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Help! Inexplicable Fly-Into-Building Crash on Inspire RAW running Litchi in VR Mode

Discussion in 'Inspire 1 Help' started by CFAN4, Sep 17, 2016.

  1. CFAN4

    Sep 14, 2016
    Likes Received:
    Hi Everyone

    It's a pity my first post here is a Crash Investigation! But I'd love to know what I did wrong!

    Since I had to travel with my Inspire RAW to another city for a film shoot, I decided to fly the drone at home (outside of course) to run down the batteries to safe levels. Since I was flying, might as well get some practice time in on VR Mode, because this shoot would be the first time I'd be flying FPV on a professional shoot.

    Everything goes fine, it's all working like a dream. I have Gimbal head-tracking on and Aircraft Head-tracking off. And I'm essentially hovering, testing out the range of movement on the gimbal with head-tracking. On the RC, only my left thumb is operational, going up and down on altitude. My right thumb is OFF the stick.

    Suddenly, I HEAR the aircraft moving laterally across. I rip off the VR and look up to see that my Inspire 1 with the Zenmuse X5R mounted on it, is ACCELERATING, straight towards a building. I know the dangers of flying near a building, I have flown in this very spot many times before. It's airspace I'm intimately familiar with - being right outside my home - and I have never had problems here, except one time I had a near crash when GPS signal was suddenly lost during a reasonably stiff breeze and I barely avoided a crash by pulling off a pretty hard landing. This was when I'd just got the Inspire - months ago.

    But I was less used to FPV, which is why I was being extremely careful, keeping my right thumb totally inactive and merely hovering, ascending and descending, testing out the gimbal. And yet, somehow, it accelerated. I'd really want to know what happened.

    A little context, just before this flight, upgraded both aircraft and RC firmware (FW_V01.09.01.30) - successfully.

    Immediately after that, I had a bit of trouble with magnetic interference at a spot I've never had any. Compass failed calibration twice. Moved to a different location, recalibrated. Worked fine. That's where I flew.

    And it all came crashing down. The aircraft flew into the building, and fell straight down. The basic airframe seems fine, that is to say, unbroken. It's certainly bent somehow, something has twisted somewhere, and I'm hoping it's a joint, rather than a beam!
    The camera, again, the heart of the camera - and its lens. they seem fine. The ND Filter is cracked. But the gimbal is in pieces.

    So now I'm praying that the damage is recoverable, and not totally unaffordable. But more importantly, why? Why did it crash?

    Here's my HealthyDrones Share - HealthyDrones.com - Innovative flight data analysis that matters

    DroneLogBook gave me better info when I uploaded the same logs. Turns out it was hovering fine, and then suddenly, turned and accelerated straight towards the building, going from 1.2 m/s to 2.47 m/s in a matter of 8 seconds. In a straight line!

    Unless I'm reading it wrong, the aircraft lost neither GPS nor Compass during this flight.

    Does anyone know what I did wrong?
  2. Mad_angler1

    Dec 9, 2015
    Likes Received:
    Sorry that sounds a bad one.

    A question, is there any chance DJI Go was open with Litchi in the background ?

    I would also open a ticket with Dji and get it sent in and let them look over it, the HD log just looks normal.

    What country you in ?
    #2 Mad_angler1, Sep 17, 2016
    Last edited: Sep 17, 2016
  3. CFAN4

    Sep 14, 2016
    Likes Received:

    I'm in India, in Mumbai. The way it seems to work here is that the dealer I bought it from is also the authorized service centre. I'm back in Mumbai now so I'll be taking it I to them - dann weekend's in the way.

    I'm certain DJI Go couldn't have been running in the background - as per Litchi's instruction I Force-Closed it.

    My first question remains what happened. Why did it suddenly fly in one straight direction. Is that typically what happens when GPS is lost and it switches to ATTI mode? Because that happened once before and almost crashed the drone. But I've flown indoors in a studio in ATTI, and while it drifted like crazy with every gust of the AC vents, it didn't shoot off in one particular direction.

    Plus the logs say GPS was never lost.

    The bigger question of course is whether it's fixable and affordably so! But even if I do get it back, if I don't know what went wrong, I don't know how to fly safely.

    Oh, one thing I didn't mention - there was a minor incident last month. I didn't realize how strongly the wind was reflecting off the side of the house I was near while landings and as the wind switched directions, the drone was pushed back just far enough to touch a leaf from an overhanging bush, fell about a foot. Props broke, two motors got wrenched out and had to be replaced. But the techs test-flew it, and then I shot with it for over a week straight, in all sorts of conditions, with no problems except one little hiccup getting into travel mode, which resolved itself in a couple of restarts.

    Now I'm wondering if there was a lingering fault left over.
  4. The Shadow

    Jun 28, 2015
    Likes Received:
    Not an investigator and probably not a cause but I am very leary of transmission loss and activation of Return to Home! Also even today I am practicing switching to a manual mode and emergency up actions as it seems this is where most clean air is and then you have a chance of signal gain or saving your aircraft. When I started with the old Phantom I would just go to the ground as fast as I could as it would do what your saying all the time. Did you calibrate your compass? Silly question maybe but it is as important as the GPS lock. Will be following this as these aircraft are not cheap and they are fragile compared to the Phantoms.
    Your craft looks to be a simple alignment of the starboard side. If you loosen the screws the shaft will rotate. Opening it up should show you the original alignment point (which is important). The gimbal camera issue is a trip to the dealer (might as well get the craft checked out by them since you will need to go to them).
    I am having issues with the DGI app and AutoPilot as the DJI app does not close very frustrating.
    #4 The Shadow, Sep 24, 2016
    Last edited: Sep 24, 2016
  5. 2nd2non

    Jul 26, 2015
    Likes Received:
    Orange County, California
    Did you perform an IMU calibration after firmware update? I've personally had (and others reported on the forum) stability issues sometimes if this step is skipped.

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