Precision Agriculture: A Day on the Farm

Drones are often touted for their ability to benefit farmers through precision agriculture, but solving real-world problems requires a more carefully considered approach—and spinning propellers only represents a small fraction of the work to be done.

Even within the professional uncrewed aircraft systems (UAS) industry, there is a tendency to regard precision agriculture applications as a one-size-fits-all proposition. You fly your drone over a farmer’s field with a weird, expensive camera that has five lenses, plug the resulting images into an expensive piece of software, and you get a false-color map of the crop with green, yellow, and red areas reflecting plant health.

Dr. Joe Cerreta (left) and Dr. Scott Burgess traveled to Turnbull Farm in central Oregon to use UAS to study threats to the region’s hemp crop.

This, in turn, is meant to tell the farmer where more water or fertilizer is required. In theory, that’s great. In the real world, however, the problems tend to be a little more subtle and complex. That’s what I found out when I spent a day on the farm with my friends Dr. Joe Cerreta and Dr. Scott Burgess of the Embry-Riddle Aeronautical University Worldwide Campus Department of Flight.

Dave Turnbull’s farm in central Oregon is home to 8,000 lush, green hemp plants, as well as a few intruders that could ruin his entire crop.

It turns out that after practicing agriculture for the past 3,000 years, farmers have gotten pretty good at figuring out where they need more water and fertilizer. They do have urgent problems that UAS may be able to help them solve, but only if you’re willing to listen to what they actually have to say. For their study of agricultural applications of UAS, Joe and Scott listened to Dave Turnbull, a farmer in central Oregon with five acres in hemp—more than 8,000 plants, in all.

This is what he had to say: “We’ve discovered about four male plants in our crop, and that’s about average for a crop of our size. You don’t want to have any male plants in your field—they create a pollen sack which releases pollen and fertilizes all of your other plants. At that point, your plants will stop producing the flower, which is the part you are looking for in terms of CBD content.

“Not only could that damage our crops, it could damage the crops of all of our neighbors, as well, because the pollen can travel up to five miles.”

The second problem confronting Turnbull’s fragrant farm is a tiny insect called a “leafhopper.”

“The leafhopper is new to central Oregon,” he said. “Apparently, there was a small problem with it that was discovered on beets. The leafhopper picks up a virus from the beets, ingests it and then spreads it to everything else.”

Once infected, a hemp plant demonstrates a distinctive symptom called “leaf curl,” which tends to degrade production, so early detection and treatment would be a huge benefit. Finally, to add insult to injury, the leafhopper doesn’t even enjoy the taste of hemp, so after taking a bite or two, and infecting the plant, it moves on to another plant, infecting it, as well.

In order to make accurate measurements about plants based on the light being reflected from them, it is necessary to gather information about the intensity of the light falling on them. That is the purpose of the sunshine sensor located on top of the Parrot Bluegrass.

Drones are not yet as common as tractors on farms, but that may change if UAS are able to deliver useful information that help farmers make better decisions and improve crop yields.

Hunting the Hopper

No surprise: the farmer knows his crop. The real question is, can drones do anything to help with either of these problems. That was what Joe and Scott intended to find out when we arrived on a bright, sunny day at Turnbull’s farm. The hemp plants were lush and green, laid out in perfect rows separated by patches of bare soil. Meticulous attention and plenty of hard work kept the field weed-free, without the use of herbicides.

In this effort to detect leaf curl, Joe planned to deploy a Sequoia multi-spectral camera: the one with five lenses.

“What we’re trying to find out is whether a UAS with this particular camera can detect a difference between the health of these plants, and then we will conduct further analysis to see whether or not those differences can be attributed to the disease—or not,” he said.

The reason multi-spectral cameras have five, or more, separate lenses is because each one detects a narrow band of light, referred to as a “spectra.” The Sequoia sensors captures images in the red, green and blue spectra, which we are all familiar with from daily life on planet Earth, as well as two that aren’t as familiar: red edge and near infrared.

The red edge spectra lies right at the limits of human perception, where the very darkest shade of the color that we know as red passes into the invisible world of infrared light. The near infrared band lies just a little further beyond that. It’s important to realize that this is not the same infrared light that is detected by thermal imaging cameras, which are carried on board drones for search and rescue missions, for example. Those detect long-wave infrared emissions, which are much further down the spectrum.

The data captured by these cameras is used to determine the health of a plant by comparing the relative level of light reflected by the plant across these different spectra. A healthy plant reflects a lot of green light—which is why plants look green to us—and absorbs a lot of red light. In the infrared spectra, they reflect an enormous amount of light. If you were an alien who could perceive near infrared frequencies, gazing upon Earth plants would be blinding.

However, a plant that is less healthy will begin absorbing more green light and reflecting more red light, which is why we perceive dying plants as turning yellow. Also, in the infrared spectra, weakened plants begin to absorb more infrared light, as well. Bad news for our crops, but good news for our alien visitors, who can now comfortably take off their sunglasses.

When you see one of those false-color multi-spectral images of a farm field, you know those green, yellow and red patches reveal the ratios between the different spectra of light being reflected by the plants and, thus, their health relative to one another.

The success of Joe’s idea, to use a multi-spectral camera to detect leaf curl, would depend on two things. First, does the disease process reduce the health of the hemp plant sufficient to alter the relative level of light being reflected from it across these different spectra? Second, does it impact the plant in such a way that it creates a unique multi-spectral signature?

Whereas the human eye perceives colors across the entire visible-light spectrum, multi-spectral cameras detect only narrow bands of light—called “spectra”—as well as several additional bands in the near infrared spectrum.

Seen here in a magnified photograph, the leafhopper is a cousin to the much larger grasshopper. Its primary threat to crops lies in its ability to transmit diseases between individual plants.

A DJI Inspire 1 equipped with a ZenMuse XT thermal imaging camera surveys a hemp farm in central Oregon, as part of research performed by Embry-Riddle Aeronautical University.

A Different Light

If you were hoping for definitive answers to those two questions, I have some bad news for you: actual science is a time-consuming process. The flying, which only took a few hours in this case, is the easy part. The real work began once Joe got back to the lab. Of course, when you do get back to the lab, it’s nice to know that your data is reliable.

An essential piece of that puzzle is understanding that the light reflected off of the plants is affected by the light falling on the plants. The “color temperature” of the sun’s light—that is, its hue—changes depending on whether the sun is directly overhead or low on the horizon, whether the sky is clear or overcast, and whether there is dust, smoke or haze in the air.

If you don’t account for the quality of the light when you capture multi-spectral images, it is impossible to make meaningful comparisons across multiple measurements through time. Fortunately, there are a pair of solutions that help us solve this problem.

First, on top of an aircraft carrying a multi-spectral camera, you will typically find an opaque square of white plastic, which is the sunlight sensor. During the flight, it collects data regarding the intensity of the sunlight falling on the crops to that data can be normalized for the intensity of the light.

Second, before each flight you should calibrate the multi-spectral camera using a “reflectance board.” This accessory is basically a plastic board that comes with the aircraft and provides a known color value. By comparing the result of the calibration image captured in the field to this established target, the camera is able to account for changes in color temperature caused by the local environmental conditions.

In addition to the work Joe was doing to use multispectral imaging as a solution for identifying leaf curl, Scott wanted to test an entirely different approach: visible light imaging. Like it says right in the name, is virus has a visible manifestation: the leaves curl up in a distinctive manner.

Using a DJI Mavic 2 Enterprise Dual for its visible-light capture capabilities, he flew a conventional orthomosaic mapping mission capturing hundreds of individual photos of the field. Back in the lab, he uses Pix4D to combine them into a single, seamless image.

“Once we’ve got that put together, the hope is that maybe we’ll be able to apply some sort of artificial intelligence, to be able to sense where those things are,” explained Scott.

Dr. Joe Cerreta holds a Parrot Bluegrass drone above a reflectance board to calibrate its multi-spectral camera system.

Flying is just one small part of doing science with drones. Analyzing and understanding the data that they capture is the more complex and time-consuming part of the work.

A reflectance board is included with the Parrot Bluegrass agricultural survey drone, to calibrate its multi-spectral camera based on current lighting conditions.

Images captured using a multi-spectral camera can be used to create Normalized Difference Vegetative Index (NDVI) maps of crops. In this preliminary result, scientists from Embry-Riddle Aeronautical University seek to distinguish between plants infected with a virus and their healthy neighbors.

Late in the growing season, male hemp plants reveal themselves by the appearance of pollen sacks. If they are allowed to burst, they can fertilize other hemp plants up to five miles away and degrade crop yields.

The Heat is On

Of course, finding a better way to combat leaf curl was only one of the missions that farmer Turnbull had set for my Embry-Riddle colleagues. The second was to find a way to identify male hemp plants, so that they could be removed before they released their pollen into the air, potentially ruining not only Turnbull’s crop, but those of his neighbors, as well. This was another project that Scott took on during our day on the farm.

The male plants tend to reveal themselves very late in the season, “he said. “From what we’ve heard in field reports, the male plants will actually change their temperature by a degree or so.”

In this case, we’re talking about the actual, physical temperature of the plant, like you would measure with a thermometer — as opposed to color temperature. This required a third type of sensor: a thermal imaging camera, which reveals differences in heat the same way a conventional camera reveals differences in light.

These are widely used in public safety applications, to reveal the presence of a person who is lost or hiding by their emitted body heat.

To achieve specific, reliable results, Scott would need to deploy a radiometric thermal imaging camera. “Radiometric” sounds like something a frantic scientist might be shouting about 30 seconds before Godzilla breaks the surface of Tokyo Bay: “Radiometric readings are increasing rapidly! We must notify the prime minister!” However, all it really means is the ability to take measurements at a distance.

A radiometric thermal camera can reveal the temperature of objects in the environment, not just whether they are warmer or colder than the surroundings. If you’re looking for a missing hiker, it’s enough to see their body heat against the snowy backdrop. However, if you’re looking subtle variations in the temperature of individual plants in a hemp field, you might want to know their actual temperatures.

Ironically, the hardware employed in radiometric and non-radiometric cameras is identical. The difference—and the added expense—comes from the fact that the radiometric camera has been painstakingly calibrated so that the temperature value it returns for each pixel is reliable, within established parameters.

Flying is just one small part of doing science with drones. Analyzing and understanding the data that they capture is the more complex and time-consuming part of the work.

Using a collection of two-dimensional photographs along with photogrammetry software from Pix4D, the Embry-Riddle faculty were able to create a 3D map of the farm down to the level of each individual plant.

The Embry-Riddle scientists deployed the Mavic 2 Enterprise Dual for its visible-light capture capabilities. Its built in thermal imaging camera lacks the resolution that would be required to look for temperature variations between the plants.

Flying for Science

To gather thermal data, Scott deployed a DJI Inspire 1 with a ZenMuse XT camera gimbal, even though it might be too limited for the type of data he was hoping to gather.

“One of the issues we have is getting the right sensor,” said Scott. “In some cameras, that radiometric capability is right in the center of the sensor, so you’ve got to directly above that male plant in order to get a result. It would be better to have a sensor with a broader perspective with that radiometric capability.

“Carrying that type of sensor requires a different aircraft, so that why this becomes a longer-term research project. We need to be able to obtain the all of the right equipment — and that takes time.”

Scott hoped that the his preliminary flights during the day of our visit to Turnbull Farm would guide those future efforts, by helping to establish the best altitude above the plants to fly a thermal survey mission, for example.

Once again, our trip to the hemp field had proven that even with a fleet of drones equipped with different types of sensors, solving the real-world problems of farmers takes more than technology — it requires an understanding of the issues they face and how, or whether, that technology can deliver useful results.

Text & Photos by Patrick Sherman

The post Precision Agriculture: A Day on the Farm appeared first on RotorDrone.

SOURCE: RotorDrone – Read entire story here.

FoxFury 3060 Drone Light

The next time you are out flying a mission during civil twilight, or under a daylight waiver to 14 CFR Part 107, spare a thought for the people who design your beacons. As drone pilots, we demand a lot from our strobes: they should be bright as the sun, light as a feather, tough as nails, cheap as dirt, easy as pie, smaller than a postage stamp, and flash for days on a single battery charge.

Equipped with a pair of FoxFury D3060 lights, a drone soars into the darkening sky of civil twilight, in full compliance with 14 CFR Part 107.

Of course, that combination of attributes cannot be achieved in this material reality: The laws of physics simply won’t allow it. Longer endurance means a bigger battery, which increases weight. A brighter beam means a bigger lamp and more bulk. A rugged housing increases both size and weight, as do user-friendly controls. All of this means that designing a drone strobe involves a series of tradeoffs, and no single configuration will be optimal for every application.

That said, FoxFury has made a whole series of fine choices in developing its new D3060 drone light, creating a strobe that is well-suited for the overwhelming majority of small Uncrewed Aircraft System (UAS) operations.

Let’s start with the basics. The D3060 actually incorporates two separate lamps: one facing forward and one on top. They can be individually controlled and set for continuous high- and low-intensity beams, as well as a high-intensity strobe. At peak output, each emits a full 200 lumens, satisfying the three-mile visibility requirement under 14 CFR 107 for civil twilight and nighttime operations.

The unit is powered by an internal battery, recharged using a standard USB-C connector. Depending on your specific combination of settings, the D3060 will run for one and a half to three hours on a single charge. It is waterproof and shock resistant, and incorporates a wealth of features that make it simple and intuitive to use.

QUICK SPECS

Model: D3060
Manufacturer: FoxFury (foxfury.com)
Type: Dual-lamp strobe light
Weight: 37 grams
Dimensions: 33x58x23 mm
Attachment: 3M Dual Lock Fastener
Fire Resistance: NFPA 1971-8.6 (2013)
Run Time: 1.5 to 3 hours
Recharge Time: 1.5 hours
Color Temperature: 5,700 K
Price: $59.00

Quality of Life

Steve Jobs made Apple a consumer electronics legend with a relentless focus on the end user’s experience of his company’s products—something known today to as “quality of life” in software development circles. That isn’t a concept that frequently rates as important among drone strobe users, but FoxFury delivered it nevertheless. When you connect the D3060 to its included recharging cable, a red LED lights up to let you know it’s receiving power, and then it turns green when the charge cycle is complete. It’s a small feature, but it’s reassuring to know before you are heading out for an important night operation that your strobe is indeed fully charged.

Each of the two lamps on the D3060 is controlled by its own simple pushbutton: push it once and you get a full-intensity, steady beam; push it again and you get a low-intensity, steady beam; push it once more and you get a full-intensity strobe. A fourth push turns it off. It’s easy to set the configuration you want in seconds.

If I were to offer a suggestion for future models, it would be that FoxFury emboss either button with a letter “F” or a letter “T,” so you know which emitter you are going to power up before you actually press it. I dazzled myself several times during testing by looking down at the light while I thought I was turning on one lamp, facing away from me, when it turned out I was actually turning on the one pointed directly at my face. I will say this: it is very bright!

Developed for use on small UAS, the D3060 from FoxFury is also suitable for wear on helmets and other personal protective equipment.

The FoxFury D3060 base plate is made of rugged nylon, and it can swivel a full 360 degrees to accommodate different mounting options.

Each of the FoxFury D3060’s two lamps has a maximum output of 200 lumens, sufficient to meet the requirements of operations during civil twilight under 14 CFR Part 107, as well as nighttime operations occurring under a waiver.

One handy feature of the FoxFury D3060 is the inclusion of colored LEDs to indicate charge status. Red means charging, and green means the internal battery is fully charged.

Making Connections

Another example of where attention to detail in the design of the D3060 pays dividends is in the mounting options that are available for the unit. Each light arrives with two adhesive-backed squares of 3M Dual Lock Fasteners, which are surprisingly strong: both sides are all hooks, all the time.

The base of the D3060 is designed to accommodate a square of Dual Lock Fastener, while the other square is attached to your drone. The base also swivels 360 degrees, allowing you to adjust the angle of the light for your particular mission. In addition, it includes a pair of slots for alternative mounting options, such as a cord or strap. These mounting options allow the D3060 to be used in other applications besides drones, such as helmets, safety vests, and other personal protective equipment.

Constructed with polycarbonate, nylon, and silicone components, the D3060 is extremely rugged. It’s fire resistant, works while submerged in water, and can sustain a fall from 10 feet onto a hard surface. Basically, it will still be working after just about any drone it’s attached to is wrecked—as tough as a drone strobe needs to be.

The FoxFury D3060 comes complete with the light itself, as well as a pair of adhesive-backed squares of 3M Dual Lock Fasteners, and a USB-C cable for recharging its internal batteries.

The D3060 drone light from FoxFury has multiple mounting options, including 3M Dual Lock Fasteners and slots to accommodate straps and other connectors.

The full intensity of the FoxFury D3060’s twin lamps are limited to a 60-degree cone. Beyond that, visibility drops off rapidly.

Lighten Up

At 37 grams, the weight of the D3060 is almost negligible, even on small commercial drones. Testing it on an industry-leading platform from a well-known manufacturer, I found a five-second difference in flight time, depending on whether or not the light was attached. If you fly missions where that is a meaningful margin, you definitely need to step back and reevaluate your operating parameters—you are flying way too close to the edge to be safe.

Something I did notice while testing the D3060 is that there is a cone, about 60 degrees wide, where each of the lamps is at its brightest. I verified this using a protractor. Then I found that FoxFury lists this fact among the specifications on its website. By the letter of the law, that isn’t a problem. FAA regulations for operations during civil twilight make no mention of a required viewing angle for your strobe.

That said, it did prompt me to wonder: What if a crewed aircraft was approaching your drone at a 90-degree angle? The pilots would likely not spot your drone until they were much closer than the requisite three miles, creating a potential conflict. Fortunately, this issue can be at least partially offset by simultaneously using both lamps.

Another factor that might be a drawback for some pilots is the price: $59.00. Can you purchase a working strobe for less than that? Absolutely. Will it check all of the same boxes as the D3060, especially when it comes to being lightweight, robust, and easy to use? Probably not. The D3060 offers a solid balance of features for pilots who want to know they have a reliable solution in their hands that they can count on, even under adverse conditions.
TEXT AND PHOTOS BY PATRICK SHERMAN

While drone strobes are most often regarded as night flying accessories, they can also be a big benefit during daylight operations, making it easy to identify your aircraft even against a cluttered background.

Daylight Operations

During my testing, I discovered another important fact: Strobes are nearly as useful during daylight hours as they are at night. Crewed aircraft use their anti-collision lighting around the clock, and perhaps that is something we drone pilots should be doing, as well. Not only would it make it easier for other air traffic to spot our machines, but it makes it easier for us to keep track of them as well.

Having a strobe on board makes it easy to spot your aircraft against any type of background, and may also significantly enhance your visual line of sight under certain lighting conditions. If you haven’t flown with a strobe during the day, you owe it to yourself to give it try. You might be surprised at what you’ve been missing.

Not only is the D3060 from FoxFury fire resistant and capable of sustaining a 10-foot drop onto a hard surface, it even works underwater: all conditions that would likely ruin any drone that is carrying it.

The FoxFury D3060 recharges its internal battery using a standard USB-C cable, which is included with the kit.

The post FoxFury 3060 Drone Light appeared first on RotorDrone.

SOURCE: RotorDrone – Read entire story here.

Flying Under the Midnight Sun – High Arctic drone operations

“This is a crevasse minefield!” yelled Louise. In flat light I was skiing in front, trying to pick the safest way forward. Bumps of blue glacier ice were all around me. My ski tails would settle, leaving behind holes of blackness. Louise moved left to avoid one of my holes. Dave also stepped left into untracked snow. A yell from Dave warned us that he was falling into a crevasse. Louise and I threw ourselves to the snow, bracing for the jerk on the rope. I looked over my shoulder to see Dave windmilling his ski poles but still visible—then he was out of sight, with just the baskets poking out of the crevasse. Then, in horror, I saw the baskets disappear and the 150-pound sled slowly get sucked into the crevasse on top of him. I called back to Dave. No answer. Now the weight, equivalent to two bodies, was pulling on Louise.

The red area is the Nunavut Territory, Canada. Ellesmere Island is the large red northernmost island in red.

Six days earlier, in late May, our three-person team of Dave Critchley (Chair of Biological Sciences, School of Applied Sciences, Northern Alberta Institute of Technology), Louise Jarry and I had been heading by chartered Twin Otter ski plane from Resolute Bay at Cornwallis Island in Nunavut, Canada to the Prince of Wales Icefield on Canada’s Ellesmere Island’s southeast coast. Winter cold had broken about a week before, giving us weather that was 20 degrees Fahrenheit, which was warmer than the norm. Our starting temperatures were more like what was expected at the end of a month-long Arctic ski tour. The two-plus hour plane flight treated us to some amazing views: jagged coastal cliffs of Devon Island’s Colin Archer Peninsula, followed by the inky blue open waters of Hell Gate Polynya, and then the frosting top of Sydkap Ice Cap, where we had skied across two years before.

Our expedition, Ivory Gulls and Nunataks—Ellesmere 2019, would ski through a portion of the Prince of Wales Icefield checking for activity at ivory gull nesting sites last surveyed in 2009. The word nunatak is from the Greenlandic Inuit, meaning rock outcrops or peaks surrounded by glaciers. The population of the ivory gull in Northern Canada has dramatically declined in the last several decades, and many nesting colony sites farther south, in the Manson Icefield, had already been abandoned by 2009. We decided to focus our survey efforts at the sites that last supported nesting birds. All previous nesting surveys had been done by helicopter. We would ski site to site and use a spotting scope and drone to check for birds and count them.

Our expedition was in search of nesting sites of Ivory Gulls.

During our expedition planning, we corresponded with numerous High Arctic researchers and videographers and asked them about their drone flying experiences and equipment recommendations. Alarmingly, everyone who had attempted drone flights north of 70 degrees latitude had horror stories. Some common themes emerged: out-of-control drones spiraling around pilots, or flyaway drones that were never seen again. These issues were often with early generation DJI Phantoms.

According to the experienced operators, the root of these problem flights revolved around lack of strong GPS signal and compass errors. The phenomenon is nicknamed the “toilet bowl effect” for the swirling drone motion as your dollars are flushed away. My experience with GPS signals in the High Arctic has been completely different, at least from a ground navigation point of view. For example, there are always more and stronger satellite signals in the North compared to the Canadian Rockies.

The ALLPOWERS 80-watt folding panel charging away during a snow storm.

THE GEAR

We decided to bring two DJI Mavic 2s, a Zoom and a Pro model. Going that far north with only one drone seemed too risky. If one crashed, then at least we could use the same batteries in the second. A local DJI retailer, MultirotorHeli of Calgary, Alberta, did not think we would have problems flying up North—easy for him to say.

The Mavic 2 Pro/Zoom user’s manual has a number of statements that certainly did not boost our confidence; “The Mavic 2 cannot use GPS within polar regions. Use the Downward Vision System (DVS) when flying in such locations.” OK, we read up on DVS in the manual, and again, the news was not rosy: “The DVS may NOT function properly when the aircraft is flying over water or snow-covered areas.” Our entire trip would be on glaciers that were completely snow covered. The manual further stated, “Operate the aircraft cautiously when in any of the following situations: flying over monochrome surfaces (e.g., pure white), highly reflective surfaces, surfaces that strongly reflect or absorb infrared waves, or surfaces without clear patterns or textures.” Just about all of those surface descriptors equal a snowy glacier.

Along the way, we were given advice that flying in attitude mode (ATTI) would circumvent the need for compass or GPS inputs. Mavic 2 does not have a mode switch like the Phantom 4 that allows it to shift into ATTI. In consulting user groups, such as mavicpilots.com, it seemed that sport or tripod mode could be remapped using DJI Assistant 1.1.2 to become ATTI (in developer tools). Despite numerous attempts to follow instructions given by followers of the user group, the mapping protocol would not work for us. We even tried covering the aircraft top in foil in the hope that we could block GPS signals and force it into ATTI, but had no luck.

We prepared ourselves for the scenario that our drones would be totally useless, like paperweights being dragged around behind us for a month.

The 12-volt storage battery is inside the box with a voltage regulator on the outside. It weighs 2 kg.

BITTER COLD

The next major hurdle was cold weather operation. During trials in subzero temperatures in Alberta we quickly discovered that our phones were the weakest link. Their thinness and small batteries made for quick heat loss and shutdown. On our first or second flights ever, we learned that if a phone dies after takeoff, you can still control and operate the drone using line of sight along with the controller LCD display. An old, weak cell phone battery is worth replacing for cold weather flying. We bought reusable gel heat packs and built a tablet-sized plywood holder to sandwich the phone and heat pack, and used a PGYTECH Sunshade.

Taking off from the Wykeham Glacier.

A critical selling point for us with the Mavic 2 is the fact that the Mavic Enterprise self-heating batteries can be used on the Pro/Zoom models as well. Used on a non-Enterprise model, the self-heating batteries can only be used by manually starting the heating function. Luckily, we had five batteries between the two drones, since two of the Enterprise batteries developed bent contacts after only one use, which prevented us from using them again. (The drone and charger contacts were in perfect shape, so how the recessed battery contacts were bent is still a mystery.)

One final showstopping logistic to be worked out was how to reliably charge drone batteries and the controllers. Using our experience from previous Arctic ski trips, we knew that a well-tested system of a small solar panel with storage battery could charge satellite phones, DSLR, InReach, and cell phone batteries. The DJI Mavic2 intelligent batteries proved to be much trickier. First, they are higher voltage and amperage than any previously used battery products. Second, the acceptable charging range using the DJI 12-volt car charger is very narrow.

A PGY Tech sun shade was very useful for strong low angle sun.

Dave sought advice from his school’s Alternative Energy Technology program. They suggested we use an ALLPOWERS folding 80-watt solar panel (1.8 kg, 110 x 60 cm open; 35 x 19 x 9.5 cm folded). With 24-hour sun during our expedition, batteries could be charging all night while we slept, or we could open out the solar panel on a sled as we pulled it by day. Field testing revealed the DJI intelligent battery charges in a very narrow range. If the sun angle and or intensity changes too high or too low, the charger shuts off. The only way to practically overcome that charger sensitivity was to place a storage battery between the solar panel and the 12-volt auto charger. The panel charges the storage battery in an unregulated way, as sun angle and cloud density change all day and night. Then, using a regulator attached to the storage battery (2 kg total weight, with 2.9 Ah lead acid), we could output precise voltage to the 12-volt auto charger and the intelligent battery.

THE JOURNEY BEGINS

Upon arrival in Resolute Bay, Nunavut Territory, Canada (latitude 74 degrees North), we conducted several brief flights. If things went sideways here, there would be little need to take our paperweights on a ski tour for a month. The DJI user manual states to calibrate the compass if flying at a location farther than 50 kilometers away from the location the drone was last flown. Working by the philosophy, “If it ain’t broke, don’t fix it,” we had not calibrated them in southern Canada, so these two drones had a factory calibration in China, which was 8,000 kilometers away and 42 degrees of latitude change north. Nevertheless, our test flight performance was flawless. The Mavic 2s operated perfectly and we had a green light for operating farther north.

After several days of waiting for suitable flying weather, we made our two-plus hour charter flight. The remoteness of our trip sank in as we flew. During the entire flight we never once crossed a road or passed over a village or permanent habitation. Our intended ski plane landing site was riddled with crevasses, so the pilots nixed the area. Our alternate spot was 12 kilometers away in a gentle bowl of powder snow. Landing uphill in powder, it didn’t take much distance to stop the plane.

Over the next week, we skied our way across a major unnamed glacier. During the summer, the meltwater flowing on the surface of the glaciers carve canyons into the ice, creating whitewater torrents that are impossible to cross. Some in this area are 50 kilometers long! For us, during spring, the canyons are still significant barriers. They can be 20 to 30 meters across and 10 to 15 meters deep, with overhanging snow drifts along their lips. As we skied up to our first canyon the question was whether to turn left or right to find a snow bridge, or to ramp in and out. Although the drones were brought for seabird detection, we wasted no time launching them for recon missions to help us know which way to cross the canyons. Many hours were quickly saved by knowing the correct path to ski across the canyons.

Roped up glacier travel, above left skier (Louise) near the pass is where we were dropped off by the ski plane.

Crevasse icefall on the upper south branch of the Trinity Glacier. This terrain is way too dangerous to attempt pulling a sled.

Goggles with facemask attached to prevent frostbite from wind chill.

View of typical campsite arrangement, note the solar panel on top of left tent.

Dave surveying mountain for sign of ivory gull nest site on our first evening.

Dave and Louise ski back to camp after climbing our first mountain.

CREVASSE FALL

A week into the ski trip, we descended to Wykeham Glacier. Immediately, we could see the character of this glacier was different than previous ones we had been moving across. Crevasses were evident everywhere, both obvious open cracks as well as slight shallow depressions, indicating sagging snow bridges over blackness. Crevasses form when glacial ice cannot bend more, resulting in breaks that extend down tens of meters or more. Think of it like a cold Mars or Snickers candy bar: At first you can bend the bar and the layer of chocolate on top stays intact, but at a certain point the chocolate coating cracks open to expose the inner layers. If all crevasses stayed open, it would be harder to accidentally fall into one, but drifting snow and ice closures continually cover the slots and form hidden trap doors that might collapse with the weight of skis or boots.

Dave was rescued from the crevasse unharmed, although he just barely dodged the 150-pound sled landing on top of him. Ice screws, rope, pulley work, and a couple hours of sweat were needed to get him and the gear out of the hole. The ALLPOWERS solar panel had been strapped to the top of the sled that day. Hauling the loaded sled out of the crevasse was the hardest work. There was no way to pull it out on its bottom-sliding surface; it came out upside-down over the ice on the solar panel. We fully expected the solar panel to be trashed, and therefore there would be no more drone flights once batteries were exhausted. However, despite this very rough treatment, the solar panel was still working!

Drone view looking down the Wykeham Glacier, camp near bottom right corner, meltwater canyons are the long furrows.

Dave looking out of the crevasse he fell into and happy to be out of his hole.

First drone flight on Ellesmere Island. Next to Dave are the ski tracks where the plane landed and took off.

Selfie using Olympus TG5 waterproof camera duct taped to ski pole looking up a seal hole.

Using the parka hood helps create shade in bright conditions.

Drone view over southern branch of the Trinity Glacier.

Pilot Kenn Borek’s Twin Otter on skis taxies up the glacier dome to pick up our team.

HEADING HOME

The crevasse fall was a serious wakeup call to us: we needed to very carefully select the safest route on the glacier to avoid as many of the crevasses as possible. We developed a routine. After setting up camp and finishing supper, we’d launch several drone flights to scout the next day’s potential routes. Flights to four previously documented ivory gull nesting sites did not find any activity. Our drone recon missions revealed a direct path to additional sites two days away; they were peppered with hundreds of visible crevasses. Never mind the many more hidden ones. A one-week detour west across and over a gentle icecap was the only way forward.

By the beginning of June, our nearly flawless weather began to break down. We spent three days in camp playing cribbage while 25 centimeters of fresh snow buried all signs of previous sagging bridges. An InReach forecast predicted June 6 would be the only clear day for the next five to seven days. We had to schedule that day for a ski plane pickup or risk missing our scheduled commercial flights south.

The Twin Otter ski-equipped plane circled a couple of times, then descended into the glacial basin to our north, out of sight. Silence followed. After what seemed an eternity we heard the engines revving, then silence, then more revving. Just as we were about ready to launch a drone to investigate, a shark fin appeared from down slope. The tail rudder materialized as the plane climbed its way up the glacier while plowing through deep snow. The plane had landed on the closest sun-lit patch of glacier and had been taxiing many kilometers on its skis, weaving around crevasses to make its way uphill to our camp.

We didn’t see a single ivory gull, so the search for their known nesting sites was a complete bust. However, the utility of small, foldable quadcopters for photography, ski route selection, and terrain hazard assessment in the Arctic proved a huge success. Although the Mavic 2 worked without a hitch for us to latitude 78 degrees, and to 82 degrees North for another pilot in 2019, a cautionary note should be made: There are large ore bodies in the North that will leave compasses spinning. When you’re flying in such an area, all bets are off. Be prepared and able to fly in ATTI mode.

The Ivory Gulls and Nunataks 2019 team, Dave, Greg, and Louise, with the Twin Otter plane.

Drone view of an unnamed peak on the left we skied to the top of.


DIY Arctic Phone Holder

Start with a wood frame with elastic straps.

Add a heat pack.

Insert a thin foam protector.

Secure your phone in place.

A sunshade makes it easier to see your phone’s display.


7 Tips for Flying in the Cold & Snow

ONE
Read Your aircraft’s users manual. Be familiar with the manufacturer’s specifications with regard to the operating temperature range. This includes range of the controller and batteries. Know the charging temperature range of your batteries. Batteries that are too cold will not charge correctly or may be damaged. Make short test flights in cold weather until you gain understanding of how your aircraft and associated devices handle the cold.

TWO
Keep Batteries Warm. Before use, keep aircraft, controller, and phone and tablet batteries warm. If you are out in the field for hours or all day, keep components with batteries near your body or use a heat source to maintain batteries at room temperature. A fly fisherman’s vest with lots of big pockets can keep items organized under insulation layers. If that’s too bulky or awkward, try an insulated soft-sided lunch cooler bag with hot water in plastic bottles. (I suggest Nalgene brand, which can handle hot to boiling water.) Place those bottles in a sock or mitten when you first start to use them to ensure that a very hot bottle does not directly touch batteries or plastics.

THREE
Keep the Aircraft Cool. To prevent condensation or frost forming on your lens and sensors, don’t move the aircraft back and forth from warm to cold to warm. After the aircraft leaves home, your car, or warming bag, keep it in the cold until your flying is done for the day.

FOUR
Be Gentle with All Equipment. In order to shave weight and cut costs, much of drone equipment is made of plastic. The colder it gets, the more fragile everything becomes. Many components were never designed to be used below freezing. Go slowly and warm parts before flexing or bending.

FIVE
Use a Landing Pad. Collapsible pads are not just for dust and vegetation. Unless you are landing on bare ice, use pads to prevent snow from spraying on the lens, or the aircraft from bellying out in soft snow. Some aircraft use takeoff features to help with precise landing, and a distinct “H” will be much easier to find than acres of featureless white.

SIX
Use Neutral Density Filters. For smooth video display, a frame rate of 24 to 30 per second is common. The shutter speed should generally be twice the frame rate. In bright snow conditions using a camera with a fixed aperture, neutral density filters are an excellent way to slow down the shutter speed and reduce glare. Experiment with different densities before critical shoots and remember that time of day will change the density you need. A range of 4 to 32 (times reduction in light) will cover most situations outside of time-lapse shots.

SEVEN
Shade the Screen. It isn’t fun to squint and barely be able to see anything on the phone or tablet screen on a bright day in a snowscape. There are many devices on the market to help reduce glare and provide shade to your screen. The other options are monitor devices like DJI’s Crystal Sky or Smart Controller that have screen brightness higher than most phones or tablets. The other significant advantage of those devices is the large milliamp battery they use with low operating temperatures that uninsulated phones or tablets can.

By Greg Horne Photos by Greg Horne, Louise Jarry & Dave Critchley

The post Flying Under the Midnight Sun – High Arctic drone operations appeared first on RotorDrone.

SOURCE: RotorDrone – Read entire story here.