Electric Aviation With Unlimited Range Is Getting Cheaper & Smaller
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For the most part, we treat electric aviation like it’s something that we’ll see in the future. I mean, batteries are expensive and heavy, and they don’t hold that much energy per unit of weight. So, compared to, say, kerosene (jet fuel), batteries take up a lot more space and weight capacity in a plane design. This means either really poor range or carrying around nothing but batteries (which isn’t very useful).
But that’s only true for the largest of planes. The smaller the plane, the easier it has been for companies to electrify or even go full electric with it it. Once you get down to unmanned planes and helicopters that carry something like a small sensor payload (cameras, etc.), you’re in a realm where all-electric aviation has been around for over a decade.
Though, small unmanned systems like quadcopters tend to only fly for 30–45 minutes at most, while small fixed-wing remote piloted airplanes tend to fly for maybe 1–2 hours. What if you want to fly for a number of hours or even days to cover more ground? It turns out that there are some answers, and the usually involve solar.
Large, well-funded entities like NASA have experimented with solar aircraft in the past that can fly indefinitely, but the technology is starting to reach low enough costs where DIY experimenters can have a go at it.
In this video, ProjectAir’s team started with some bench testing. The big question: would solar and a modest battery storage system be able to keep a motor going and thus keep a fixed-wing drone in the air? The answer appeared to be “yes,” but as long as efficient solar cells (20%) were used.
The first plane, built with foam board and 24 of these solar cells, was very simple. The first version, with no solar, wasn’t a great design, as it had too much drag. Adding cells required using hot glue to give the cells extra strength. Once it was set up to fly, it was only using a battery for radio controls. Sadly, this first design didn’t get very high off the ground in cloudy weather. The second flight was better in bright sun, but eventually lost power on some turns, causing it to quickly lose altitude. A temporary loss of sun due to a passing cloud took it out of the sky, damaging the frame and the cells.
At this point, the plan was to build a larger, more efficient airframe with more solar and some battery to prevent power loss during banking, passing clouds, and more. This approach worked well on the bench, so they added the cells to a flying wing plane design that could fit 60 solar cells! Sadly, the plane didn’t initially glide well, but moving the battery forward led to better gravity and then better gliding.
Rather than move on with the large plane, they decided to experiment with the autonomous flight systems with a smaller battery-powered plane. After some trial and error (the autopilot kept diving the plane right into the plant life), and some help from an expert, the team managed to figure out that the electric motor was interfering with the GPS receiver, confusing the software and causing the crashes. To alleviate this, they relocated the receiver and magnetometer/compass, making everything work properly.
With the software and flight hardware running, the team worked on putting all of that into the solar-battery plane. Facing a bad forecast, the team rushed to get the plane ready for a test flight to avoid having to wait two weeks. After cramming nine hours of work in on one day, they got it ready for a test flight, but they were very nervous about the flight, flubbing the first attempt at a launch. But, on the second try, it was airborne and working in autopilot as the clouds rolled in.
But, despite the clouds, they were able to determine that the solar cells were making the battery deplete at a lower rate than it did on the bench with no help from solar, so it was definitely helping. But, after what appeared to be a successful test flight, the motor started losing power and the team lost control of the plane.
Toward the end of the video, the plane took a nosedive, and landed in an empty field with a sickening SNAP!
After investigating the wreckage, the team was able to figure out that the plane had suffered a complete power failure. Why? Because the solar charge controller overcharged the cells, pushing the motor to over 13.2 volts. This didn’t happen on the bench, and wouldn’t have been a major problem, but the team forgot to wire in the backup battery that was supposed to run the avionics systems. This caused a full loss of control, preventing an emergency landing.
The team plans to build a second plane soon, and get all of the overcharging issues worked out with the solar charging system. The next plane will need some new panels and a number of other parts that broke in this first test flight, but once the kinks are worked out, it should be possible to set some flight records.
Going Beyond The DIY & Model Aircraft World
While this video was fun to watch, there’s still not much utility in this plane design. Once they’re done, it will keep itself in the air for a long time. Perhaps a later version with more solar and more battery will do what NASA test planes have done and fly almost indefinitely, but it’s still just flying itself around, right?
However, hobbyist experiments like this have a way of finding their way into very serious things. We aren’t sure for how long human beings have been using tools, but it’s an instinct for us, and not all of the uses are fun, pretty, or peaceful. On the positive and inspiring side, this technology could be used to study weather, provide us with better 3D maps, or beam internet into areas that don’t have it without the cost and light pollution issues with satellite constellations. On the negative and frightening side, it could be used to carry drugs, explosive charges, and other things people don’t want for thousands of miles while being almost invisible to radar.
Either way, you can bet this isn’t the only small-scale low budget workshop doing this kind of work, and it’s going to be interesting to see what emerges!
Featured image: a screenshot from the video embedded in the article.
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