‘Drone’ is now a buzzword in the tech world. We read every day about new uses, across a steadily growing range of industries. And as players start the battle to claim their piece of the ‘early adopter’ drone pie, it’s important to understand that not all drones are created equal.
To be more precise, ‘drone’ is a generic term, perhaps like ‘personal computer’. All drones are vehicles to position payloads in places that are difficult, dangerous, or expensive for humans to access. Payloads can be anything, including cameras, sensors (electromagnetic beyond the visual spectrum, acoustic, seismic), care packages, signalling equipment, scanning devices… The list is varied and growing.
It is growing partly because of the ingenuity of specialists in different industries considering remotely piloted vehicles to do jobs in new ways. It is also partly because key technologies are becoming more powerful and economical, whilst also becoming smaller and more nimble.
Major investment and advancement has been made in drone technology to bring drones to our front door; to make drones smaller, lighter, and more suited to everyday needs. This effort has benefited enormously from advances in consumer electronics, energy storage, and precisely modulated wireless communication.
It is worth considering that compact processors and sensors, very small digital cameras, and efficient batteries, have all benefited greatly from the ubiquity of mobile phones. A simple comparison is to think how protruding aerials have disappeared, and how your phone knows whether you are holding it in portrait or landscape orientation via tiny solid-state sensors. The app ecosystem has also made vast resources and a reliable skill set available for software development.
Today, compact payloads can be flown economically and reliably, largely as a result of ‘convenience technology’ – enormous economies in electronics and energy storage.
Understanding the background ecosystem lets us see why most people think of a small multirotor when they hear the word ‘drone’. The low-hanging fruit has been a machine that takes off vertically, can hover near a target, and then land at the starting point laden with valuable data.
At the other extreme, people may think of large mysterious glider-like military machines that circle over combat zones gathering grainy images of suspect enemies and possibly delivering ammunition or guiding missiles to a target.
The space in between – commercial fixed-wing drones – is wide and ripe for development. It is where investment should and will be directed in the near future. The reason is inescapable physics: Multirotors (quadcopters, hexacopters and the like), are suited to short duration flights in relatively still air. They excel where short periods of hovering are required and frequent landings for new batteries are not a hindrance to the mission. A great example is ‘vertical missions’ to inspect towers, smokestacks, bridge pylons.
However, more and more applications call for long endurance – flying continuously over long distances, whether point-to point, loitering, or covering a grid for search and rescue or mapping purposes.
Fixed-wing drones expend less energy for a given mass to achieve the same range. Therefore they can fly further and longer on the same battery, hence the prevalence of fixed-wing for military reconnaissance.
The limiting factor today is the efficiency of the airframe. This has two major components: aerodynamic drag and structural weight. The two are somewhat interlinked because using stronger lighter materials can enable thinner structural members, reducing aerodynamic drag. A proper understanding of aerodynamic behaviour of loaded structures is necessary to know how to optimise performance.
Launching and retrieving must also be considered. Fixed-wing craft require a minimum airspeed to generate the lift they ned to fly. This minimum airspeed can be achieved by rolling down a runway, being accelerated by a catapult (including being thrown by a person in the case of smaller craft), or hitching a ride on another aircraft. Retrieval is also tricky and often involves bulky equipment such as arrestor nets or parachutes.
Combining the efficiency and range of fixed-wing aircraft with the practicality of vertical take-off and landing (VTOL) is the ideal, and a goal worth pursuing. Since VTOL requires additional components (whether tilt mechanisms or dedicated motors), it places even more importance on keeping the structure light. Every gram saved in the aero structure can be re-invested in the VTOL system without net penalty.
At Carbonix we specialise in aeroelastic structures, using advanced composite materials to create streamlined, efficient airframes, with a view to achieving unprecedented range, reliably.
A fixed-wing drone is usually composed of a unitary streamlined structure designed to travel longer distances with specifically designed aerodynamics. This makes them suitable for missions such as aerial surveying where a large area must be covered.
A recent study by Grand View Research predicts the drone industry will reach an estimated $2.07 billion by 2022. The main benefactors of the drone industry will be agriculture, energy and government industries – and more importantly – these industries have much greater need for the mission profiles of fixed-wing drones.
Image source: James, Sherry. (2015) ‘Latest Report: Commercial Drone Market Worth $2.07 Billion By 2022https://goo.gl/1Y9CWP, Grand View Research.
Advancements in fixed-wing drone technology are about creating lighter structures that can carry greater weight for extended periods of time, with a focus on reliability and the ability to withstand adverse weather conditions. Major investments are occurring and will be growing rapidly.
As airframes scale, low-tech materials stop being suitable and structural weight becomes a serious limiting factor. Carbon fibre and related advanced composites are increasingly being used to create fixed-wing drones.
Efficient structures also open the door to vertical take-off and landing (VTOL), increasing the versatility of fixed wing airframes.
At Carbonix our heritage in competition and our leadership in aeroelastic optimisation enable us to lead the way in making efficient airframes accessible to extend range economically.
So, as we all scramble to align our inner geek with the commercial realities of determining how and where to invest money in drone technology and testing, executives must understand how drones can truly help their bottom line, and which type of drone will ultimately achieve the best result for their business.
