Wright Brothers, the innovative brothers who created one of the best outbreaks in history, the first successful airplane. December 17, 1903 marked the date where Wilbur and Orville Wright changed history and the word aviation was born. After this remarkable discovery, airplanes are further utilised for ‘travel, commerce, war, and communication’ (Wright Brothers Impact, 2017). A century later, with numerous improvements and modification, the airplane is something that is taken for granted. Today, the world is contemplating different technologies, shapes and materials that would develop a better and more fuel-efficient aircraft.
Carbon dioxide (CO2) emission is the threatening disadvantage of an aircraft. Even though emissions from aircraft only consist of ‘2-3% of global CO2 pollution, it could jump up as much as 500% by 2050’ (Grose, 2013). However, by improving the aerodynamic and finding and utilising lightweight materials, the mass of the plane reduces which results in a more fuel-efficient aircraft. The modern aircraft is constructed using the material, aluminium, a strong, reliable and a light weight material. Steel and titanium are also used, however, due to the weight of the material it is less frequently used.
Even the smallest reduction in the drag of a commercial aircraft ‘can save up to 40,000 litres of fuel, thus reducing emissions by around 5000kg’ (Spampinato, 2015). Due to this, new materials are being tested and developed continuously to identify a light composite material that could cause this to be the reality. A composite material is formed when ‘two or more materials are combined together to create a superior and unique material’ (Johnson, 2017). When these different materials are incorporated within each other, they tend to strengthen the useful properties, and minimise their weaknesses. Composites are alternatives for metals as they are equally strong but much lighter; meaning they are the future materials demanded for the aerospace industry.
To today, Boeing 787 Dreamliner is the most fuel efficient commercial airplane, as its skin composes of more than 50% of carbon fibre instead of the usual aluminium alloys. The material, carbon fibre is one of the strongest and most lightweight material known upon the manufacturing world and in science. It is lightweight because it is a low-dense material with a very high strength to weight ratio as why carbon fibre is ultimately difficult to be stretched or bend as it has high tensile strength. Its chemical structure allows the material to have the property of low thermal expansion. Materials that are heated over a prolonged time can expand its size and the volume. Steel and aluminium have been known to contract while in flight, and by the alternative use of carbon fibre, it can reduce the time and money spent on maintenance and increase the safety of the passengers and the crew. It has exceptional durability; most materials tend to wear out after numerous use but the carbon fibre composites can cope the stress due to its unique structure.
Carbon fibre also can conduct electricity because it is composed 95% of carbon. Carbon itself cannot conduct electricity, however the process can occur in its ‘amorphous or graphite allotropes because of its electronic configuration,’ (Johnston, 2016). In the graphite allotrope, ‘each carbon atom is bonded into its layer with three strong covalent bonds’ (Bbc.co.uk, 2017). However, this allows each atom to have free electron, ‘which together form a delocalised ‘sea’ of electrons loosely bonding the layers together,’ (Bbc.co.uk, 2017), and these electrons can move together allowing the graphite allotrope to conduct electricity. There is also a major reason carbon fibre is being used for the fuselage of aircraft, its property of fire resistance. Unfortunately, many aircrafts that is manufactured using aluminium or steel has a high risk of being flammable which causes malfunction and in worst case scenario, crash. Due to this, the aeronautical industry has decided to utilise more carbon fibre material in their manufacturing process of the future aircrafts, as these properties have many advantages.
Carbon fibres are strands of carbon nanotubes which is a long chain of carbon. Carbon nanotubes, as seen in figure 2, ‘are composed of carbon atoms linked in a hexagonal shape’ (Understandingnano.com, 2017). These nanotubes are very strong and are capable of regaining its original shape when its either bend or external force is applied. Its extreme strength is due upon the interlocking and the circular shape of the chemical formula. These nanotubes can ‘naturally align themselves into ropes held together by Van der Walls forces,’ (Carbon Fibre, 2017). Van der Walls force is a term used to determine the attraction of intermolecular forces between molecules.
Carbon fibre is manufactured through polymerisation which is done through polyacrylonitrile (PAN) and this is base of the material. PAN is mixed with a catalyst because it increases the rate of a chemical reaction without it undergoing a permanent chemical change. Almost 90% of carbon fibres are assembled from PAN and rayon and petroleum pitch is the remaining 10%. All these raw materials are organic polymers
This material has a very negative environmental impact as it uses a great deal of energy to be produced. The manufacturing of carbon fibre includes both oxidation and carbonisation furnaces and these have been known to emit hydrogen cyanide, ammonia, and volatile organic compounds. The pollutants are very harmful to humans even in small quantities. It also contributes to greenhouse gases because it emits carbon monoxide and nitrogen oxide. However, as this material has great durability and low erosion rates, there would be less replacements and maintenance. Meaning there should be less produced because of its properties acting as a factor.
As it said above, nearly 5000kg of carbon dioxide emissions can be reduced by reducing the weight of an aircraft. This comes into the equation, as carbon fibre is now preferably used then steal due to its lightweight. There is an average of 102,465 flights per day, 37,400,000 flights per year, and if these aircrafts were manufactured containing carbon fibre, an exceptional amount of carbon dioxide emissions can be reduced. Carbon fibre can also be recycled to some circumstances; however, it is not easy neither cheap. However, the recycling process occur when the carbon fibre is cut into strips that are of one inch in length, and then it is melted, which can be used to transform it into a thermoplastic.