The luckiest fly away ever

Hi everyone,

First of all: Don't hate me. I know I should have been more careful and took an unnecessary risk that could have caused a lot of damage and was pretty dangerous. I'm well aware I need to work on my impulse control and take things one step at a time so I don't risk myself and others. I am not in any way saying that this was okay to do and I have learned my lesson.

Yesterday I had my 3rd flight with my first ever quad. It's a 680 HK plywood frame with 610 Turnigy multistar motos, Afro ESCs 30A and 12x45 CF props. I'm running an APM 2.5 (onboard compass) with Arducopter3.1.5, Ublox GPS and 3dr radio telemetry. Powered by a Zippy 5000Mah 4S battery.

The first flight, I had a problem with one motor mount that resulted in a low altitude crash. Broken arm, quick fix. Second flight was very successful. Tested Alt hold, Loiter and RTL and autoland. All under a lot of wind (it's always windy where I live). All modes worked great with ZERO tuning. What an incredible piece of software. I got confident, too confident.

On the 3rd flight I decided to have my girlfriend come out to check it out. I live in a block with 5 8-story buildings. I put the quad in the grass between my building and the next (about 25 meters between them, 27 yards). I took off, still very gusty, but the quad was fighting the wind like a champ. Very stable on Loiter. I took it around for a while and decided to show her (I know...) the RTL. I said "Look, I can flick this switch and have it come back and land all on it's own!" Well...

The quad gained altitude (so far so good, it's meant to go up 15m) then it started getting closer to my building as it climbed, I got scared. It misses the bulding from the top by just a little and I lose sight as it goes over the building towards the highway. At this point I'm flat out panicking. On the other side of the buiding there's a highway and on the other side suburbs. I'm panicking here, so I'm not sure at this point if I left it on RTL or changed it to loiter. I didn't have a chance to download the logs yet. I ran around the building and couldn't see it. A neighbor saw me with the transmitter strapped to my neck and said he heard something "clacking" in the roof of the building. I run up a hill that is slightly taller than the building to look at the roof, no sight of the quad, but I can't see the whole roof.

I go back to my apartment, after some googling I find the number for the manager of the complex. Call him no answer (it's around 7:30PM at this point). Call the super, no answer. Take my tablet with the 3dr radio, go the the tallest floor and see if I can conenct to anything, nothing. I look into the mailboxes (here the managers are usually also neighbors who volunteer), find the lastname of the manager, buzz on his door, he tells me only the super has access to the roof, but he only comes over once a week. I'm starting to think I lost about 1K of investment and countless hours (that's still better than having the quad land on the highway and cause an accident).

I go to my balcony that faces the highway side and once again try to connect with the 3dr telemetry and the tablet, no dice. That's about 20 min after take off (I guess, hard to keep track when you're panicking). While I'm in my balcony I hear a beep from far. I just grab my tx and throttle (no idea why I thought that would help) I look up AND THERE'S MY QUAD coming from over the building, HOVERING THERE ABOUT 400 FT UP! Then it wander towards the builing and out of sight again. I run towards the other side and see it hovering right over a factory in the distance. It's loitering, but being punished by the wind. I do by best to not shake to much and bring it over closer. I land on the grass, run to it and to my surprise the thing is INTACT. The cell checker (life saver: http://hobbyking.com/hobbyking/store/__18588__Hobbyking_2_8S_Cell_Checker_with_Low_Voltage_Alarm.html) that I had on the frame was buzzing like crazy alarming that one cell had reached 3.4v. Other than that, the quad was perfect.

I still have not wrapped my head around what happened. The quad was out of my sight for around 20 minutes. Nothing broken, not even scratched. My best guess it's that in a panic, I must have switched it back to loiter and it just hovered there over the roof for 20 minutes in a place I couldn't see from over the hill. Then the cell meter started buzzing (the thing was LOUD) I gave some throttle and the gust pushed it to sight for a moment before the quad tried to get back to where it was.

I still can't believed I recovered it in PERFECT state. And it doesn't seem possible that that setup would stay hovering for THAT long. Either way I'm thankful and HUMBLED. I'll never fly in auto or RTL anywhere NEAR people and property. And I'll always be ready to switch to stabilize when I do.

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Replies

  • Yes, you are lucky but I agree with those that say we learn from our mistakes. Here's to the next flight :)

  • Nice, lucky story! 

    Could it have triggered the gps glitch failsafe since it was flying between buildings?

  • T3

    When you got to the part with it drifting towards the building, I thought the story was going to end with the copter drifting away through your open window and onto the coffee table (THAT would be the luckiest flyaway ever.)

  • Awesome story, thanks for sharing it. We've all been there. I had a similar recovery story when I got my first F450 going.

    Short version: lost sight half mile away, thought it was lost... was hopping in the car to go pick up the pieces and my 4-year-old shouted "DAD! I SEE YOUR HOCKERPLANE!" Faithfully flying home. We still call multirotors "hockerplanes"

    Moral: go slow, test everything thoroughly. Push envelope gradually and give yourself lots of space and altitude to correct.

  • Crazy story, glad everything turned out ok. Please post the log files! I'm curious, why didn't you switch to stabilize when it was clear there were problems with gps navigation? Were you not confident of your ability to fly that way, or did you just not have it available on your TX easily?

  • Wow Hugo, this a epic flyaway story!

    I'm very, very curious about this issue, what really happened.
    Flying with fixed-wing aircraft I'm had just one freaky event.
    Ardupilot only give me great moments!

    Did you posted it in a Brazilian forum?

    Thanks and good luck!

  • The moral of the story here is:

    • Learn how to fly in an open area
    • Set all the failsafes to act accordingly
    • Set your mode switch to east to remember settings
    • Use a tablet/phone/laptop for location telemetry
    • RTL Home is set when you ARM. Verify by flipping to RTL mode after takeoff to confirm the correct location is locked.
    • Always be ready to flip to stabilize mode if it is not doing something automatically correct!
    • Always be able to fly in stabilize mode!!  It is not easy. Learn that first.
    • I thought the moral was "never show your girlfriend your copter." ;-)

  • Awesome share. Thanks. Just wanted to add that because you will get good advice, maybe some negative feedback, but I think people should always be encouraged to share mistakes - especially when there are things to learn. Ta.

    • I wonder.... Because you were between the buildings, the GPS (the location the copter thinks it was) was a bit off.  Had its RTL point set at the coordinates of your building.  So when it RTL to the spot it goes, then it starts to descend.  It descends onto your roof which is not the correct altitude so it "thinks" its still in the air and goes to a really low throttle setting while sitting on the roof.  There it sits for 20 minutes.  It would still make corrections back to level if it was getting blown over, still be fully operational, just trying to descend back to the take off attitude!  So you grabbed your radio, freaked out and put it loiter and gave it throttle.  Well Putting it in loiter would override any RTL failsafe that may have activated and put you back in one of the manual control modes.  Raising the throttle over half would have started a climb regardless of altitude.  The extra power required by the motors and resulting voltage drop causes your cell meter to start alarming.  You look in that direction and your quad is hovering there or in a slow climb in loiter/stabilize or whatever mode you had it in. In stabilize it would have drifted with the wind horizontally like you said it was doing. Only way to tell for sure is to download the logs and check to see how long it was or was not descending in RTL mode!  Either way really lucky!  My oopsies never turn out like that.

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