Body - A few years ago, drones were only a fancy toy and expensive collectables. The prototype was more plentiful than the main product. In recent years, drones have taken over the world. It has become affordable and serves many roles in the world today. In some countries, you can simply order a drone online and fly without even a license. Nevertheless, the transition of drones from a novelty to a household toy has been phenomenal and impressive. A closer look would reveal the factors that contributed immensely to this swift transition. The change in the design as well as the materials for making the drones largely contributed to this transition. Lets briefly delve into the history of drone making materials.
HISTORY OF CARBON FIBER COMPOSITES IN DRONES
As far back as 1916 during and shortly after World War I, drones (UAV) were already in use. One major setback it had was the heavyweight of the materials. Taking off was not smooth because of the heavyweight of the material. Speed was also limited due to this material weight issue. Phasing out woods in the body of aeroplanes was ongoing then. Improved technology brought the idea of using lightweight material for making the body and another part. Most regular aeroplanes are made from titanium, steel, and aluminium.
A new revolution came with the introduction of carbon fiber composites. The use of carbon fiber composites and carbon fiber sheets dates to 1963, it was mainly available for military use because of its high cost. The use of lightweight carbon fiber composites brought improved efficiencies in drones by increasing its acceleration and speed. Similar revolution also happened in Formula 1 racing cars in the 70s with the introduction of carbon fiber. Few decades down the line, all Formula 1 chassis are 100 percent carbon fiber. Similarly, today’s drones consist majorly of carbon fiber parts. Body parts such as the frame, rotor and even the blade are made of carbon fiber composites.
Head-to-head, carbon fiber composites offer more advantage than aluminium, titanium, and steel.
It has a lighter weight, which is a major concern in drones. The lighter the weight the better it flies. It equally has a high strength-to-weight ratio, and very high modulus elasticity-to-weight ratio also. Similarly, it offers good corrosion resistance. A closer examination of these criteria would further reveal the increase in the use of carbon fiber parts in drones.
Initially, in the early days of aeroplane making, prepreg composites
were used because of its useful mechanical properties. It boasts of strength since it combines several of fibre-reinforced plastics (FRP) with implantation of epoxy resins.
The invention of drones created the need for materials with super strength. Carbon fiber sheets and composites are extremely strong with amazing stiffness to weight ratio and strength to weight ratio. Typical carbon fiber for most top-grade drones have 60 percent more strength that aluminium of the same thickness. Additionally, its rigidity is about 31 percent more than that of aluminium of same the same thickness as well. Another measure of the strength of carbon fiber composites is the stiffness. You can determine the stiffness of a material by measuring its modulus of elasticity.
A aerospace two-direction carbon fiber – highest modulus material has a stiffness of 190 GPa compared to aluminium of the same thickness which has 69 GPa. This is more than twice the value of aluminium. Similarly, aerospace, one -direction carbon fiber – highest modulus has stiffness value of 380 GPa while aluminium has 69 GPa. In order words, carbon fiber composites stiffness is five times higher than aluminium of the same thickness. Since carbon fiber outperforms aluminium in a stiffness test, little wonder why the reason for choosing carbon fiber panels over the rest.
Extreme lightweight is one of the main attributes of carbon fiber parts. It weighs about five times less than steel and 1.5 times less that aluminium even though it is five times stronger in stiffness. This weight advantage contributes largely to the design of drones. The use of carbon fiber can drastically reduce the weight of drones by 20-40 percent compared to the aluminum.
Carbon fiber can come in very tiny strands like human hair. In carbon fiber parts manufacturing, these strands can be wound together to form various parts. In the case of drone parts, these very tiny strands are laid together in several quantities over a mould. Resin is added to make it solidify and take the shape of the mould. Engineers can make different shapes through this process. Carbon fiber moulding technology encourages the making of several intricate parts of drones.
Typically, the net weight of big drones made with carbon fiber parts weight between 5 to 50 kg. In aerospace, the lighter the aircraft, the easier it can take off and also the less energy it consumes. Swift and rapid take-off by elevation due to its lightweight are the key attributes of a drone. The use of carbon fiber parts in drones further contributes to its lightweight features.
NEGLIGIBLE THERMAL EXPANSION
Carbon fiber composites have almost zero thermal expansion. In other words, its coefficient of thermal expansion (CTE) is close to 0. In simple terms, carbon fiber parts will become dimension stable when subjected heat. Aluminium, titanium, and steel all will increase when subjected to heat and shrink when subjected to cold. The presence of the epoxy resin in carbon fiber composites drastically reduces its heat conductivity. In fact, the conductivity of carbon fiber composites with epoxy resin is 40 times less than aluminium and also 10 times less than steel. So, it will not be completely wrong to assume that carbon fiber is a good insulator. This low thermal expansion and high-temperature tolerance accounts to why most drone makers prefer carbon fiber
In summary, carbon fiber composites offer great benefit in drone making. Its malleability allows machining carbon fiber sheets into various shape relatively easy. The high percentage of carbon atoms in it gives it the advantage of high tensile strength, high stiffness, and low weight. It also has very good chemical resistance which prolongs its lifespan. Finally, carbon fiber composites are the future of drone makings as it is gradually phasing out the use of titanium, aluminium and steel.