A little over a year and a half ago, I bought a 3DRobotics Iris+. Above are some details of the custom mapping rig I created for it, and at the bottom is a short compilation of some footage I took with it. Unfortunately, just a few months after I got the copter, I learned a very unpleasant lesson about lithium polymer batteries. I had just completed a mapping run of a property the day before, and had gotten the batteries at least two volts below the "discharged" threshold. I had just received a shipment of FPV gear and wanted to try it out, so I set up and launched the Iris at about eight or nine at night. After flying around for a while, I noticed the voltage dropping a little faster than normal, so I started bringing it back to my position. As it came back it kept dropping until it was about ten feet off the surface of a lake near my house. And then it became unresponsive. I got to watch helplessly as it slowly descended into the water and sank below the surface, it being to early in the season to have the boat out of storage. The next day we had to leave on a vacation, so for the past year and a half I have been working on retrieving the drone (which I am happy to report had a 3-year warranty taken out on it so if I retrieve it I'll be able to recoup its value).


So far, I've tried a few different methods of retrieval:

  • When we got back from vacation, I purchased a large magnet, affixed it to the end of a pole, and tried to sweep the bottom. Unfortunately, the last GPS coordinates of the drone are in about 20 ft of water, and the pole had to much give to feel any attraction.

  • This last winter, I borrowed my uncle's ice-fishing camera and drilled a grid of about 100 holes in the ice above the area, dropping the camera down the hole and doing a sweep. Although we had a few false alarms, we came up empty.

  • Most recently, I obtained  a PADI Open-Water diver certification, and me and my buddy have been conducting search circles with a fixed center affixed to the bottom (our lake is very silty, and you have to have a point of reference or you'll get lost). We've been searching nearly every weekend this fall, letting the visibility get better as it gets colder.


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I will update this page when I am successful in retrieval

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What I learned:

  • When flying around water, it is of utmost importance to have a drone that floats

  • Lithium polymer batteries are great for quick discharge, but are also very sensitive and need to be babied

 

Improvements for the future:

  • I need to train for emergency situations, e.g. which direction to fly when losing voltage (I flew towards my position rather than back over shore. Just like in the aviation industry, emergency situation responses need to be automatic

  • If I get another Iris+, I'm going to put a few short sections of pool noodle over the long legs so it will float in case of a crash

  • I might add some sort of radio beacon on the UAV so I can find it easier if it crashes


This is a compilation of some footage I took while the ice was still on the lake, and includes my first crash into a tree due to a absolute versus relative height error when I configured an autopilot mission.