Pros and Cons of Drone Mapping Using Fixed Wing Drones
Out of all the industries that have benefitted from drone technology, mapping has to be the one that has improved the most in terms of efficiency and speed. No longer do surveyors have to travel long distances and set up several ground control points. Nowadays, advanced drone mapping technology has allowed surveyors to map vast tracts of land at a fraction of the time and effort it took to do the same job in the old-fashioned way.
While most commercial drone applications have been dominated by rotary wing drones, mapping is probably one of the few industries that still rely heavily on fixed wing drones. What is it about fixed wing drones that make them particularly attractive to surveyors? Read on as we analyze the benefits and limitations of fixed wing drones in mapping jobs.
The industry of drone-based mapping
It’s easy to see why drone technology has been an instant hit in the mapping industry. Instead of surveyors walking along huge tracts of land, or camera equipment being loaded into a helicopter, all the work has been reduced to drones autonomously flying over the survey area and collecting data. Not only did surveying jobs become easier and faster, but data accuracy has improved as well. With drones able to take overlapping images, data processing virtually needs to do zero interpolation between separate observation points. The high-quality images produced by drones, even those with 12MP cameras, produce high resolution images that are a huge upgrade from the products of the older methods.
Drone technology has also allowed mapping jobs to be done at a lower cost. Being a faster process, there are less man-hours needed to finish a drone-based mapping job. Where the old method of capturing images involved renting a helicopter, drone mapping will only need the drone itself supported by a ground crew.
Mapping surveys using drones are not limited to photogrammetry, or the use of aerial photos to generate maps. More complex mapping jobs, such as LiDAR surveys and thermal imaging, can also be done using drones. These will involve more sophisticated and expensive equipment. They are also more technical nature and will require additional skills for data processing. As a commercial activity, these complex mapping surveys can also generate higher income.
Why use a fixed wing drone?
The benefits of using a fixed wing drone lies in the physics of how it flies. In contrast to rotary wing drones that use propellers to generate lift, the wings of a fixed wing drone generate lift as it moves forward. This mechanism has a few implications on what a fixed wing drone can and cannot do.
1. Longer flight time
Fixed-wing drones can fly farther and longer on a single battery cycle than their rotary wing counterparts. With the propellers working only to provide forward propulsion, fixed-wing flight is a much less power intensive activity. When mapping very large or linear areas, fixed wing drones are more ideal as they can cover larger areas without having to go back home for a battery replacement.
2. Optimal for linear survey
There are several drone mapping or inspection applications that are confined within a single long corridor such as inspection of pipelines and powerlines, and mapping of shorelines. Fixed wing drones perform exceptionally well in these surveys. With little need for maneuvering, fixed wing drones can very quickly cover long stretches of a linear area.
3. Better stability
Compared to rotary wing drones, fixed wing drones are more stable in extremely windy conditions. Many quadcopters can tumble right out of the sky with a strong wind, but at worst, a fixed wing drone will probably just veer off course.
4. Recovery from power loss
When a rotary wing drone loses power, it will plop down to the ground like dead weight. This is far from the case for rotary wing drones. With their aerodynamic wings, fixed wing drones can glide gracefully even without propulsion. Altitude loss is also much slower. This means that the drone pilot still has time to position the drone to land in good spot.
5. Easy to maintain and repair
With fewer moving parts, the maintenance of fixed wing drones is much easier and less complicated than rotary wing drones. These drones have wings made of easily replaceable foam. The technology of fixed wing drones is very simple, and they do not need an array of sensors to fly.
Limitations of fixed wing drones
Despite all of the benefits of fixed wing drones, one has to wonder: why are rotary wing drones so popular? There are some very good reasons for this, as fixed wing drones also have several drawbacks.
1. Large takeoff and landing area
Similar to a plane, a fixed wing drone will need a small runway to properly take off and land. While it’s also possible to launch them by hand, this method is not as reliable and may end up damaging your drone. This is in contrast to rotary wing drones that can take off vertically from virtually anywhere.
2. Cannot hover
Fixed wing drones rely on the flow of air beneath their wings to generate lift. This means that they must always be moving to stay airborne. This aspect of flight eliminates the capability of a fixed wing drone to hover in place. Thus, fixed positions stills may be hard to capture. Taking multiple shots from the same angle will prove to be almost impossible with a fixed wing drone, not to mention it will involve a lot of maneuvering.
3. Less compact
To be able to generate enough lift, a fixed wing drone needs to have a large wingspan. This means that fixed wing drones are nowhere near as compact as rotary wing drones. There is probably not a single fixed wing drone model that can fit it in a backpack or a small suitcase. To bring a fixed wing drone in the field, you are probably going to have to put it in a car.
4. More expensive
With so many rotary wing drones flooding the market, fixed wing drones tend to be the more expensive alternative. While this is something that can change with dynamic market conditions, buying a fixed wing drone now could mean a high capital expense for your business.
5. Technically challenging to fly
Rotary wing drones, or quadcopters in general, have evolved to a point where flying one is so simple that a child could do it – even professional-grade drones such as the Phantom 4 Pro. Fixed wing drones will probably never reach this level of ease of use. They are not as easy to maneuver, they cannot suddenly change directions, and a drone pilot cannot simply stop the drone and hover in place while they get their bearings.
What are hybrid drones?
One of the most frustrating limitations of a fixed wing drone is that it needs to have a runway to take off and land. However, there is no argument that a fixed wing drone really excels as soon as it is airborne: it is faster, more stable, and can fly longer. With the goal of merging the strengths of fixed wing and rotary wing drones, some companies have developed drones that are a hybrid between the two drone types.
Also known as Vertical Take-off and Landing (VTOL) fixed wing drones, these drones have a propeller that provides lift, allowing them to take off and land vertically. Once airborne, these same propellers change orientation to provide horizontal propulsion. The result is a drone that can fly with the efficiency of a fixed wing drone but can take off and land anywhere like a rotary wing drone.
What are the best brands of fixed wing drones for mapping?
The biggest hurdle in using fixed wing drones for mapping is that there are not a lot of options.
The Aero-M Drone from 3DRobotics provides an all-in-one mapping solution for large areas such as farms, constructions, and forests. It has also been used for emergency response and search and rescue operations. With a tough but lightweight frame, the Aero-M can cover up to 250 acres in single battery cycle.
The Aero-M Drone comes with the Pixhawk Autopilot System that allows for easy planning and execution of automated flights. Data is collected using its onboard Canon S100 12MP camera. Bundled with the drone is the Pix4DMapper LT 3DR Edition software, which provides data processing capabilities and allows users to generate accurate georeferenced and orthorectified maps.
The Pro Ag variant of the Parrot Disco fixed wing drone is made specifically for agricultural surveys. With such a tool, farmers can quickly and easily assess the health of their crops using visual tools and generated normalized difference vegetation index (NDVI) maps.
The powerful motor and high capacity battery of the Pro Ag allows it to cover up 200 acres in a single battery cycle. It comes with a dedicated remote controller which can also be connected to a mobile device to provide live video feed using an optimized Wi-Fi connection.
Crop analysis is done by the Parrot Sequioa, a multispectral sensor that captures RGB photos using four separate bands. It also has sunlight sensor that records the intensity of light at any given point, an information which can be used to perform radiometric calibration for consistency of data across large areas.
The Skywalker X8 Flying Wing is a fixed wing drone that is designed specially for mapping jobs. Its wing span that measures more than 2 meters is dominated by foam wings that allows the X8 to carry up to 2 kg of payload. With this carrying capacity and a spacious cargo compartment, the Flying Wing can be equipped with a lot of custom mapping and photography equipment.
It does NOT come with its own camera. Some users have been able to get results by simply installing a Sony A5100 24MP camera coupled with dipole telemetry equipment to geo-reference all aerial images. A GoPro camera would also be a good add-on for the Skywalker X8, plus a customized 360° panning system.
Drone technology has revolutionized the mapping industry, allowing for mapping surveys to be done faster, safer, cheaper, and with more accurate results. Although rotary wing drones have become the more popular model, there is still a minority of drone pilots who prefer using fixed wing drones. Indeed, if there is a commercial drone application that will benefit from fixed wing drone technology, then it is the mapping and survey industries.
The chief advantage of fixed wing drones is that they can stay in the air longer in a single battery cycle. Combined with their faster flying speeds, fixed wing drones have the potential of finishing mapping surveys faster than rotary wing drones. This becomes even more pronounced when conducting surveys over large areas or over long corridors.
There are a couple of flight-related challenges when using fixed wing drones, such as the need for a runway to take-off and land. A possible deal-breaker for drone pilots is the lack of capability of fixed wing drones to hover in place, making it impossible to take shots from a fixed position. With the development of hybrid drones, perhaps this will not be an issue in the near future.
Another difficulty that will be encountered when choosing to use fixed wing drones is that there just aren’t a lot of them in the market today. They have largely fallen out of fashion, perhaps due to the technical demands of piloting fixed wing drones. With large drone manufacturers such as Yuneec coming up with their own fixed wing drones, perhaps they will be re-introduced into the mainstream soon.
We are certainly hoping that fixed wing drones get to experience a resurge in popularity. Once they gain mainstream attention again, innovations and technological evolution is sure to follow. As exhibited by the development of hybrid drones, there is still a lot of room for improvement for fixed wing drones. However, we are optimistic that the physics of fixed wing drone flight is the key to coming up with drones that can fly longer and farther without the need to double down on battery capacity.