[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

  • Maybe you have a propeller not tight enough, or break slightly, or a connection breaks.

    Otherwise maybe a saturation of IMU or MC for vibration, lost of RC signal.

    Good look

  • Hi Roberto,

    Sorry to hear about your crash. I also had my fair share of crashes.

    Anyway, here is a good read about Li-Po Batteries. According to the loggings, your batteries are the cause of the problems.

    Li-Po batteries: http://www.mrpositive.co.nz/understanding-lipo-batteries/ 

    Here are the things that I would do if I am in your situation :

    1) Limit the components powered by your main batteries. As far as possible, your 4s should only power your motors, APM and receiver. Other components such as Video TX and RX, gimbal stabilization system or even LEDs should be powered by another battery. This is will maximize your flying time.

    2) Limit your flying time. I bring back my multirotor when battery level is at 55% to 50%. Just to be safe and also prolongs your battery life.

    3) Set your battery fail-safe. I'm not sure if you set it up but I set it for RTL if APM detects my battery are at 3.35v per cell. This way your multi-rotors motors won't suddenly cut off. 

    4) Get a battery checker.

    Hope this helps. I am not an APM wizard, but just to share. Still have lots to learn.

    Please don't give up on the APM ! Its features as compared to the DJI WKM is remarkable! Trust me, I been there. :p

    Cheers!

  • Roberto, if you have another 4s battery do this: charge just like you did last time or always, after that, take a voltimeter and measure how is the total and how is each cell, that should reproduce the problem as it seem both were the same.

  • On the bright side, you got some beautiful video before the crash. I had similar power issues like you on my first couple of flights, luckily I was flying low. If you try this again, try hovering your quad low until the battery runs out. Practice handling that situation, and make a plan for what voltage you will land at, giving you enough time to make it back down to the ground. Also, just accept that crashing is part of the hobby, and part of the cool stories you will have to share afterwards. I once got my quad stuck in a tree and had to beg the local fire department to bring out a ladder truck to get it down. It took me a few months to fix up my quad and get the courage to fly again after that =)

  • Developer

    The IMAX charger has a max input mA setting. Do you have this set correctly. Otherwise the charger will be only input a fixed amount of power. I am not sure what it is set as default and there is also a safety timer, that cuts in. see http://www.pololu.com/file/download/iMAXB6ACmanual.pdf?file_id=0J525

  • Roberto

    You'll be wasting your money splashing out for a NAZA without fixing this problem - you'll have the same thing happen.  I've been plagued with fall out of the sky failures over the last few months - it was a bad solder joint (in fact, several, and one almost broken wire).

    In your case, clearly your batteries have been discharged too far - chuck them out and buy a new one.  Resolder everything and check for any wire breaks.  

    The arducopter's performance is equivalent to the Naza, and despite me accusing it several times, it turns out that NOT once was it at fault.  Has always been mechanical/electrical failures.

    Persevere at this hobby, it's frustrating at times - I'll be posting a video shortly of the success I've achieved today with AC.

    Best

    Gareth

  • personally i thnk you were to ambititous. When i first started flying i practiced just taking off hovering and moving about a bit all under 3m. Then after a few days i got more adventureous and it was a few flights before i was confident my setup was working well and tehre would be no battery and other surprises.

    I broke my own rules one time when i started flying FPV and i crashed (flicked the wrong switch flight mode and fell out of the sky) from about 15m high and like you smashed a few things. I always take small steps because gravity is harsh.

  • Sorry to hear about your loss! I would recommend a good little Turnigy Accucel 6 (20ish bucks). It works great. Not to beat a dead horse but I think my 6s 22.2v batter is fully charged above 25.2V's. (4.2v per cell x 6). Actually a funny story on that thing. I discharged that battery so bad that a charger wouldn't even recognize it, I brought it back to life by telling the charger that it was a different battery, dumped as little amps in it as I could until I got it up around 18ish volts, then it was being recognized as a 6s. Ran some IR tests on it, I think overall it was like 14 or 18. One cell was pretty up there in impedance. But the battery still worked, until it died in a brutal crash. I have since discarded of it.

    Although I am super new to this hobby. Batteries are a different beast all together. I spent a good 3 or 4 hours just reading different lipo breakdowns, specifications and best practices, it is the most important part of your entire setup.

    I would buy a cheap tri copter frame and try to put something cool together, assuming you still have 3/4th's working components. That would be the best route.

    For my new setup I ordered these:

    http://www.hobbyking.com/hobbyking/store/__18588__Hobbyking_2_8S_Ce...

    Fairly cheap, even though it seems kind of redundant, can't be too safe with my investment can I? I will be using this along with the power module on my apm 2.6. I crashed my jet hard core a few days ago, had a really good laugh about it, then rebuilt it. Just like the good commander said in Galaxy Quest, never give up, never surrender!

  • I never discharge the batteries below 3.7 v per cell (No Load) that is probably about 3.3 in the air. After that you have a permanently damaged battery. 

  • With that charger, you need press start button keeped down 2 times with blinking Amps, then Volts. Then charging begins...

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