Over the past several weeks I have been corresponding with Dorn Cox of farmhack.net about the uses of fixed-wing unmanned aerial vehicles (UAV), more commonly known as drones, for farm monitoring applications. Most people who follow this topic immediately think of quadcopters when they think of small remotely controlled UAV’s, but fixed-wing models have a number of features that are advantageous.
First, the most immediate benefit is the flight time when compared with quad or hex copter models. A quad is likely to get between 15 and 20 minutes of flight time on a single charge. Naturally, running all those motors at high speeds drains battery charge quite quickly. A fixed wing craft like the 3DR Aero has a flight time of 40 minutes on a single charge; one can cover signiciant territory in 40 minutes.
Currently fixed-wing craft can fly a path of GPS waypoints with much better precision and efficiency than a quad; this may change as flight controller hardware and software improve, which is happening quite quickly. Below is a sample image, which is quite comparable to the aerial imagery most remote sensing professionals get from more traditional aerial photography.
3D Robotics is now offering the 3DR Aero for a fairly reasonable price, though certainly you would have to put this rig to work to get a good return on investment. You might be thinking what I was thinking when I first saw this rig: a styrofoam frame! That will get wrecked in five minutes. But Dorn assures me that this stuff is pretty sturdy: “The EPO foam is tough stuff, can be repaired and is like flying your electronics in a shipping package- the sky walker airframe they use is less than $200 and some of them are less than $100. Cost is all in components”.
Before you go out and buy yourself one of these rigs, don’t fool yourself into thinking that this process is easy. According to Dorn, there are three areas that will require a signficant time investment and learning curve: the navigation software, the image processing software, and most importantly, learning how to fly. Fortunately for fixed-wing craft, there are some pretty good flight simulator software packages out there. Here’s a pretty good forum post that compares RC flight simulator software.
And remember, this technology is still in development, rapid development to be sure, but development nonetheless. There will be factors that you may not have thought of, like the nose shifting up slightly during stable flight, which affects image quality, or the hours required to get navigation software and camera to communicate, or the fact that you have to learn how to use CHDK (Cannon Hack Development Kit) if you want to have any chance of making this work. And of course, getting the images is only the beginning, then you have to process them and get good quality data. Samplepoint software is a good option for getting some usable data in consolidated fashion, though most aerial Samplepoint applications I’ve seen are still fairly experimental. The good news, again, is that development is happening at breakneck speeds. If you’re adventurous and technically-minded, you might want to dive right in. If not, you may want to check back in six months to a year and see if the technology has matured enough to make it completely plug and play.