Welcome to InspirePilots.com

Join the leading DJI Inspire community for free!

Traveled 600 miles to fly and didn't calibrate compass

Discussion in 'Inspire 1 Discussion' started by sanderx, Jun 28, 2015.

  1. sanderx

    Joined:
    Jun 10, 2015
    Messages:
    142
    Likes Received:
    60
    Hi, I have been reading the posts here around compass calibration and noticed people calibrating their compass before each flight and some who don't. I calibrated my compass when I got my inspire and it has been flying like a charm. This weekend I traveled to northern Maine to do some flying. I decided not to recalibrate my compass even though it was 600 miles away from where I initially calibrated my compass. Before taking off I checked the sensors and all readings were fine, all mod values in required ranges. I flew the bird in multiple locations and it was rock solid. I usually fly in attitude mode only as I like the behavior for video shooting much better but I flew in gps mode a number of times to check the behavior and it worked perfectly.

    Something to consider for folks who feel they need to recalibrate their compass before each flight. You probably don't have to if you have a good initial compass calibration done.
     
    The Editor and damoncooper like this.
  2. ajohnsonlaird

    Joined:
    Mar 4, 2014
    Messages:
    139
    Likes Received:
    56
    Actually, I think you might have been lucky -- my understanding is that the reason for calibrating the compass is that the Earth's magnetic field varies from location to location and is also influenced by your proximity to things magnetic (e.g. metal fences, buildings, rebar in concrete).

    So the general rule that I see folks following is to recal the compass whenever you fly from a different location, not before every flight from the same location.

    EDIT: And I should have added that you need to be away from anything that distorts the Earth's magnetic field before you do a calibration as you run the risk of calibrating in an erroneous reading.

    I think I'm correct in saying that the IMU mod values are directly from the I1's accelerometers and, if that's correct, then they are not influenced by the Earth's magnetic field. They would be influenced by the Earth's gravitational field, which does vary in intensity from place to place (depending on how close you are to the center of the Earth).

    As far as I can tell, if you have the I1 level and you recal the IMU, you only need to do that once per version of firmware -- that is, each time you update the firmware, it would be prudent to recal the IMU

    Hope that helps.
     
    #2 ajohnsonlaird, Jun 28, 2015
    Last edited: Jun 28, 2015
  3. Luis Morales

    Joined:
    Apr 15, 2015
    Messages:
    270
    Likes Received:
    120
    Location:
    Madrid
    its recommended, not mandatory, i have done it too, 400/500km no problem.

    it is recommended because of the magnetic declination, if you want the correct one you should recalibrate.
     
  4. The Editor

    The Editor Moderator
    Staff Member

    Joined:
    Aug 7, 2013
    Messages:
    6,701
    Likes Received:
    3,860
    Exactly my point as I have mentioned numerous times on this forum.
    You do not need to recalibrate your compass every time you change your pants or your mind :pand by doing so you run the risk of introducing an error.
    Thank you for posting this.
     
  5. DreamMN

    Joined:
    May 9, 2015
    Messages:
    18
    Likes Received:
    3
    Location:
    Duluth, MN
    I have been religiously re-calibrating my GPS before each flight, except for 1 time... I will never forget or forgo a flight without doing this again. This might be a fluke incident or me not fully understanding how the ground sensors work.

    List of Questions:

    1) Is there a level of flight that the craft must be at before the ground censers cease to function?

    2) Has anyone had any issues with flying in state parks? I know Federal lands, parks have no fly zones, but have anyone had any issues with state parks? You hate to ask for fear to get a "NO". Sometimes it's better to get a warning for not knowing if caught, than to ask and get a "NO" just because the state official doesn't know, and says no anyway.


    My goal was to take pictures on a raging river at a state park. I was thinking of signal range and took off from a cliff about 20ft high. I did an auto lift off, it hovered 3.5ft, and retracted the landing gear. I then went over the cliff, IT DROPPED LIKE A ROCK along with my heart... Then it took off to the right and crashed into high grass and a tree... It took me 20 min to find it. Using the GPS guide I found craft. I had quickly full throttled to see if I could regain lift, it didn't seem to help...

    3) Has anyone had issues with this? Taking off from a cliff area?

    The only thing I can think of is that the craft registered that it lost the ground and needed to regain its altitude. Before I try that again, I was going to test it by taking a small sheet of plywood putting it on the ladder. Taking off from a ladder, after it's up 3.5 ft then move over 5 ft see if it falls... There must be a height that you must be at for the the ground sensor to disengage. Maybe 10ft? I don't know. Then fly over a cliff. Or is it not smart enough to stay at a GPS location. I did hover at 7 ft, then put my had under the sensor, it did raise a little... IDK Any thoughts/
     
  6. The Editor

    The Editor Moderator
    Staff Member

    Joined:
    Aug 7, 2013
    Messages:
    6,701
    Likes Received:
    3,860
    Page 16 and 17 of the manual !