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Nearly crashed my drone

Discussion in 'Pro/Adv Discussion' started by ElGuapo, Aug 29, 2016.

  1. ElGuapo

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    Last Saturday was a beautiful day at the beach with the family, along with the family the bird came with me to enjoy video over the ocean waters of the Pacific. Weather conditions were clear blue skies with winds around 8MPH.
    As the day went by I sat with my tablet to program my mission in Autopilot, when I was comfortable with the mission I launched the bird in Autopilot. Total time for the mission was around 15 minutes and 10 seconds, for some reason I felt comfortable with this.
    The last point of the mission was for the bird to go out 1,500 feet in the ocean and pick up an altitude of about 175 feet to create a nice video effect with the camera pointed to where I was sitting with the RC. On the last leg of the mission my battery was almost down to about 25%, I started to panic. The bird was far out in the ocean and thought that I was not going to have enough juice to make it back.
    I immediately took manual control of the bird by switching from F mode to P mode and started to fly the bird back home manually. I was flying in the same direction of the wind, which helped quite a bit. I remember reading the speed in the App and I must have been doing about 27mph.

    I looked down to my battery level and saw that was getting close to "critical", my throat dried up. I started to think that once the battery reaches critical level the bird is going to auto land in the water. My thumb was pushing the lever to the forward position to make the bird come back to me as fast as possible. I finally see the bird getting close to me, I started feeling much better.
    Finally when the bird was very close to the shore I released the throttle to slow down but the wind was pushing the bird and it made the bird slide about another 10 feet in the forward direction, not sure if it was so much the wind but at the rate of speed I was traveling. The bird almost, almost hit parked cars and power lines. That would have been the end for my AC, perhaps after hitting a sign and parked cars the bird would have landed in a busy highway and possibly get run over by a car, such a high traffic highway.

    I guess what I learned from the experience is:

    1- Not cut myself so short on a windy day.
    2- The bird needs stopping distance.

    I have been thinking this whole time that I had left my thumb in the lever for another second this story would have ended in a crash.She is fine but I learned a good lesson.

    I hope this helps the rest of the phantom pilots in this forum.

    Oh I was shooting video the whole time. So here is a link:
     
    #1 ElGuapo, Aug 29, 2016
    Last edited: Aug 29, 2016
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  2. Amigorick

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    Whew !!! That was close to those power lines !!! Glad you didn't lose the drone !!!


    Sent from my iPhone using PhantomPilots
     
  3. ryantrax

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    Wow that was close!!! Good save :D
     
  4. ElGuapo

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    The whole time my heart was in my throat. I promise I will never do this again, especially on windy days. I guess the mission was fine, what was not factored in when I setup my mission was the weather/wind. The stronger the wind the more payload is = less battery.
     
    #4 ElGuapo, Aug 29, 2016
    Last edited: Aug 29, 2016
  5. WetDog

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    Rule of thumb while boating: 1/3 fuel load going, 1/3 fuel load coming back, 1/3 fuel load reserve.

    Murphy was an optimist.
     
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  6. ElGuapo

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    It is my fault, people in this forum have lost so many drones, one way or the other, to third party apps.

    One thing is for sure, I learned my lesson. For a moment I thought I was going to lose my bird..
     
    #6 ElGuapo, Aug 29, 2016
    Last edited: Aug 29, 2016
  7. WetDog

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    Good judgement comes from experience.
    Experience comes from bad judgement.

    :(
     
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  8. With The Birds

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    Try and plan missions so you have the over water or other areas where chances of recovering AC if it ditches are slim so they are earlier in the missiin where you have plenty of battery. Dont launch straight into the mission. Fly manually close.to your first waypoint so you get a feel for AC performance. Practice in ATTI. Quickest way to fly home if you have an issue.
     
  9. ElGuapo

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    Honestly I have never tried to fly in ATTI, didn't think about that. I have heard about it in this forum.
     
  10. With The Birds

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    Do yourself a favour and get some hours in atti. You dont want your first experience to be when you loose gps unexpectedly.... :)
     
  11. ElGuapo

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    :)

    I promise I will, do not want to lose the bird.
     
  12. Pharm

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    The third party app is rarely, if ever, the cause of someone losing their drone. It's their failure to understand how the third party app works and/or the limitations of it. For instance, most people using Litchi don't understand that when using waypoints, if the path is set to "sraight lines" instead of "curved paths", the drone will stop at each point and then start again. The time lost stopping and starting at each waypoint is NOT calculated into the estimated mission time, nor does it take into account the wind speed.
     
    #12 Pharm, Aug 29, 2016
    Last edited: Aug 29, 2016
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  13. Flipsonic

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    Can you please explain this further. Because when I have the mission on straight line, I don't experience the stop and start you mentioned. Or Maybe I've misunderstood what you said.



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  14. Pharm

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    I mentioned it because someone posted a little while back about the mission taking way longer than the estimate. He was set to straight lines. I wrote to Litchi support and they confirmed that it stops briefly and starts again at each waypoint if set to straight lines. Here is their answer from July 11:

    "It is correct to assume it doesn't take into account the stop time at each waypoint when using "Straight Lines" path mode. This can indeed result in bad time estimates especially with a lot of waypoints."

    Also, if all waypoints are set to curved paths and you add a new one between two adjacent waypoints, the bird will briefly stop at the new waypoint UNLESS you manually change the curve size of the new WP to some value above zero. Had this happen to me a few days ago. It very briefly stopped at a WP I added between two others. I increased the curve size of that WP and ran the mission again. No stops on the subsequent flight. The slower you're flying, the less noticeable the stop is. I was flying at 18 mph so it was noticeable and even more so when I sped the video up 2x. I would guess you're flying slow enough that you don't notice it.
     
    #14 Pharm, Aug 29, 2016
    Last edited: Aug 29, 2016
  15. Vertigo

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    Flying at top speed will not give you maximum range. If you're low on battery, you should fly slower, counter intuitive as that may seem (at high speed props and motor will not run at their optimal speeds, props will generate excessive drag,..) . Ive not seen any exhaustive or conclusive tests about this, but its optimal speed is probably somewhere around 10m/s. Faster if you are going against the wind, and even a little slower when you are going with the wind.
     
  16. With The Birds

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    Optimum speed is 14ms for max range (ie almost flat out).... if i remember right 14km for a 17min flight. Was a thread earler on this forum with a link to.some very extensive testing and calculations ro support findings.

    You have disregarded transitional lift and other factors. Hover and low speed is least efficient where most of your energy is applied to staying in the air.
     
  17. With The Birds

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    I have the link to the article. Cant find the original thread.

    long range drone DJI Phantom 3 professional
     
  18. Vertigo

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    Wow, excellent stuff! Although at first glance, Im not convinced his method of calculating propulsion power numbers are accurate for forward flight; it seems based on power measurement at zero airspeed. I know from planes this can be quite misleadingfor fast forward flight. As the airspeed speed increases, the load reduces significantly. On the ground I may measure 50A at full throttle, in the air this can be cut in half on some planes (while running at a higher rpm). I dont expect the effect to be quite that dramatic on a multirotor, but it will be a real factor.

    Still, his argument is more convincing than mine, so without actual measurements to prove him wrong, I'll concede :)

    edit: looks like he also ignores the negative lift generated by the shell at an angle, which could be quite substantial (edit bis, I think he does, he just calls it "downwards force"), and also likely a much more minor factor, the drag of the gimbal.

    All in all, quite interesting, but Id like to see some good real world data before accepting this as is.
     
    #18 Vertigo, Aug 30, 2016
    Last edited: Aug 30, 2016
  19. With The Birds

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    Simple.... check out the max range threads. Do a couple of test runs. I know more than once where i have landed with single digit % remaining (misjudged wind or got a little brave) where i would not have got home at 10ms.
     
  20. ElGuapo

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    I was referring to fly aways during missions reported by users, although fly aways have happened quite a bit using the Go App.