Lost A Lightweight Quadcopter? Here Are The Best Ways To Find It

Lost aircraft are harder to find when they are physically small to begin with. Not only are they harder to see, but the smaller units lack features like GPS tracking; it’s not normally possible to add it to a tiny aircraft that can’t handle much more than its own weight in the first place. As a result, little lost quads tend to be trickier to recover in general.

Fluorescent tape adds negligible weight, and will glow brightly at night under a UV light.

The good news is that [Eric Brasseur] has shared some concise tips on how to more easily locate and recover lost aircraft, especially lightweight ones. Recovering aircraft is something every aircraft hobbyist has had to deal with in one way or another, but [Eric] really has gathered an impressive list of tricks and techniques, and some of them go into some really useful additional detail. It occurs to us that a lot of these tips could apply equally well to outdoor robots, or rovers.

Even simple techniques can be refined. For example, using bright colors on an aircraft is an obvious way to increase visibility, but some colors are better choices than others. Bright orange, white, and red are good choices because they are easily detected by the human eye while still being uncommon in nature. Violet, blue, and even cyan on the other hand may seem to be good choices when viewed indoors on a workbench, but if the quad is stuck in dark bushes, those colors will no longer stand out. Another good tip is to consider also adding a few patches of fluorescent tape to the aircraft. If all else fails, return at night with a UV lamp; those patches will glow brightly, and be easily seen from tens of meters.

Some of the tips are used while the device still has power, while others don’t depend on batteries holding out. [Eric] does a great job of summing up those and many more, so take a look. They might come in handy when test flying quadcopters that are little more than an 18650 cell, motors, and a 3D-printable frame.

24 thoughts on “Lost A Lightweight Quadcopter? Here Are The Best Ways To Find It

    1. I think this set of tips was aimed at, and I quote, “tiny aircraft that can’t handle much more than its own weight in the first place”. Adding extra electronics would add bulk, weight, and decrease flying time.
      (Yes, I do understand that BLE doesn’t use a lot of power, but sometimes every milliamp-hour counts.)

  1. There’s a device that used to turn up in the model aircraft press (Generally, not specifically MAP, though in later life that was Model and Allied Publications) for finding the bearing of a flyaway model aircraft. A version would show up as plans or kit every 5 to 10 years. It consisted of an indicator wire suspended over a mirror, which could be angled and rotated. This was set on a bearing card, which one would align with north, so your bearing meant something, but if you did this in a panic, you could measure degrees off north afterward. This would be mounted to a tripod, or other firm stand. In use, you would look at the reflection of the aircraft in the mirror, and align the mirror such that it appeared to be flying along the indicator wire, this would give you the bearing of the aircraft.

    If you have an accurate bearing in which it was last seen proceeding, you can target your search into a wedge delineated by a degree or two of that, and extending to the maximum possible flight time.

    In theory, using the same techniques of compass sensor, camera, location, acceleration and attitude sensors in a modern cellphone, that stargazer and planetarium apps use. One should be able, to take two “align it with the crosshairs” shots and have the phone calculate the bearing. Also should be able to get it to draw you the search area on a map. Possibly one could do it with video too, but might be expecting a bit much to real time track the object in the camera frame and relate it to all sensor data, without lagging and becoming wildly inaccurate, when one is doing this in a higher level language a few abstractions above the hardware.

    Don’t forget the obvious though, help your model aircraft return to you, by sticking your name, email, phone number, address etc on it. Possibly you could split a War Amps key tag to reduce the bulk and glue that on somewhere.

    1. If your compass has a sighting mirror, fold it open flat, rotate flat to line up the mirror’s index line with the observed flight path, rotate the compass wheel to align magnetic needle with North, read your bearing.

      PITA with the ‘pilot survival compass’ Silva Type 25 Prospector with the hanging starlight ‘mirror’ (polished metal) that folds out under the tiny compass housing. Noisy little ‘mirror’ too, for something that’s supposed to be SERE. OMG apparently those are old & rare now.

  2. What about adding a key chain finder? ;)
    Seriously, though, a little beeper or radio beacon may do.
    The latter can be found by directional finding.
    Just like on a fox hunt (aka foxoring).
    If you choose the 80m band and are licensed, a little quarz oscillator is all it needs. If memory serves, you’ll get away with a little beep-beep-beep tone instead of a full morse ID for testing purposes (training foxes used that). A simple beep tone generator can be build with a blinking lamp or blinking LED.+transistor. :)

    1. I added the key chain finder idea to the article. It’s perfectly sound. A manufacturer should actually provide such a device adapted for tiny quadcopters and other lightweight flying devices.

  3. For larger drones and fixed wing I really like the idea of the tBeacon. It uses a small 433Mhz radio and a GPS module and transmits its coordinates by voice when you send a call tone. You can diy one with a super cheap OrangeRx 433 receiver.

  4. Retroreflective tape is even better than fluorescent. Even a small visible-light penlight held next to your eyes will produce a bright reflection at even a significant distance if it’s not obscured.

      1. If you google something like “How to apply reflective glass beads” you’ll find descriptions of sprinkling the beads onto wet paint etc for artistic or projection screen purposes.

      2. I know what you mean; I found a piece at a surplus store years ago and grabbed it because I didn’t know if I’d ever find any again. At least now we’re spoiled for choice, and I think pretty much anything that’s marked as explicitly “retroreflective” will do a decent job.

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