POB Column: Drone Airframes for Surveyors
Point of Beginning magazine asked Aerotas co-founders Daniel Katz and Logan Campbell to analyze the various components of drone technology that go into an effective drone survey program. They evaluated three key technologies across three articles: drone airframes, sensors, and georeferencing options. In each article they take an independent and analytical approach to evaluate which drone technology option is best for land surveyors. The first article focuses on drone airframes.
It is essential to remember that the drone is just one piece of an effective complete drone survey program. Ultimately what is even more important than picking the right drone is having Standard Operating Procedures in place that ensure data collection is consistent and repeatable, and having an efficient workflow for getting final linework from drone survey projects.
There are three general types of drone airframes for surveyors: small multi-rotors, large multi-rotors, and fixed-wings. Each has its relative merits and drawbacks, and each can be the right choice for certain types of surveyors and certain types of survey projects. The type that we often find there is most misunderstand about is fixed-wing airframes. This is because fixed-wings face the most unique restrictions due to regulations and physics.
Read below an excerpt from our article, focused on fixed-wing aircraft, and a table summarizing the trade-offs of all three aiframe types. To read the full article, visit Point of Beginning's website. If you are ready to start an industry-best drone surveying program, contact us.
Fixed-wing drones are typically about 3 feet in wingspan and can often be very light due to being constructed out of dense foam.
The primary benefit of fixed-wing airframes is their range. They are inherently much more efficient fliers than multi-rotors, and can fly for a longer time before requiring a battery change. For projects larger than 50 acres requiring good accuracy, this benefit can be substantial, as using a multi-rotor would often require so many battery swaps that they become inefficient.
Unfortunately, this benefit is usually negated by regulations. Today, it is required that a drone pilot actively watches the drone the entire time it’s flying. This is essential to avoid situations like emergency aircraft flying through. In most situations, operators will not be able to maintain line of sight for 50 acres, meaning they can’t take advantage of the entire range benefit of fixed-wing airframes.
In addition to this, fixed-wing aircraft have a handful of substantial drawbacks. The requirements to program take-off and landing patterns means that using the drone on projects is fairly complex. In addition, they tend to have short lifespans because they belly-land. They don’t have landing gear like an airplane, and instead just slide on their belly, which means they can quickly wear down.
Unlike multi-rotors, fixed-wing airframes must maintain a minimum speed to stay aloft. This means they have to fly high to minimize motion blur. And whereas most multi-rotors carry their sensor on a gimbal, which allows the camera to remain pointed straight down even as the drone turns or fights the wind, fixed-wings usually cannot carry a gimbal, which causes a higher frequency of unusable data due to blur or off-centered photos. Finally, fixed-wing airframes are quite expensive – usually twice the price of large multi-rotors with the sensor and support gear required.
For firms that regularly do very large survey projects of hundreds of acres or more and are rather proficient with drone operations, a fixed-wing aircraft may be the right choice. Working to get special waivers from the Federal Aviation Administration or using visual observers to effectively extend range of sight can help mitigate the line of sight limitations.