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Fixed-wing drones: the evolution of the technology

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Over the past seven years, a massive shift has been taking place as unmanned aerial vehicle (UAV) use expanded beyond the military sector into commercial use. This shift began as multirotor drones opened professionals across industries to the possibility of gathering imagery and location data in a way, and at a speed, they had never done before. Yet as much as multirotors showed promise for surveying, they quickly presented a glass ceiling to users—using up so much power to stay aloft that they couldn’t handle large projects.

Multirotors, like the DJI Phantom, remain useful on smaller projects and for applications requiring hover functionality for imagery. But in cases of large mine sites, road projects, massive agricultural applications and city planning, customers searched for a system upgrade as a means to avoid so many battery swaps and so much time in the field. Drone developers anticipated this, and had a solution ready: the fixed-wing survey drone. 

How multirotor and fixed-wing drone lift differs

Because they are constantly in a hover mode, multirotors use large amounts of energy just to stay aloft, so they move slower when capturing imagery and are unable to fly for long durations. Fixed-wing UAVs require much less energy in cruise mode as they capture data. This is thanks to their wings, which encourages a passive lift, so they cover more ground, faster.

Fixed-wing drone advantages and rise to prominence

The secret to fixed-wing success has been its design. Whereas a multirotor constantly sucks loads of power from the battery to spin its propellers enough to generate lift, a fixed-wing only requires the energy needed to propel it forward. The lift of the aircraft is generated passively as its wings cut through the air at a specific angle. What this means is that these systems can fly much longer and cover much more ground than multirotors.

So leading fixed-wing producers, like Parrot and Delair, came up with fixed-wing solutions like the (2017-discontinued) Parrot Disco, the (Parrot) SenseFly eBee (2013-present) and eBee X (2019-present); and the Delair UX11 (2018-present). All of these were relatively compact and hand launchable, offering far more coverage than a multirotor in a single flight. No landing gear is required as they glide down to land on their belly. 

Hand launch of eBee X

A common launch option for classical fixed-wing drones, hand-launching gives an easy feel to operations yet involves some coordination and respect to avoid the blades of the drone.

Since fixed-wings were previously the only possibility for large-area coverage with reasonable data quality, resolution and accuracy possibilities, they proved useful on larger projects that would have taken much longer with multirotors and were sometimes impossible on foot. In fact, as they became more popular, a niche emerged that was once dominated by satellite data and manned aircraft. This is because they gather data at a higher resolution and stay below cloud cover while running safer surveys at a fraction of the cost.  

What is a fixed-wing drone?

  • Similar to a passenger aircraft, a fixed-wing drone relies on its long tilted wings to create a lift effect while cruising
  • Unlike multirotors, these UAVs do not need so much battery to stay aloft since the lift effect is passive
  • Classical fixed-wing drones require a catapult or hand-launch to take flight, and a parachute or a soft surface to land
  • Vertical take-off and landing (VTOL) fixed-wing drones are a hybrid of a fixed-wing and a multirotor, which can carry higher-end payloads and take-off and land from a wider range of surfaces 

Fixed-wing disadvantages (and a push for something more)

As word caught on about the advantages of fixed-wing drones, many companies began making the switch to save time in the field. But there were—and always will be—a few catches that end up consuming quite a bit of project time while limiting the quality of the results.

First, these systems require large, open and relatively soft landing areas. If a football or soccer field happens to be closeby, this reduces risk. But if not, searching for similar such areas on a mine, construction or forested site can be a time-sucking, if not fruitless, exercise. Add to this that if the area isn’t big enough, belly-landing UAVs have been known to crash into trees or obstacles when low-altitude winds gust or due to planning errors that cannot be remedied once landing has begun.

Second, when it does land within a wide-open, planned area, the fixed-wing goes through a controlled crash. Every time. The shock that this transmits through the drone, and its payload, shortens its life span. 

Third, because classical, hand-launched, belly-landing fixed-wing drones must be thrown in the air and must land as mentioned, they need to be lightweight. This means the payload cannot weigh it down, and higher-end payloads are heavy.

The most you will get out of fixed-wing mapping drones that don’t require a catapult or land with a parachute or air bag is a payload in the 20-25 MP range. This avails decent accuracy yet it is worth looking closely at how this factors into coverage and quality compared to a higher-quality payload in fixed-wing flight (discussed in the next section).

 

fixed-wing vs. VTOL illustration
All-in-all these disadvantages can mean downtime or repeat flights, both of which reduce the benefits of the system. Users have been willing to put up with this, however, since the benefits still outweighed other methods … until the VTOL came along.

How much does a fixed-wing drone cost in the age of VTOL?

  • The cost of a fixed-wing drone can range from 11,000 to 20,000 USD depending on the model and whether or not certain features are included/activated
  • The shelf cost, however, does not exist independent from the amount of money the drone will save the user as a method for gathering data
  • Price does not indicate the limitations that the drone presents in terms of the user’s ability to take on projects
fixed wing vtol drone Wingtraone
WingtraOne is a tailsitter vertical take-off and landing (VTOL) drone blending the control and precision of the multirotor take-off and landing with the coverage of a classical fixed-wing. This design allows for higher accuracy than fixed-wings since the payload weight and quality limits increase.

The changing conversation: from fixed-wing to VTOL

As early as 2013, hybrid VTOL technology was impressing researchers who saw it as the next step in commercial UAV solutions. By 2017 VTOL began to pick up traction on the market as a solution that offered users the coverage of a fixed-wing drone plus the controlled vertical take-off and landing of a multirotor. This signified two important breakthroughs:

First, operators no longer had to search for massive, soft areas to belly land. The VTOL fixed-wing can touch down in a smaller area, and some can even rise up and lower down around high tree stands. Second, the payload quality is no longer limited to 20 MP since the passive lift of fixed-wing flight can keep heavier cameras in the air longer. This means you can gather data at a much higher—even survey-grade—accuracy and better resolution.

Explore the difference in image quality and accuracy across sensors

Best possible GSD at 65 m (213 ft) altitude

WingtraOne + Sony RX1R II


GSD: 0.8 cm (0.3 in)/px
Real resolution: 0.9 cm (0.4 in)/px

eBee X + S.O.D.A.


GSD: 1.5 cm (0.6 in)/px
Real resolution: 1.8 cm (0.7 in)/px

eBee X + Aeria X


GSD: 1.4 cm (0.6 in)/px
Real resolution: 1.7 cm (0.7 in)/px

Same GSD—1.5 cm (0.6 in)/px

WingtraOne + Sony RX1R II


Altitude: 110 m (361 ft)
Real resolution: 1.5 cm (0.6 in)/px
Coverage: 190 ha (470 ac)

eBee X + S.O.D.A.


Altitude: 65 m (213 ft)
Real resolution: 1.8 cm (0.7 in)/px
Coverage: 115 ha (284 ac)

eBee X + Aeria X


Altitude: 65 m (213 ft)
Real resolution: 1.7 cm (0.7 in)/px
Coverage: 135 ha (334 ac)

Same Altitude—110 m (361 ft)

WingtraOne + Sony RX1R II


GSD: 1.5 cm (0.6 in)/px
Real resolution: 1.5 cm (0.6 in)/px
Coverage: 190 ha (470 ac)

eBee X + S.O.D.A.


GSD: 2.6 cm (1 in)/px
Real resolution: 2.8 cm (1.1 in)/px
Coverage: 200 ha (494 ac)

eBee X + Aeria X


GSD: 2.3 cm (0.9 in)/px
Real resolution: 2.7 cm (1 in)/px
Coverage: 220 ha (544 ac)

These image comparisons from our report comparing the eBeeX fixed-wing drone with the WingtraOne VTOL drone demonstrate the difference in image accuracy, quality as well as overall coverage based on the payloads each type of UAV is able to carry. Note: the real accuracy has been hand calculated from the Siemens stars.

Another advantage of higher-end cameras on a VTOL craft is the coverage. Since the resolution capabilities of a better payload are double, users can fly higher and cover more area per image at the same resolution. This enables drone data capture on projects of a much bigger size, even into the hundreds of square kilometers range.

Multicopter coverage - WingtraOne covers up to 14 times more area in 1 one flight

Multicopters
20 Megapixels


Coverage: 8 ha (20 ac)
GSD: 1.2 cm/px (0.5 in/px)
Altitude: 44 m (144 ft)

fixed wing coverage -- around 40 percent less than wingtraone in 1 flight

Other fixed-wing drones
20 Megapixels


Coverage: 64 ha (158 ac)
GSD: 1.2 cm/px (0.5 in/px)
Altitude: 57 m (187 ft)

wingtraone coverage - up to 14 times more area in 1 flight than phantom 4 rtk

WingtraOne VTOL RX1R II
42 Megapixels


Coverage: 107 ha (264 ac)
GSD: 1.2 cm/px (0.5 in/px)
Altitude: 93 m (305 ft)

At a GSD of 1.2 cm (0.5 in) the WingtraOne VTOL drone can cover 40 percent more than a fixed-wing and 70+ percent more than a multirotor.

Finding the best UAV for your needs

As you can see, the fixed-wing drone has gone through quite an evolution over the past five years, with hybrid capabilities that open up new options. When comparing costs and benefits, it’s important to both consider the applications you are working on now as well as applications you would like to approach in the future.

If you choose a classical fixed-wing drone, you will be limited to the kinds of applications you can work on because of the way it launches and lands and the restricted capabilities of the sensor. While it might be a bit less expensive, it very well could cost you more over the long run in terms of what projects you cannot take on, and because it is more likely to run up a bill in terms of repairs.

Specifically, the costs in cases of one crash or bad landing with a classical fixed-wing often include: travel fees and double the time to re-fly the mission, extra nights in hotels for remote projects as pilots wait for repairs or parts, and repair or replacement costs if not covered by insurance or warranties.

Calculate flight time and labor costs for your own project

Answer a few questions about your typical surveying project requirements, and you will receive a customized report per e-mail with coverage, time and labor cost estimates.

On the other hand, a VTOL drone can tackle large projects, offering consistent results in a dependable way with the added bonus of a higher level of safety. Specifically, operators maintain a distance from the aircraft at all times, since it can take off and land autonomously. Plus, unplanned movements in wind gusts—or worse, crashes—are minimized due to vertical lift-off and precise landings. 

Did you know? There are two main types of VTOL mapping drones. The tailsitter and the quadplane. Explore some key differences, advantages and disadvantages here.

In the end, VTOL means less hesitation around signing contracts to cover rugged or forested sites, and the image quality improves to the level of payloads boasting 42 MP and more. Add to this that the projects will take less time to complete due to better coverage with these grades of payloads, and you have saved as much as (or more than) you invested to upgrade to a fixed-wing technology that leads the market today.
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Wingtra develops, produces and commercializes high precision VTOL drones that collect survey-grade aerial data.
Wingtra
Wingtra

Wingtra develops, produces and commercializes high precision VTOL drones that collect survey-grade aerial data.

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