cheap as you can before "moving up" into FPV, OSD's etc. It keeps it cheap and simple to begin with until you're familiar with the dynamics.

    Also...use telemetry :-)

    I use Spektrum telemetry, which is great  because the battery level can be customised (i set mine to 3.7v per cell), and it beeps on the Tx when it hits that (I have poor ears and a loud quad so dont alway hear the onboard beeper). I means I have 2 minutes to land to stay above 3.5v (and avoid permanent battery damage), and to ensure stable flight. I also discovered the expensive way of the low voltage brown out scenario due to the $1 battery volt sensor being set too low...:-(

    Setting it at 3.7v when under load means it ends up being around 3.7 on the ground too after you've done the landing, which is ideal.

  • I want to piggy back on what the others have said and share my own noob experience. I have a TBS as well and I've spent the last few months trying to perfect everything and I'm getting there. In the beginning I had a problem with losing control and traced it back to a bad solder joint that was causing me brown outs mid air. I've been through 4 arms 2 motors and countless props until I found the problem. I would retrace your solder points on bullet connectors and the battery connector. Also I don't power my board at all from ESCs. I use a UBEC on the input side to power the APM. This really sounds like a brown out like the others said.

    Lastly, you have a beautiful flying location. Good luck the learning curve on the APM is steep.
  • Sorry for your crashes. But: One of the great things about rotorcraft is that test flights can be carried out at very low altitude over something soft, like a field of grass. It is a fundamental mistake to not use that capability on a maiden flight or whenever new hardware, software or settings are first installed in these complex machines. You would have lost little or nothing had you followed this fundamental procedure. I never fly higher than maybe 3m or over hard ground until I've thoroughly wrung out a machine. It's saved me a whole lot of time and money over the years.

    It is a further mistake to jump right into autonomous modes. First get the model flying properly and comfortably in manual mode and then start trying altitude hold, loiter, RTL, etc. methodically, one at a time.

    Also develop and use a preflight inspection/routine.

    As for the specific cause of this crash I have no real idea, but I don't like the sound of this quad, it sounds labored like something is maybe tight?. I wonder if a motor seized when it got warm (which could explain the first crash and maybe the apparent low voltage..)

    In any event, you might reconsider quitting - you can't really blame the hobby for your "luck" or the expense of these particular crashes.

  • I have had a similar crash with a Naza controller, I eventually traced it back to a faulty deans plug ( which I had overheated when soldering) the contacts on the connection were bad and under the vibration ( even with balancing props etc) it developed a bad connection and the added resistance made the battery level sensor read a low voltage and basically shut the system down. In your video the esc's rebooting would point me to believe a similar scenario.

    Don't give up yet, I had 4 bad crashes on 4 new frames within a month, these systems are not fool proof and the smallest of things can make the copter/plane fall out the sky.

  • Any Logs you can post? The wizards here will need them to see what is going on.

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