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Dreadful Crash

Discussion in 'Pro/Adv Discussion' started by Ardy, May 8, 2016.

  1. Ardy

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    Hello All,
    New user in this forum, Bought my P3-A abt 2 weeks ago, Been flying for years with cheaper models of helicopters and quad copters.....I had my eyes on the Phantom for years and watch it grow. Finally bit the bullet.

    In any event on my third fly something strange happened, I did the pre-flight checks and calibrations, all went OK started it and hovered to abt 5-feet and then slowly went to 20 and right at 35-feet or so the drone started to spin out of control and then Yessssss The Dreadful Crash. It was a sad seen..... The Gamble Broke the camera disconnected and broke from the arm....The shell seem to be OK, the antenna on the leg popedoff, any how you can imagine.

    With help from this forum I figured out to download the *.DAT and *.TXT file and started to dig in there. Looking at the files it seems the that right abt 25-feet it did a mode change for what ever the reason was(I had good GPS and Satellite count) and the motor obstructed, which I think it either seized and or stopped thus the spin and crash.......

    Reading this forum I saw several other threads that they seem to have a similar issue, In any event I am contacting the Dji on Monday to see where I can go with this...

    What I am Wondering is that if any of you who are more acclimated in understanding the either the log file or txt file any insight is appreciated......I will keep this thread open and will update as my communication advances with dji

    Date of Flight: 5/7/2016
    Duration: 1m57s

    Link to the files:
     
  2. RedHotPoker

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    Sorry for your unannounced sudden landing. Hopefully the logs will reveal what the cause was. Thanks for being positive in a negative situation. It can be gut wrenching, to see a loved RC hit the dust. But crashing is part of flying, even for the pros... ;-)
    You will be back and flying soon, with a refreshed drone and all.

    Please do keep us updated on the events as they transpire.

    RedHotPoker
     
  3. Roamer105

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    Go to this to healthydrones to see your flight: HealthyDrones.com - Innovative flight data analysis that matters
    Clearly a motor obstruction as you already saw. Since this P3A is new, I think warranty should cover it. Can't see any external reasons for motor obstruction.
     
  4. Ardy

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    Thanks for reply, Yes I did go to healthydrones.com. I also started experimenting with DashWear and Datacon to include Fly. all *.dat converters...... I don't quite understand why Dji don't have a program for the users to read the *.dat or TXT file, I am sure they must have one, because they also are looking at these files.....Oh well, its all new to me and I am learning......
     
  5. Luap

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    Checking motor details from the Dat file right before the altitude drop and crash you see that the load (green line) of the motor right back goes close to zero and CMD and RPM shoot up to 10000.
    That means prop probably came off which caused the crash.
    Was there a prop missing from motor right back when you picked the P3 up?
    upload_2016-5-9_0-49-1.png
     
  6. pilotpeter

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    Lauob what program were you using to view that file? It's the dAt file, right?
     
  7. CCDD

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    I had a similar issue 3 weeks ago. File a claim with DJI and you might get lucky like I did. PM me with questions.
     
  8. Ardy

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    Thanks for the reply........
    When It came down I could see all props, when it hit the grounds all was loose and parts were flying... It came in side ways and the motors were still running against the ground and the vegetation, I had to hold it from the leg and right then props flow away....found 3 of them but couldn't find one......
    I couldn't get Dashwear to work so I graphed it in Excel the motor speed Vs Motor Load.....This is from when the problem started right around 102500 ms.... from 0 to 102500 was all OK I will post one that has all the time series......
    Crash_5-7-2016_All.png
     
    #8 Ardy, May 8, 2016
    Last edited: May 8, 2016
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  9. pilotpeter

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    How are you all extracting info from the dat file? What app or program?
     
  10. Ardy

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    I know it is frustrating.....I had to roam around the forum for days just reading....give this a try
    DatFile.net/downloads
     
    vipercubic likes this.
  11. rene van der meer

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    Sorry for your loss.
    Strange that you did see all four props going down, but could not find the fourth prop.
    If it was still attached, it would probably shatter to pieces on impact, but the center piece would still remain on the motor.
    Loosing the prop would explain the crash. Are you sure it was not lost mid air?
     
  12. Roamer105

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    It may have seemed visually as if all 4 props are there while the quad fell down spinning wildly (as evidenced by the last few seconds of compass rotation).


    Sent from my iPad using PhantomPilots mobile app
     
    rene van der meer likes this.
  13. Ardy

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    In the midst of experience, who knows. May be I thought I saw them. the PS spinning could have had the visual effect that all of the props are there. It could have been that it came loose, it seems the evidence is pointing that way. Interestingly, one thing I know for sure is that I did tighten all of the props prior to lift off.......
    -------------
    Here is another strange event rene, day prior to the incident, I was having a similar issue but it happened very briefly, It came down almost as soon as it took off, fortunately it was so close to the ground that it didn't damage anything....So I stopped and started reading and roaming the forum....
    Motor Load and Speed.....
    5_6_2016.jpg
     
  14. Luap

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    upload_2016-5-9_21-24-27.png
    Nice charts!
    As you see there is no load on motor right back at the read square - that means prop flew off at the time where the arrow head is. Also RPM increases to 10000. Thats the RPM at which the motor runs when you have no prop on and apply full throttle(P3 applies full throttle automatically as you would see from the Motor CMD column if you plot it).
    After the red square you will note load increases. Thats the impact time into ground and motors are obstructed by the soil. Happens at around 6300ms. All motors load spike at right about that time.
    You should plot GPS altitude to verify the time at which the P3 hits the ground (or the accelZ(M/S2) column)
    You will also note that after impact there is is no load on motor right back again showing there is no prop on this motor.
     
    #14 Luap, May 9, 2016
    Last edited: May 9, 2016
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  15. Ardy

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    Thank You Luap, It sure looks that way,
    Hay not to burden you, can you give me your take on this.....in terms of experience this was the same the difference was the altitude and duration, This was a minute or so and may be 12-24 inches off the ground it was close enough that it didn't do any damage and all the props were in place....but it did start spinning .this was a day before the crash.....
    Also can you explain the MotorCMD? Is there a resource that explains the columns and thire intent and or meaning.

    The plot is the same Speed Vs Load.....Speed is the left axis and the load is the right axis....
    5-6-2016.jpg

    5-6-2016 - csv (10mg)
     
  16. BudWalker

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    Look here for info on the .csv columns.
     
  17. Luap

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    Not sure I follow. I plotted the control throttle column from your attached csv. Its 0 throughout except where you did the CSC to start motors and at end to shut down. So the "flight" you are showing is the P3 on the ground at idle speed.
    I.e. I do not see any throttle added to lift off 12-24 inches off the ground.
    You will also note RPM plots in your chart remains horizontal for all 4 motors after the motors start. This also suggests that you did not apply any throttle (or other stick movement). Furthermore, RPM is in the 1800 to 2000rpm range which is idle rpm. Hover is around 5000rpm.
    Maybe I misunderstand what you mean?
    Have you made any progress with Dashware?
     
  18. Bigfootbuilt

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    Luap, could you tell me what app you are using to generate these graphs? Thank you
     
  19. Ardy

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    Luap,
    First off I want to thank you, I am learning a lot in terms of aggregating the data and decipher what it means.......To be truthful its been a learning experience, One good thing out of this experience.....
    Maybe I got the wrong DAT file. But What I experienced was taking off for abt 12-14 inches and the craft started spinning.....I will look at the DAT files to see if I can find it.

    I do Have a question..... The Control Throttle is always is Negative? The Higher the number it dose indicates sort of like pushing on the gas peddle? What dose the positive number means......?
     
  20. BudWalker

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    The value for Control:Throttle ranges from -10000 to + 10000. If the left stick is all the way back then Control:Throttle = -10000, all the way forward it has a value of +10000, and neutral the value is 0. Control:Rudder, Pitch, and Yaw follow the same scheme. Information about these columns as well as all the columns of the .csv are documented and can be viewed by clicking here.

    For your "flight" at 12 to 24 inches you might be interested in the vpsHeight column. It should be accurate at less than 3 meters height. It's also documented here.

    I agree with @Luap. Nice work! You've become quite the .DAT expert in a really short time.