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Topic starter
23/09/2025 10:27 pm
Hello everyone, my name is Devan, and I would like to open a discussion about finding a lost MagArrow.
To give you some background, I lost my MagArrow II while it was mounted below the DJI M400 during a flight mission in a highly dense forest. We have the drone flight log, which indicates that it was stuck in a tree within a 50 m radius of the last known location. We have searched the whole area, but due to a highly dense forest and steep terrain, it was very difficult to find the MagArrow II and the drone on foot.
For more than a month, I presume it was still perched within the tree canopy. And now we have bought a new MagArrow II to continue our survey. In this case, I desperately want to find and retrieve the lost MagArrow using the new device.
I have an idea that if I conduct a 5 m spacing grid in both East-West and North-South directions within a 100-meter radius of the last known location, we could eventually narrow down our perimeter by finding an anomaly that indicates the lost device. Therefore, I have a few questions:
1. How magnetic is the drone and the MagArrow II?
2. Is it feasible to find the old MagArrow with the new MagArrow with the stated method? Alternatively, do you have any effective suggestions for a different approach?
I appreciate any insights you can provide. Thank you!
23/09/2025 11:14 pm
Hi Muhamma
Unofficially, the MagArrow was designed to be very non-magnetic, so hard*
*But your drone, with its big motors and the magnets in it are much more magnetic
But I would suggest flying higher (due to the last drone hitting something) and with a quality mounted camera, looking down at 45 degrees, record raw (for clarity) video footage, and review it. Ideally, following the same survey lines and flight direction. If nothing is visible, try a different height and angle to gain a different view through the foliage. Ideally, with the sun at an angle from behind you to assist in lighting up the view.
That's my suggestion based on what you have described. Wishing you the very best "luck"
Muhammad Devandra and Rui Zhang reacted
24/09/2025 8:43 am
I agree with Peter that it will be very challenging to locate the MagArrow II or the drone using the magnetic method. You will need to get to <0.2m from the MagArrow II to detect any significant magnetic signature. As for the drone, the detection range is probably < 1 m because the 3 m suspension cable is far enough to make the drone "invisible" to the MagArrow. As Peter pointed out, vision method probably works better than the magnetic method in this case.
Wish you the best luck!
Topic starter
24/09/2025 7:57 pm
@rzhang @georesults thank you for your responses!! I also believe visual investigation through a high-quality camera mounted on a drone would also become an alternative approach.
Regarding Rui's answer, when you mentioned <0.2 m and <1 m, are we discussing height differences between a new device and the old one, or is it about the investigation flight spacing?
I appreciate your responses and I'm looking forward to your feedback. Thank you for your wishes and have a great day!!
-Devan
25/09/2025 8:16 am
@muhdevandra The height difference between your target of interest and the magnetometer is related to the investigation flight line spacing. As a general rule of thumb, the line spacing should be < 2 x height. What is important is the distance between your target of interest and the magnetometer. It doesn't matter whether the distance is off vertically or horizontally.
Muhammad Devandra reacted
