Comment by energywut

Comment by energywut 6 days ago

35 replies

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I have ~200 acres of land I fly a drone survey mission to map. Today, that piloting is done by dronelink and a DJI drone. The challenge is that it's about 3 hours of flight time, give or take, to cover the space, and a given battery is good for about 35 minutes of flight time.

I have 4 batteries, which means I basically need to be refilling my batteries as quickly as I consume them in order to keep flying continuously (unfortunately, even with a quad-charger, I cannot fully sustain this.)

I would LOVE to have a fixed wing drone that could fly over the area and snap close-to-nadir photos as it did so, but the complexity of building and programming a hand built drone seems so much higher than deploying an off the shelf DJI drone. Additionally, the land is steep, with a 1,000+ foot elevation difference, and rugged, and the neighboring land is airspace I cannot fly within, so I couldn't use it to perform my turns.

Author, or others, any thoughts on whether it's worth pursuing a fixed wing aircraft to perform this mapping mission? Or is the best bang for my buck to just buy enough batteries to fly the mission continuously on an off the shelf quadcopter?

tsungxu 6 days ago

Great question! I don't think there's any sub $5k VTOL you can just buy COTS that can get close to 3 hours of range. Also, nothing is as plug and play as DJI. If you're motivated enough to do a little DIY and learn how to use Ardupilot or PX4 (easier), you can buy a kit like the Heewing T2 VTOL and assemble yourself. But I don't think that will do more than two hours flight time, even with a similarly high energy density battery pack to what I used.

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bagels 6 days ago

Instead of one drone, buy 10, and send them out in parallel, and charge them all simultaneously.

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  • energywut 5 days ago

    The FAA does not permit this, by default. You are allowed to remote pilot in command one drone at a time. I could apply for an FAA waiver (I have one to fly beyond VLOS). I've genuinely considered doing so, but I don't know how I could convince the FAA that I could safely monitor multiple drones simultaneously.

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  • psadri 6 days ago

    Horizontal scaling. I love this out of the box thinking.

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abrbhat 6 days ago

200 acres should not take 4 hours. It should be coverable within 20-25 minutes with 75-65 overlap, flying height 120m with something like Mavic 3 getting a GSD of 3.5cm/px. Look at optimizing your flight overlaps and height.

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  • lazide 6 days ago

    It depends a lot on the terrain type - highly repetitive terrain requires higher overlap. It does sound like they have some broken setting somewhere though.

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    • energywut 5 days ago

      It's heavily pine forested mountain areas. With a 65-75% overlap, the SFM algorithms struggle to produce sufficient details. Additionally, because of the verticality of the terrain and very tall pine trees there's a need to have multiple angles to generate a good orthophoto. So the grid is denser than other environments for a reason. I'm continuously updating my flight plan based on the results generated -- squeezing density up/down based on observed results.

      The 4 hours is an overestimate, it's probably genuinely closer to 3 hours flight time.

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      • lazide 5 days ago

        I have a similar situation with a smaller plot of timberland. Sometimes even with 90% overlap it can’t stitch. I get your pain.

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      • noveltyaccount 5 days ago

        Just curious, why do you have to survey repeatedly? Are you monitoring something changing?

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        • energywut 4 days ago

          The area was partially clearcut about a decade back. Some areas are due for brush management and some for commercial thinning. Additionally, because it is alpine and contains a stream used by fish for spawning, it is interesting to see the variations in snow load and water flow in the stream year over year.

          So there's at least a reason to get out each winter (snow load), spring (melt/brush growth/flowers), and summer/fall (stream health/identify trees once brush loses leaves).

          I also like seeing if there's trees in stands dying at an unusual rate, which might indicate pine beetle infestations or sickness that I'd need to take care of.

          Also, it's a fun hobby and a cool dataset to flip through.

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cyanydeez 6 days ago

I reviewed and purchased a smaller drone, from WHISPR. Through that, I looked at similar VTOL drones, which OP is demonstrating. In theory, they're cheap:

https://www.uavmodel.com/products/makeflyeasy-hero-2180mm-ua...

This one has a maximum climb rate of 3 degrees. Which means you'd need to plan a route that's continously climbing, and tacking back and forth to avoid going steeply. So you would probably combine flight planning using Mission Planning: https://ardupilot.org/planner/ and custom json tweaking following MavLink protocol: https://ardupilot.org/dev/docs/mavlink-routing-in-ardupilot....

The open source flight controllers and systems are https://ardupilot.org/copter/docs/common-autopilots.html#ope... a good place to start. There's a few orgs building the full experience, but you'll of course pay for fully integrated, but still open source, hardware+software.

The scenario you describe is exactly what a VTOL or normal play is for; quad copters simply do not cover enough ground.

Also consider the camera. DJI typically ship with really low quality cameras, but https://www.bhphotovideo.com/c/product/1785754-REG/sony_ilx_... would get you a much higher pixel density so if you're more interested in the imaging, you can flight higher, near the licensed ceiling, completing more ground faster.

I've also found AI models know how to calculate pixel densities, so it's pretty easy to mock out a flight plan even if you dont have the actual drone available.

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  • LargoLasskhyfv 6 days ago

    While that Sony piece of kit probably can do some cool things, 2950$ without objective/lens, seems rather expensive. Also 8.6 oz / 243 g (Body Only) don't look that light to me.

    I'd probably go for some Sony Experia 10III[¹] or upwards, for no more than 300$ at 170 g (unmodified), and strip the hell out of it. Does it need a display, all the parts of the case, and so on? Can can I use its GPS, and pipe it into the flight controller, instead of having to rely on something more powerful and heavy, power guzzling?

    [¹] because https://xdaforums.com/f/sony-xperia-10-iii.12225/

    cf. https://en.wikipedia.org/wiki/Ingenuity_(helicopter)

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    • cyanydeez 6 days ago

      If you use ground control points, GPS accuracy isnt a bog deal, but im willing to bet the standard GPS puck still gets better.

      I dont know much about the weights involved, but hardware surgery was not interesting to me.

      Keepbin mind tge guys starting at DJI and youre proposing stripping dowm a camera

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  • cyanydeez 6 days ago

    for processing, I setup opendronemap: https://www.opendronemap.org/

    There really is a full open source hardware/software path, which is heartening.

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    • tsungxu 6 days ago

      This actually has decent flight time! Could probably push close to 3 hours if using higher energy density (and cost) battery cells like the silicon anode ones I used.

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froj 6 days ago

I think this fixed wing drone https://ageagle.com/drones/ebee-x/ would fit your usecase.

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  • arijun 6 days ago

    How much is it? The pricing section is blank for me

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yard2010 6 days ago

If you want and have time you can enter the world of FPV, building a drone yourself. You can change the frame, motors, ESCs, controllers etc. You have much more control compared to what you have with a DJI. It's very rewarding, too. But it takes time so it might not be the economic option.

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Daviey 6 days ago

It would be a project, but the HeeWing's T2 Cruza VTOL is extremely interesting as you could put in both a high capacity battery and a good quality camera.

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Baeocystin 6 days ago

For now, the answer is just buy more batteries and use a DJI drone. There is nothing else that comes anywhere close in terms of bang for your buck.

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aa-jv 6 days ago

The OP VTOL drone is aesthetically pleasing, I feel, but is over-engineered for a task such as mapping long distances.

For your needs, a slow-stick with a KFM wing would suffice - the smallest, lightest, simplest, most capable airframe one can build, and that is a slow-stick[0] with KFM wings[1].

VTOL is cool for those of us raised on a healthy sci-fi diet, but is entirely unnecessary for a slow-stick, which can be hand-launched directly into the air (vertically) and landed at a stall within a meter.

Plus, it is small, light, effective and extremely simple, which means its a lot easier to repair and maintain. Add some ardupilot magic and you've got a really capable platform for surveys and reconnaissance.

tl;dr Consider building a small fleet of slow-stick+KFM planes, attach your camera to it, and do your survey that way ..

[0] - https://www.rcgroups.com/forums/showthread.php?1395335-Begin...

[1] - https://www.flitetest.com/articles/kfm-wings-a-basic-explana...

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  • tsungxu 5 days ago

    Aesthetics follows function in this case. And agreed VTOL is not beneficial at hobbyist scale for most because of the ease and short distances required to hand/runway launch and land an RC plane

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    • aa-jv 5 days ago

      >Aesthetics follows function in this case.

      Not sure I agree with you here. The very same functionality can be attained with far less plastic.

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yapyap 6 days ago

How often do you need to do this mapping? if it’s every day it would definitely be worth it to look for another solution, if it’s every 6 months or so this seems tedious but doable.

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debbiedowner 5 days ago

Better camera on the drone to fly faster and higher.

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  • energywut 5 days ago

    I am limited in height I can fly by the FAA (400 feet AGL).

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    • debbiedowner 5 days ago

      Assuming 200 acres is 0.57x0.57 miles. If you fly at 15 mph you can do 15 lines in 30 mins. The lines would be 200 feet apart, and you'd move 22 feet per second. 15MP images would be 10 pixels per foot and motion blur with 240fps would be 1.1 inches.

      Anything wrong with that?

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      • energywut 4 days ago

        0.57 x 0.57 miles is a good estimate. The lot is more or less square.

        Yes. Maintaining 15mph is tough because of elevation changes. The land has a 1,200 foot tall ridge in it, so the drone must gain (and lose) 1,200 feet across that 0.57mi span. Which is steeper than the drone can do while maintaining a forward speed of 15 mph.

        Additionally, SFM algorithms struggle with repetitive environments like pine forests, where there are not clear points or lines they can align. GPS data helps somewhat, but if the pictures are too sparse then it can get confused and start stitching images together incorrectly. Additionally, too few images lowers the fidelity of the output and causes strange gaps and black spots in clearings (where the clearing is visible in one pass but obscured in another.)

        Finally, radio transmissions require two flights due to that ridge. I need to fly once on either side or I lose signal. There is no accessible point on the property I can maintain visual line of sight across the entire span, and "mountain" is a pretty good radio signal attenuator.

        I'd LOVE to have some automation help in developing a flight plan, as right now it's manual, and I'm creating little segments myself, individually placing points and grids. Several tools claim to support automatic elevation, but none of them do so well when you have a 1000+ foot cliff or a narrow stream bed that has cut 20 feet into the earth in your environment.

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