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Strange question, 3 tips and a fat man's squeeze (not in that order)

Discussion in 'Inspire 1 Discussion' started by Eye in the sky, Jun 4, 2015.

  1. Eye in the sky

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    Hi all,

    I was in Chattanooga the other day, and wanted to fly my inspire from the top of Rock City on lookout mountain on the border of Tennessee and Georgia. Supposedly you can see 7 States from the top of the mountain. A drone being able to film 7 states in under 3 minutes? May be a first, if you ask me.
    And for those who are going to get all hot-and-heavy about about rules and regulations, :) I asked for permission beforehand, and was told "sure, just don't bother anyone else".
    So, the trek begins.
    I carried the inspire in it's case, my 2 canon 7d's, big lenses and all my other necessary camera gear (or so I thought) on the round trip.
    There's an area called "fat mans squeeze", which is basically a very narrow space between 2 huge rocks (or 1 extremely huge rock with a cleft in it) that runs around 30' high and 45' long, and is around 20" wide at it's narrowest. I'm not too big (okay, about 20lb's overweight), but with all the gear I was carrying, I got just a little stuck in the space. I managed to extricate myself after jostling backwards and forwards for a little while.
    So tip 1: Know what you're getting into (literally) before you take that step.

    I then hiked to the top of the mountain, expecting to fly my inspire from the top of a pristine, natural, building-free zone on the mountain 1/2 hour before sunset.
    I got there and it was more commercialized than Disney World (okay, so I'm exaggerating a little. But really, only a little), not the scenic location I was planning on shooting at all.

    So, tip 2: Please see tip number 1 above: Know what you're getting into (literally) before you take that step.
    In other words do your research beforehand.

    At this stage, I'm on top of the mountain, with a huge drop-off in front of me (no clue how far down, but it was definitely waaaay more than my comfort level due to my ignorance). and I suddenly realize that I have no clue how the inspire measures altitude. From the ground under the inspire? Or from the home base?
    At this point, I have no clue if the inspire is going to go over the cliff edge, and then drop below the height limit I've set (which is 400' and I really had no clue how far down the cliff went), and then won't come back up to me because I'm above the height limit, or, if it's all in my head and there won't be a problem.

    So, tip 3: Please see tip number 1 and 2 above: Know what you're getting into (literally) before you take that step.

    In other words do your research beforehand. On the location and the capabilities of your machine.

    At the end of all of this (actually, in the middle, as I still had to walk all the way back), I decided not to fly at all, as I really wasn't prepared to lose my drone.

    Long story short. I got fitter carrying everything and not using it, and now I'm hoping to strengthen my gray matter, by finding out how the inspire measures altitude.

    Anyone have a clue?
     
    TrumperyDust likes this.
  2. TrumperyDust

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    Great question! I was wondering how my quad would measure its height whilst filming a wind turbine farm on top of a small mountain just yesterday. I knew my bird wasn't in danger but I was curious as to how it might adjust its ceiling height to the earth as the ground drops away. I'm pretty sure these copters have barometers in them but can't altitude also be measured by GPS.??? Not sure how that works. Just don't know. I'm sure one or two of these guys knows how the drone will react. I think in your situation it was smart to walk away so you can fly another day.
     
    #2 TrumperyDust, Jun 5, 2015
    Last edited: Jun 5, 2015
    Eye in the sky likes this.
  3. The Editor

    The Editor Moderator
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    Don't worry, your Inspire would not have suddenly dropped into the abyss below. The aircraft has no clue its hovering over certain death it doesn't care.
    Its height is measured relative to its take off point not above sea level.
    So whereever it takes off from that will be zero as far as the I1 is concerned, then it can either go negative (below take off point) or positive (above take off point). If you had lifted off on the edge of the drop off and hovered at 10ft then moved out to be directly over the drop it would still have said it was 10ft as it is all relative to its start point.
    The I1 uses a small solid state barometer to measure change in pressure (and thus height) to a resolution of around 10cm.
    GPS is woefully inaccurate for altitude measurement and errors of +/- 400ft are not uncommon so thankfully the I1 doesn't rely on GPS for its height data.
     
  4. ajohnsonlaird

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    GPS might give you height above mean sea level (AMSL), but it cannot give you height above ground level (AGL) without a terrain map. The sonar sensors in the I1 might give you height for the first ten feet AGL, but not much beyond. Therefore, my money's a pressure transducer that simply take a reading at the take-off point and calculates everything relative to that (to height above home -- no idea if there's an approved abbreviation other in the UK where it would be called QFE (field elevation)) -- so it's not even AGL as the ground over which the I1 is flying is likely not at the same height AMSL as the take-off point.

    Andy.

    EDIT: The Editor beat me to it!
     
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  5. Eye in the sky

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    Thanks for the reply trumperydust.
    I agree, If in doubt, don't fly.
     
  6. Eye in the sky

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    Thanks so much.
    I feel a whole lot better now. Unfortunately, I'm also 900 miles away, and not sure I'll get back there any time soon :).
    But at least now I know, and don't need to worry for the next time.
    Better safe than splat.
     
  7. Eye in the sky

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    Thanks Andy.
    I appreciate the reply, even though the editor beat you to it. You still took the time out to read and reply.
     
  8. damoncooper

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    Thread notable quotables:

    "The aircraft has no clue its hovering over certain death. It doesn't care."

    "Better safe than splat."


    ImageUploadedByTapatalk1433505424.337878.jpg
     
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