Drones – are these material to the business?

Following along from Valour Consultancy’s last blog about niche market opportunities in the drone industry, we might look at the construction of drones to meet these niche needs.

When we think of vehicle construction, then there is a tendency to assume the manufacturer has chosen the best material for the job but manufacturers have to balance numerous considerations beside performance such as availability of supply, cost, and ease of manufacture. This is why most cars on the road are made of steel and not carbon-fibre (which race cars are made of.)

If we consider drones as a subset of airborne craft, we can look at the progress of the development of airplane manufacture which started from wood and fabric, then, during the Second World War, fighter planes were made from steel. With the advent of commercial airlines came the aluminium fuselages, the carbon fibre and composites. We shall disregard titanium frames (used by such luminaries as the S71-Blackbird) as a rather specialised application.

The production of modern drones, by and large, has started off with the benefit of all this aviation research to draw upon and the large UAV manufacturers opt for carbon fibre reinforced polymer bodies because this material combines the best performance for normal use combined with ease of manufacture, availability and price. In addition, it is already referred to in the existing standards for aircraft materials.

The American Society for Testing and Materials (ASTM) has a series of standards covering aerospace materials including carbon-fibre, aluminium alloy and military-grade polymer alloys. Care has to be taken with the use of some of these materials as they inhibit radio signals. Endurance during robust weather events and in low-altitude urban environments where wind shear and canyon funnelling can be problematic have required UAV developers to choose very strong materials and design the frame structure to accommodate some flex.

The simplest material for UAV construction is wood. No commercial UAV that has been investigated has a wooden frame but the North Korean military use wooden framed aircraft and UAVs to foil South Korean radar.

In general, some combination of carbon fibre, aluminium and/or G10 which is an epoxy laminate of fibreglass. Carbon fibre and aluminium for commercial UAVs are used sometimes but they have the problem of being opaque to RF signals which only becomes a problem when operating at a distance from the base station. The majority of UAVs are manufactured with frame struts of carbon-fibre-reinforced polymers (CFRP).

For specialist industrial UAVs that would dare to go where few have gone before – methane-filled mines, oil-well fires, sand storms, and extreme weather events – high wind, torrential rain, fog and freezing temperatures (think a summer day in Glasgow), then batch or bespoke manufacture is required. This is an entirely different business from mass production as 3DR have recently acknowledged.

Bespoke construction allows the use of materials for drone components more closely aligned with the requirements asked of them such a radio-frequency transparency, greater flexibility, imperviousness to corrosive or abrasive atmospheres or greater stability over large temperature ranges.

Many such materials are now available such as graphene (for use in reinforcing carbon fibre composites), basalt fibre reinforced composites and other ceramic-matrix composites (CMCs) which promise greater high-temperature resistance, greater resistance to deformation and greater resistance to abrasion. Scientists at the Karlsruhe Institute of Technology (KIT) have developed very strong bone-like structures that are lighter than water. At the moment they are only able to produce these millimetres thick but as the technology develops, be sure to expect their appearance in UAVs and aircraft.

It is not only the fuselage of the drone that can expect to be changed for specialised applications but also propellers, wiring (including the windings of the motor as super-conducting materials approach use at ambient temperatures), and integrated circuit boards which are rapidly approaching nano-scale size. Valour Consultancy will provide a further update report later this year, with further analysis and evaluation covering components, new materials and additional commercial UAV service revenues. For more information on our full report, click here.