Quad rotor crashes into swimming pool...

My daughters and I have a custom-frame aluminum quad rotor that uses the standard Arducopter electronics and software. Last evening, in an act of piloting stupidity, I accidentally crashed  the quad into my swimming pool with a spectacular, high-speed, spinning splash. As soon as it happened, my heart sunk. I thought "I just ruined our quad. This is going to be a TOTAL LOSS."

 

We ran over to the pool. The quad was sitting on the bottom of the pool in four feet of water. To our utter amazement, the water was glowing with blue light. The quad was still on and functioning under water. All the LEDs were lit and acting normally. 

 


After taking half a second to get over my stunned disbelief, I ran into the pool, grabbed the quad, and pulled it out (hoping that a 11.1 volt LIPO mixed with a pool of salt water wouldn't give me a jolting surprise). 

 

"That's so cool, Dad, we invented a quadrotor-submarine!" my daughter said as I went into the pool.

 

When I finally got the quadrotor onto the deck, the lights were still on. I yanked the Deans battery plug, thinking I should kill the power ASAP. We took the quad rotor into the house and tried to dry it off with towels and a blow dryer. We then let it dry overnight.

 

This is a "salt water" pool, which means you add salt pellets to it rather than chlorine sticks, and then an electronic "Chlorintor" converts the NACL to chlorine. This results in a pool that is about 1% salt and a chlorine level of about 1.0.

 

This morning we inspected our quadrotor-submarine for damage. Again, I was expecting that none of the electronics would even power up much less function as designed. I assumed they would all be ruined. To our great surprise, we powered it up and it came on. Here are the details so far:

 

1. The battery was functional and doing its job fine, but it was wet and soggy, so we disposed of it and replaced it with a new one.  (No sense taking any chances when it comes to Lithium-Polymer).

 

2. The Futaba receiver comes on and appears to function normally. It locks onto the Transmitter and responds to commands.

 

3. The Battery Alarm comes on and appears to function normally.

 

4. Astoundingly, the ArduPilot Mega and IMU come on and appear to function properly. They boot up normally, show the normal lights, respond to the RC Transmitter, and power the motors. When I rock the quad back and forth, it changes the motor speeds, so that indicates the IMU board is at least alive and that the Arduino software is running on the APM. Obviously, we'll do more tests, but this seems promising.

 

5. The MediaTek GPS comes on, blinks the normal amount of time, and then locks on satellite signal. 

 

6. One of the motors runs fine (although it seems a bit hoarse in tone as compared to before, as if it's filled with salt particles or something). Three of the motors (or their ESCs) are twitching and beeping like they need calibration. They are all getting power, but they aren't acting normally. I'm not sure if it's the motors or the ESCs yet. 

 

7. I can't tell at first glance whether the Magnetometer and Sonar are functional. We're going to test those a bit later.

 

8. There were no cameras or telemetry electronics on board at the time.

 

So, that's the damage assessment at this point. We were amazed.

 

The next step is to go through careful diagnostics to determine exactly what is working and what isn't. It could be that certain components are coming on and appear to be functional but will have problems that aren't immediately evident. It looks like the motors or ESCs need some work or replacement. But other than that, I don't see any obvious damage.

 

I officially nominate myself as the president of the DIY quadrotor-submarine society.

 

My daughters have changed the name of our quad from "Flyer 1" (their original name for it) to "The Nautilus".  :)

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Replies

  • Reminds me of this video
    http://www.vimeo.com/10051940
    Is it real?
  • One is always at risk of water damage of some sort. 

    Would it possibly help to spray the electronics with some kind of protective stuff, for example "contact spray" or some kind of silicone or teflon or...?

    I have been fiddling with some boxes I have and thinking how I can enclose the APM in a water resistant manner for my winged plane without blocking the functionality of the barometer. On the Arducopter it is even more complex to enclose the electronics but not impossible. Anyone with experience of this?

  • 3692283416?profile=originalHi all,

    due to a mixture of ignorance, stupidity and overestimation of one's capabilities I lost my Arducopter on a FPV flight. See picture of how I found it hours later, two ESCs still beeping. Surprisingly (for me), corrosion already started heavily on all electronic components. I cleaned all parts carefully with a toothbrush and pure alcohol and let them dry for some days.

    Now the following happens when trying to connect to the APM using Mission Planner: With the switch in flight mode, I cannot get a Mavlink connection, it times out. Trying to connect in CLI mode with the Terminal gives me at least some output: "Init ArduCopter V2.0.4.7 Beta" and so on. Is that text coming from the APM? Trying to submit a command does not have an effect, no answer, I only see the orange TX LED blinking when submitting my command.

    Is there any hope?

    Thanks in advance for all input.

    Best,

    Johannes

  • Developer

     

    In the tests i did on the ppm encoder, i've checked for APM/IMU electronic robustness and it seems that it was electronically very resistant.

     

    So i'm not surprised to see that you survived a swimming pool test.

     

    Eventually non waterproff components like sonar and baro could have suffer from salt, but perhaps not. All other electronic components are waterproof.

     

    The major problem with salt water immersion is electrolysis. So it's better if possible to cut the power as soon as possible and clean with pure water. APM/IMU are protected with a water-repellent coating, this helps a lot.

     

    Radio components are more sensitive because they are quite often using very high impedance components (fet transistors). Be aware that your receiver could have suffered from this amusement. You could have a very reduced range. I tested this on a boat, loosing a portable VHF receiver in the salt water. Was not working after. It was only 5 secondes in the salt water and i couldn't get it work again even after careful cleaning.

     

     

  • I have landed in water as well. After rinsing it off I was able to fly it the next day.

     

    4th post in this thread:

    http://diydrones.com/forum/topics/ac-2-0-38-the-good-the-bad-and-th...

     

    Good luck!

    Niklas

  • Developer

    I've trekked out into the SF Bay to retrieve an easy star. I rinsed it with fresh water right away and the ESC died two days later. Try and keep that salt from eating at your solder joints.

    Jason

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