Iris+ Random Crash In Flight - Lost In Water

Hey DIY Drones,

This is my first post here, but I felt I would share my story and log with the community. Today I was out for a rather routine flight of my Iris+ from 3DRobotics that included an Auto Flight followed by some manual flight in Loiter mode directly after. No heavy wind or outside weather factors to worry about. A nice 70 degree evening here in St. Pete, Florida. Normally I fly the Iris+ with the Tarrot 2D gimbal and a GoPro but thankfully today I did not. I was getting my flight plan ready for a filming I was planning next week and was getting down the flightpath before mapping out the angles of the shots.

After flying in auto mode for the duration of my flight plan, I took over in loiter mode to do a short flight around a fountain I planned to shoot. I had just had the aircraft fly the same path in auto mode and I like to practice my flights manually incase I have to assume control in the middle of a shoot. About halfway through the maneuver the Iris+ started to wobble and descend like it was losing power suddenly. I kicked the throttle to full power and directed the drone away from the water (knowing a crash was almost imminent) but the drone failed to react to the controls and crashed in the lake I was flying over. About 20 feet from shore too. *Insert sad face* The drone now sits at the bottom of the lake in about 10 feet of water. I was unable to recover the aircraft today but and hoping to in the morning. 

Attached is a link to the log of the flight. So far looking at the data I cannot see anything to explain the sudden loss of control. The only thing I have really notice was a drop in battery voltage at the end of the flight, but I am unable to tell if this is because of the loss of the aircraft or there really was a sudden loss of battery voltage. The HUD never told me I had less than 70% battery during the flight and even so a loss of battery should have caused a return to launch. 

If anyone out there has idea what might have caused this crash, I'll take any input. With all luck I will recover the aircraft in the morning, but with the craft sitting in 10 feet of water for around 18 hours I am assuming a total loss. Sad. This craft seemed so stable in all other flights I've done with it (30+) and it was becoming a workhorse for me. 

Thanks to any who help! 



2015-03-28 19-09-14.tlog

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  • Justin, Sorry to hear of your loss. As for the unit being any good after a night of soaking with power applied, I am guessing it will be a goner. Power applied while in water is what destroys electronics. If you have some luck on your side, take 90% rubbing alcohol and spritz and spray it on the electronics. Use a toothbrush to clean anything that is white or corroded. Use a dental pick to clean between posts that have any corrosion, then start up your oven. Place it on 150 or the lowest setting (as long as it is not 175+). Put only the PC board(s) on a cookie sheet and place it in the oven. Either throw the lock handle or place a spoon in the door so that the moisture is allowed to escape. It may take 30 to 50 minutes to completely dry the board that has been soaking that long. Good luck.

    •   Thanks for letting everybody learn from this event.  It is almost destiny for flying machines to crash given the chance.   I find a lot of RC flying is minimizing risk and managing trust.  Batteries seem to be the most fickle of technologies involved.   It certainly is possible to recover the vehicle but keep in mind even if you get it flying again you will have a period of time before you can trust it again.  Any crash can result in something being marginal.  Allocate some time to gain that trust.  You may need an alternate vehicle if you are making your living this way.  Good luck and all the best.

  • Did you recover the Iris? 

  • Hi Justin:

    Sorry to hear about your misfortune.  I am still very much a newbie and hope you can post a good follow up.  I learn so much from you guys about "reading" and interpreting the logs.  I'm gonna download yours and see If I can find the info you are talking about. 

    What is just as unfortunate is to see such negative comments and personal attack on your character.  Completely uncalled for Mr. Fletcher.  

    Good luck Justin...keep us posted


    • Developer
      The lesson learned here is not to start flying with a battery at 10.5V. The question remains as to why the mistake was made in thinking the battery was fully charged.

      A dataflash log would give more info.
  • Developer

    The battery was at 10.5V (3.5V/cell) at the beginning of the log (not fully charged as thay would be ~12.6V (4.2/Cell)). I have battery failsafe trigger at 10.5V. When nearer 3V/Cell there is not much energy left in a 3S LiPo and the voltage will drop fast, getting exponentially worse, like falling of a cliff

    There are two measurements I use when flying. The percentage of the battery used from the moment it is plugged in. And the battery voltage. The battery voltage of 10.5V always overrides % figure. If the battery is unplugged and replugged in the percentage figure will reset to 100%. It does this since we cannot tell a slightly discharged batteries capacity as the discharge line in non-linear and different for each battery make/model/date of manufacture etc.. (we need smart batteries for that) 

    If the battery  is not living up to its capacity anymore, 10.5V warning will come early, and there is then still time to land.

    From the TLOG it reports in the HEARTBEAT message that the system_status has gone from 4 to 5 i.e. MAV_STATE_ACTIVE to MAV_STATE_CRITICAL it can still fly when that change happens, just its running out of time. I'm not sure how Mission Planner (if you are using Mission Planner) alerts you to that state.

    It maybe a good idea to warn users of batteries that are not fully charged when plugged in in the GCS, and better reporting of the overall system_status as the autopilot knew that it was in failsafe territory.

  • Ouch. Sorry to hear about your loss and hope it can be recovered. 

    Definitely pull the memory card and get the more detailed logs to analyze. The memory card should be fine if it is just 24 hours. 

    From the Tlogs it looks to me like a low battery voltage made the IRIS crash. I see it hit a fail safe prior to the crash. Did you select RTL or did it hit a voltage fail safe and then enter RTL?

    It is then swithched into Alt Hold and to Loiter where the voltage drops to a low 8v value before the crash. At 8 volts I do not believe the battery would not have the power to keep the quad flying. 

    • It hit the failsafe on its own but I did not switch into Alt Hold or Loiter right before crash. From what I can see the logs show the voltage fall of but it's almost like the quad thought "to low battery RTL" and then "no wait I have more" came out from it and then crash. Once I heard it hit the RTL I was going to let the quad come back home like I have countless times and then I hear "Mode Change twice" and then Boom - water. Not arguing the battery voltage. It was so fishy (pun intended) what it did that I just started looking at the log of the voltage. 

  • Dude, you need to get a clue and apply a lot more rigor in you flight safety. First off, you location is very irresponsible for a pilot of your low time.

    You took off with a very low battery voltage, it flew the mission and when it was almost done it went into battery voltage failsafe.

    It was all most done landing at home when you switched to alt hold then loiter and took it back over the water. It went into failsafe again but now it was too late. The voltage curve fell off a cliff and you machine dropped like a rock. Lucky for you it was not on someones windshield or head.

    Did you even replay the tlog ? Graph your voltage and you will see.

    You need to be a lot more aware of everything on your copter. Battery voltage is the most important.

    I would say better luck next time, but if your smart, you won't depend on luck next time.

    • "but if your smart"  ----  *you're

      Dang, Greg sounds like he's mad at you like you lost HIS drone!  

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