There is a heated discussion below about quadcopter vs. fixed wings for agricultural applications and I mentioned I would write up how Agribotix selected the RV Jet as an airframe.
Briefly, a fixed wing is roughly five times more efficient than a quadcopter for a given weight and configuration (approximated by the glide ratio and validated through our experimentation). Since farmers typically work in quarter and half sections throughout the Midwest, this means the airframe should be capable of surveying 320 acres, which is practically possible only with a fixed wing.
However, all fixed wings are not equal. A flying wing is much more durable than a traditional airframe, in addition to packing smaller and being easier to set up and tear down. We experimented with a number of different flying wings, but found the best overall characteristics to lie with the RV Jet. If you're interested in more details, take a look at our blog post over at http://agribotix.com/blog/2014/5/26/the-agribotix-journey-towards-selecting-an-airframe
Replies
Hello Daniel,
I am wondering, what is the set up of your RV Jet (motor, props, ESC, battery, flight controller, fpv and ground station)?
I am new for this kind of UAV platform. I usually work on satellite remote sensing application on agriculture. I want to built the same UAV platform as you did.
Thank you
Hi Eko,
We've experimented with a number of different servos, props, motors, etc. and are still nailing down a final configuration. It would take me a minute to track down the most recent build, but I can post it here in the next week or so. What has been consistent is we really like the PixHawk and don't use FPV (all autopilot).
If I don't post something here by next week, shoot me a message and I will put together that list for you. BEst of luck with your project!
Dan
Hoi Daniel,
I am still here waiting your RV Jet configuration :D
Hi Eko,
Thanks for the reminder. Good luck and let me know if you have any questions.
The plane is composed of the following parts:
Event 38 Red notch filter
We use the following for the ground station:
DIYD member Rory Paul made some interesting observations about precision agriculture and the choice of platform at our show recently
Thanks for the link. Tom McKinnon, also on the Agribotix team, was at sUSB Expo and saw that talk.
Rory makes a lot of good points, but we actually haven't met a single grower or agronomist concerned with or even interested in inch-scale accuracy. We initially thought we would need accurate ground control points, but have found that farmers know their fields and our imagery is, in general, allowing them to pick up fairly gross level issues. Additionally, rural internet connections tend to be pretty slow so we have actually been reducing resolution to decrease transfer times.
Thanks !...did you try out the Zephyr II ?
We did try the Zephyr, although it was weighted down with a Kevlar jacket we thought would be necessary after our issues with the Penguin's durability, so a fair head-to-head comparison was not made. That said, with the extra weight the Zephyr did not take off well. Part of the problem was the weight, but Zephyr wings are also substantially shorter than those of the long wing RV Jet, so it may be more difficult to take off and land.
Thanks for this...and timely, since I'm looking at my next mapping airframe, and was narrowing between the Penguin and the RVJet!
Do you find the RVJet flies slow enough to get good mapping coverage in more diverse landscapes?
Glad we were able to write a timely article!
The stall speed on the RV Jet as we have it configured is around 8 m/s. We typically fly at 14 m/s to be able to cover a quarter section in about 20 min. Given our resolution of about 1 in/pixel, this translates into about half a pixel shift per image at 1/1000 s shutter speed. We have not produced clearer images by flying more slowly at 100 m, but you would need to fly more slowly if you were interested in flying at lower altitudes. Please let me know if I can answer any more questions and good luck with your farm!
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