My number came up yesterday (crash!)

Discussion in 'Cinestar 8' started by Steve Maller, Oct 20, 2014.

  1. Steve Maller

    Steve Maller UAV Grief Counselor

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    Well, after hundreds of successful flights over the past year with my big X8 copter, I had my first crash yesterday. I wanted to share a couple details here for the community's sake.

    First of all, I was operating in very damp conditions (very low and thick fog) but I was so excited for the opportunity to fly at this event that I let my enthusiasm get the better of my judgement.

    Secondly, I was exercising my usual caution regarding a safe takeoff/landing zone, and an escape plan (which saved me from lots more trouble).

    In the video below and in the GPX file, you'll see the copter go into a serious bank before hitting a tree. That was me ditching when something caused the copter to bank badly to one side. I cut the power at the last second before impact.

    The copter sustained a lot of superficial damage (two broken CF booms and several shattered props), but fortunately the MōVI came out almost unscathed (a few scratches) and my GH4 and 12/2 lens were fine. It took a while to collect the copter, as it went down in a very brushy area, and thank goodness for TECNU (keep it in your kit!) because it was covered with poison oak (yikes).

    Anyway, my preliminary diagnosis of this crash is pilot error. In the limited visibility I believe I lost orientation and zigged when I should have zagged, and that resulted in me overcorrecting, which in turn caused a bit of panic, and resulted in my ditching. I've looked at the video and the GPX file, but if any of you see something in there that is cause for a different verdict, I'd love to hear it.

    Vimeo password is "oopsie"
     
  2. Ozkan Erden

    Ozkan Erden Distributor

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    I also think that's an orientation and not being calm issue:) No damage other then the copter itself, that's the good news.
     
  3. Ryan McMaster

    Ryan McMaster Active Member

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    Ouch, That was pretty damn close to the 101! I see in the file there was a point where you hit a pretty high throttle is that where things went bad?
     
  4. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Hooboy....better add one to the score for magnetic trees. Sigh. Who's gonna be your designate Grief Counsellor? :)

    It's also possible that the moisture may have temporarily killed a MOSFET. I'll have a look at the GPX file right away.

    Andy.
     
  5. Philip Lima

    Philip Lima Member

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    Sorry to see this! You did well by hitting those threes though, I think that may of saved your Movi and camera. I'm not nearly as much of an expert as you are... But having lots of experience flying in similar wet and foggy conditions(living just down the coast from you), I will say that keeping orientation can be extremely difficult in those conditions. I've had quite a few close calls with my quads while filming surfing in thick fog. The shots look amazing, but I've come real close to loosing a couple of them in the waves from heading the wrong direction in a hurry.

    I'm not sure it's correct to say but my general rule is that if you're giving input to the copter and it is not responding as you think it should, let go of the sticks just for a split second and flip into PH(if you have it). If it still doesn't do what it should, count your losses and try to guide it to a softer crash landing. I've done this once with the Cinestar 8(loaded with Movi MR and RED Dragon), I was flying LOS about 600ft away and at less than 10ft AGL and lost orientation, it definitely got my heart beating, but I was able to figure things out and get it back in one piece.

    Good luck getting her re-built and back in the air!
     
  6. Steve Maller

    Steve Maller UAV Grief Counselor

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    Actually, the 101 (the approach to the Golden Gate Bridge) was at least 100 feet or so above where I was flying, so I wasn't actually very close at all. The high throttle may have been AH and PH trying to compensate for the extreme bank that I dialed in, and why I eventually cut the throttle and let it settle into the underbrush.
     
  7. Ryan McMaster

    Ryan McMaster Active Member

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    True, We shot a commercial down there recently. Only had to do one flight but a bunch of Movi work

    The throttle makes sense. I think Andy's assessment of MOSFET makes sense as well, You run a cover ya? Also no board damage?
     
  8. Steve Maller

    Steve Maller UAV Grief Counselor

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    MOSFETs were acting up earlier in the day (one motor wouldn't start) but after drying them off with my blower for a bit, they were fine. Or so I thought. I don't see a dramatic drop in current draw on any of the motors that might indicate enough to make the copter pitch the way it did, but I suppose that's possible. And BL #7 is always lower, as it needs to be recalibrated as per Holger and I have been too lazy.

    I don't use a cover. But that's in the rebuild budget. :confused:
     
  9. Steve Maller

    Steve Maller UAV Grief Counselor

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    Here are some photos of the wreckage. Like I said above, my initial appraisal of the damage is 2 CF booms destroyed, probably all the props destroyed, the GR24 radio disembowled (recovered, but deceased), the 1.3g antenna turned into art, and my MōVI battery MIA and presumed killed. I looked hard for the battery, as I didn't want to leave a LiPo behind, but I couldn't find it. Those little M5 batteries are tough to find!

    Interestingly enough, both 10000 mAh batteries stayed put, and the copter was actually still powered up when I reached it (although I'd turned off the motors). And its incessant beeping is what led me to it. That's why the GPX file actually recorded the crash (unlike more catastrophic incidents that have caused damage to the Navi board and/or power was lost on impact...or before). All indications are that the MK stack is still intact. I am also concerned about the motors, although they're all spinning freely and there are no weird noises. But I will test this as I go about re-building. First things first.

    I am sharing these photos here on this site for educational purposes. Do me the respect of not re-sharing these elsewhere.

    2014-10-20_13-19-37.jpg 2014-10-20_13-17-33.jpg 2014-10-20_13-15-51.jpg 2014-10-20_13-15-22.jpg 2014-10-20_13-14-31.jpg 2014-10-20_13-14-02.jpg 2014-10-20_13-13-32.jpg
     
  10. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Am I right that the props have a white foam core-like material in their center, Steve?

    Andy.
     
  11. Tristan Twisselman

    Tristan Twisselman Active Member

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  12. Ryan McMaster

    Ryan McMaster Active Member

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    Looks a lot better then mine did when we dropped it 75 ft. My only thought is possibly a NC issue, but that would show in the GPX.

    Side note, How you like the dual skys? Thinking about swapping them in on the Coax hex over the tiger 4012's.
     
  13. Steve Maller

    Steve Maller UAV Grief Counselor

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    It's some kind of filament stuff...kind of like packing tape. But they're definitely hollow inside...didn't know that.
     
  14. Steve Maller

    Steve Maller UAV Grief Counselor

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    You mean the motors? Those are KDE 4012-400 motors. Love em. Perfect match for the 16" Tiger CF props and my 10+kg machine.
     
  15. Holger Göhr

    Holger Göhr New Member

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    Sorry to hear about your crash Steve.

    I found a high powered led system very helpful to keep orientation. The led strips are pretty average.
    Although the LEDs are directional it is astonishing how well you can see them from below too.
    I typically work with only two colours ( red in the back and white in the front, like a car)

    You need high power LED's and a regulator, but the setup is switchable over the MK switch, so it shows you errors and low battery too...
    image.jpg

    Sorry for the bad pic, was done with the phone of the first prototype on a test copter...
     
  16. Steve Maller

    Steve Maller UAV Grief Counselor

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    The fog was pretty bad, and the lights on my copter are very bright. I think I was confused as things looked very different in the fog.
     
  17. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Do you have FPV on the aircraft, Steve? If you have the smart On Screen Display it really makes a huge difference in terms of keeping the orientation clear in one's brain....

    @Holger: Can you post links to where you can buy the LEDs and the regulator please?

    Andy
     
  18. Jose Luis Ocejo

    Jose Luis Ocejo Active Member

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    Steve could having the navi lights at the end of the booms help you with orientation instead of having them closer to the hub?
    what was your position in relation to the copter could you clearly see it or kind off due to the fog
     
  19. Steve Maller

    Steve Maller UAV Grief Counselor

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    I've been unable to get the SmartOSD to work with this machine...not sure if my board's still working.
    I'm a big fan of OSDs and FPV. My big quad with 2km+ range obviously requires that kind of data, and it's been a godsend. I wish I could get this big octo's OSD to work again, as it might have saved my bacon (vegan, of course) this time. But maybe not.
    I have a new theory about the crash, and that's that I thought my MōVI was in "airborne" mode, although it was behaving oddly. Well, it turns out today I realized it was actually in handheld mode, and it may have been the case that the DX8 momentarily lost contact, causing the copter to yaw rapidly as the MōVI tried to right itself. That might be consistent with what I saw in the air and in the logs.
     
  20. Steve Maller

    Steve Maller UAV Grief Counselor

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    In hundreds of flights previous to yesterday I've had those lights work great for me, but this crash was the first time I'd experienced what happens when I have limited visibility. Truth be told, I think my vision isn't sharp enough to distinguish the orientation of my lights when the fog is that thick.
     

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