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Dropping altitude = disaster

Discussion in 'Inspire 1 Discussion' started by BroxAg, Jun 12, 2015.

  1. BroxAg

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    So I had a bit of a disaster today.
    I got my I1 out this afternoon, got everything set up and everything checked out well, got the I1 up and went for a fly, all settings still looked good. Flew away from myself about 250m at a height of about 2m and was looking around with the camera ( was checking out one of our canola field out behind the house) and dropped to about 1.2m so could get a closer look. Turned around and headed back towards myself (at a steady pace but not flat out) as I was looking at the camera on screen I notice the ground was getting close very fast and in a slit second before I could react the camera and gimbal clipped the gound. The I1 summer salted and came to a rest in the field about 100m from me. The camera and gimble + bracket came completely detached. 3 broken props and the worst part is a broken motor support tube (front RH).
    Made the dreaded call to DJI and was pleasently surprised to have it all sorted within 10mins so off to LA tomorrow it goes.

    So a couple of questions:

    Have any of you sent your I1 back to DJI from Canada? If so who did you use fro shipping?
    A couple of online quotes and prices seem to vary from $75 - $350ish.

    Has anyone noticed altitude drop during forward flight?
    I have noticed it before a few times and corrected it - should have known not to fly so close to the ground this time!

    Expensive mistake, but one I won't be making again!
     

    Attached Files:

  2. World Media

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    I had the exact same break on my front starboard boom and fixed it in an hour for under ten dollars .... there was no way my I1 was going back to DJI for eight weeks!
    Good luck with the repairs at DJI, hopefully they will turn your repair around quickly.

    In the same way a real helicopter dips as it transitions from hover to directional flight the Inspire is liable to do the same. basically in hover you are using 100% of the power level selected to maintain attitude. when you change the plane of the rotor disc to transition in to directional flight some of the power used to maintain altitude is transferred to direction for a short period before corrected, either by the pilot providing more power or the systems making an adjustment.

    The GPS is not used for altitude correction the Inspire uses a barometer and while flying so close to the ground you really need to be fully line of sight and not relying on systems to maintain the altitude.
     
  3. offtosleep

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    Shouldn't the bottom sonar have saved you?
     
  4. BroxAg

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    I had also contemplated fixing mine myself, I carefully cleaned the camera and gimbal and put it all back together and it tested up fine so it's really just the arm that is the issue. If I had had it 6-8 months I would probably just fix it and carry on but its only a month old so it like to keep it looking "new" a little longer yet.

    Dji were very helpful and said on the phone it would be at this stage 4 weeks and no longer than 6 which is a pain but at the same time reasonable I think.

    At the end of the day it was totally pilot error and I can't blame the machine.
    Live and learn I guess.
     
  5. WTWProductions

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    Sorry to hear about your accident. I have two Inspires and they both have a tendency to drift lower when holding position, but seem fine when on the move. Actually I reckon they drift 1-2m down before settling. I also find the altitude reading displayed on the app goes off as the flight continues. The is irrespective of wind speed. So when flying low, I am acutely aware of the need to watch and correct.

    Good luck with the repair.
     
  6. Mazz

    Mazz Moderator
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    Speak with DJI they will pay for shipping. They will not offer it but they will give it to you since, you know..... they should.

    They paid for mine and others on the forum but only to those who request it.

    Edit: When I read your post and saw " pleasantly surprised it was taken care of in 10 minutes" I figured under warranty. This is the only way they will pay for shipping.
     
    turbodronepilot likes this.
  7. Kilrah

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    No because it's only really valid at small attitude angles and speeds. When the aircraft is tilted like 30° to move "relatively" fast the sonar is looking behind i.e. is quickly out of range, and even if it wasn't and one compensated for the tilt mathematically it would not be actually measuring the right thing as it's not measuring where the aircraft is. Speed also introduces measurement errors.

    And to answer to OP, yes from experience all DJI machines tend to lose a bit of altitude when flying fast. Again it's pretty normal as with a lot of tilt you quickly get errors in the feed-forward algorithm that allows knowing how much power to add to maintain height for a given altitude, so there is more dependence on the height measurement. I.e. the controller has to actually see the altitude drift in order to compensate for it, and that's a relatively slow process. You'll typically see that if you go at a safe height and start a fast movement altitude will drop at first then stabilize and get back to where it should be, but that process will maybe take 10 seconds.
     
  8. damoncooper

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    +1. Especially important flying over water. If you screech to a halt at only a few meters above the surface from full forward throttle you could be asking for trouble.
     
  9. Luis Morales

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    when moving forward it always looses altitude, this happens with every drone out there, you should always use some throttle. when you 8/12 meters up its not that noticeable but when your close to the ground its very notable, also if your too close to the ground the ground effects will also make you loose altitude quickly.

    the more angled the quad is the more altitude it will loose specially the first few seconds.
     
    Droz23 likes this.
  10. Rhino Schmidt

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    " Ihad the exact same break on my front starboard boom and fixed it in an hour for under ten dollars .... "

    Could you elaborate on that, please ? < don't ask why I'm interested ...>
     
  11. SimonMW

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    There's a video on Youtube that seems to suggest the problem was introduced with a firmware as he said it didn't happen when flying backwards. I have yet to test it myself. However it's a good reason to be very careful when flying close to the ground, and also to use throttle to compensate. Flying a toy quad that is almost totally manual will help you to learn this.
     
  12. World Media

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    Will try to post the full details in a separate thread later today ....... been flying the repaired bird on a Red Stripe beer commercial all week so having to catch up.
     
  13. Droz23

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    I trust nothing software related when it comes to safety. GPS, ultra sonic, opti are a nice features but rely on everthing working together perfectly. One needs to know flight dynamics and be ready to flip that bitch to Atti and fly! Buy a rc flight sim and practice on a heli. It is immediately apparent what is required to fly with no automation.
     
  14. Luis Morales

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    the ultrasonic sensor could help compensate but i don't think that is used.

    no matter how much automation you have on a multi rotor forward motion will always make you loose altitude as lift power is lost when tilted no matter if gps mode or atti.i always do some throttle up when moving forward.

    its a bit weird with the inspire controller (i never flied a phantom before) as the stick is always in the middle but is very doable for sure.

    also i hope we get manual mode at some point.
     
  15. SultanGris

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    it shouldnt in GPS mode however, but there was some buggy firmware that intermittently loses gps and then it drops altitude, as it will also do in ATTI mode. If you fly both modes you will notice drastic altitude change differences between them. in gps its very minimal and in ATTI it can be very drastic especially at faster forward speeds. its not so much evident on the inspire 1 but with the phantom the gps limits the speed at 30 but if you fly ATTI it will go around 50 and if youre flying gps full speed and hit the switch to toggle between the two modes you can see its angle change significantly. Ive personally noticed very little if any difference in top speed with the inspire 1 between gps or atti mode however. seems to be around 50MPH in both modes depending on wind conditions but ive hit 82.4mph in atti mode with a strong tailwind :D
     
  16. IrishSights

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    It's got nothing to do with GPS. It is only an x/y coordinate. Height comes from the the barometer. All multirotors need extra lift when going forward including full size helicopters, part of developing greater flying skills. The faster the acceleration the more lift you need to give it. Very slow acceleration hardly needs any extra lift.
     
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  17. SultanGris

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    Well I understand what you're saying and do use upwards thrust when flying in atti mode but I don't have the issue in gps mode is all I'm saying.
     
  18. John Alan

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    Sorry to hear of you wreck... :(

    Helpful hint to all... o_O
    Don't forget... objects in the camera are closer then they appear...
    Spend a bit of time hovering 'eyeball to eyeball' with your Inspire...
    Stay safe... like 10ft apart ok... :p
    Your looking with your eyeballs.. it's 10ft away...
    It will look like 20+ft on the camera view and in the video...
    Get used to that ratio in your mind... might come in handy later... ;)
     
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  19. Pottertown

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    To the OP:
    I'm in Canada, I just got my bird back from a warranty repair. 4-6 weeks is a lie. 8-10 is more likely.

    As for shipping, Since you're on the hook for it, i'd probably just send it Puro and insure it (UPS expedited might be cheaper, but careful what option you pick as one has some on delivery shipping/customs/brokerage charges that can screw things up).

    I was also wondering about the forward flight altitude drop... Good to know i'll need to sharpen up my throttle/forward flight game.
     
  20. kenny kustom

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    Mine was 4 weeks from the day they signed for it, till the day it left them. I cant count shipping time, as shipping to canada always takes longer. They have no control over that.