Materials ScienceTechnology

Graphene in Aircrafts

The world is soon entering a new era of technology pushed forward by the engineering of graphene. This new material consists of carbon atoms held together in a honeycomb structure. Graphene has caught the attention of many scientists and engineers globally. Researchers have been trying to understand this material and its applications since 2004 when professors at the University of Manchester extracted one layer of graphene from graphite[1]. Ever since then, the enormous volume of research conducted on graphene has led to a vast array of ideas and innovations being developed in numerous sectors including the aviation industry.

Properties of graphene

Image result for graphene structure

Figure 1: Layer of Carbon atoms in graphene

Graphene is one atomic layer of graphite, consisting of carbon atoms where each atom is covalently bonded to three other atoms in a honeycomb lattice. Graphene has a superior structure to graphite. This is because graphite is made of multiple layers of graphene which are bonded to each other through London Dispersion forces as the p-orbitals, the area around an atom where electrons are most likely to be situated, of carbon atoms in a layer are close to those of another layer, the electrons in those orbitals to be delocalised and can flow between the layers.

Although layers themselves contain strong covalent bonds within them, the interlayer London forces are weaker in comparison and so they provide a structural weak point in the material. This fault is not present in graphene’s structure [2].

Graphene is also incredibly conductive of electricity. Its current density (how much current flows through a unit area) is 1 million times greater than copper and its intrinsic mobility (a measure of how quickly an electron can move through a material) is 1 thousand times greater than silicon[3]. Each carbon atom in graphene has four electrons in its outer shell, three of which are used for bonding. The fourth electron, however, is free to move along the layer of graphene to flow as a current, with little resistance to the electron’s path [4].

Ultra-lightweight planes

A basic principle of flight mechanics is that the weight of a plane determines how much fuel is consumed to generate enough lift to elevate it off the ground and hence allow it to reach higher altitudes. This is because the lift force counteracts the weight of the plane; when greater than the force of weight, lift will cause the plane to soar upwards.

Image result for plane lift and weight diagram

Figure 2: Forces on an aircraft during flight

The lift is caused by the interactions between the wings and the streamlines of air flowing past the wings when the plane is moving forward at a sufficient velocity, which in turn is achieved by the forward thrust produced by the fuel [5].

If graphene was to be the material used to construct key parts of a plane, such as being integrated into the wings, the overall weight of the plane would be much lower than if it were made of other materials (such as aluminium). This is because graphene is much stronger and lighter than aluminium; therefore less is required to achieve the same strength ratings [6].

Significantly less weight carried by a plane subsequently leads to less fuel required which is a vital advantage in comparison to other designs. Namely:

  • Money can be saved on journeys as less fuel will be required to produce lift for the duration of flight.
  • More distance is covered per unit of fuel which means that a graphene-enhanced plane can fly for longer with a certain amount of fuel compared to other designs.
  • Less fuel consumption means that less emissions will be produced, increasing the sustainability of the aviation industry.

Moving forward with electric planes

Advancements in electrical engineering and their applications in the automotive industry has led to an increasing number of cars becoming electric. This new concept of electric transportation may finally apply to the aviation industry.

Image result for electric planes batteries

Figure 3: Electric Plane

The innovation of electric planes comes with certain benefits such as decreased pollution and more comfortable flights [7].

However, the industry will have to wait for this dream to come to reality, as, currently, there exist multiple fundamental design issues in electric planes. A completely battery powered aircraft will require enormous amounts of electricity, and the batteries required to contain this much energy are much too heavy. Incorporating heavy batteries into a design can significantly increase the overall weight of the plane which then requires more heavy batteries to produce sufficient lift; thus an efficient design cannot be achieved [8].

Figure 4: Extra’s electric aerobatic 330 with Siemens’ developing electric motor technology

The fact that heavy aircrafts have high power requirements and batteries themselves being heavy creates a cycle of the plane’s design getting heavier and heavier, posing an overwhelming obstacle for engineers to overcome.

This is where graphene steps in to solve the issue. As mentioned, utilisation of graphene in aircraft design could minimise the weight of the plane, thus decreasing the amount of energy required to stay airborne. This will require smaller batteries which could open doors to new designs of electric planes. The concept of efficient electric planes becomes a more feasible reality when engineers consider integrating the use of graphene into the actual batteries.

Additionally, batteries contain coatings of carbon (often on the electrodes) to provide conductivity. This coating of carbon can be in the form of graphene of which less is required to provide the same level of conductivity as conventional coatings.

These graphene batteries have a multitude of advantages:

  • Lighter
  • Higher capacity of storage
  • Shorter charging times [9]

Lighter batteries further reduce the weight. Higher energy capacity in batteries is also a huge benefit in the aviation industry as it means that batteries can store enough electricity to sustain lift for relatively long flights which would otherwise use expensive fuel and expend significant levels of pollution.

Wings

Carbon-fibre can be used in wings when it is woven into another material, usually plastic. This technique can be further enhanced by using graphene as the medium rather than plastic. Graphene is a lighter and stronger alternative to plastic which is conventionally used to hold together the carbon-fibre.

The University of Manchester built an aircraft with a graphene-skinned wing rather than the conventional carbon fibre wings; the flight tests showed that the new graphene-incorporating design had 60% more impact resistance[11]. There has also been recent development of Juno, developed by the University of Central Lancashire. Juno is skinned in a graphene-enhanced pre-impregnated material which could potentially be used on the fuselage (the main body of the plane) and wings of large-scale planes[12].

The Future

Image result for graphene wings

Figure 5: Prospero, the world’s first model plane to use a graphene skinned wing

Graphene is slowly becoming increasingly commercialised as engineers and researchers are getting over the problem of mass production. It is already being used in “bioengineering, composite materials, energy technology and nanotechnology”[13]. This means that it is very likely that this fascinating material may be used in newly developing aircrafts.

The world is entering a new era of aerospace technology and moving on from an age of reliance on aluminium. In an interview on BBC World News, Professor Andre Geim from Manchester University said “It’s really so surprisingly rich and this is because we get this new world of materials which we were not aware (of) before”. Due to the difficulty of graphene mass-production, the substance will probably be used to enhance aircrafts rather than to construct them. However, these enhancements can have major impacts on the performance of flying machines and may help industrial leaders address the rising concerns for the environmental impacts of flight as the world faces a growing climate emergency.

References

  1. “Discovery of Graphene,” University of Manchester. [Accessed 18 Nov 2019]. https://www.graphene.manchester.ac.uk/learn/discovery-of-graphene/
  2. Amaia Zurutuza, “Graphene & Graphite – How Do They Compare?,” Graphenea, accessed March 21 2020, https://www.graphenea.com/pages/graphene-graphite#.XnZTm4j7SUk
  3. “Graphene: the gold rush that is going to change the world… but when?” Investorintel, August 26, 2013, https://investorintel.com/sectors/technology-metals/technology-metals- intel/graphene-the-wonder-material-that-is-going-to-change-the-world-but-when/
  4. Cliff Curtis, Jason Murgatroyd and Dave Scott, Edexcel AS/A level Chemistry 1, (London: Pearson Education Limited, 2015), 2.
  5. David F. Anderson and Scott Eberhardt. Understanding Flight, (United States of America: McGraw-Hill, 2010), 2.
  6. “Graphene,” Explain That Stuff, last modified December 1, 2018, https://www.explainthatstuff.com/graphene.html
  7. Tom Metcalfe, “Electric planes promise big benefits for air passengers and the planet,” NBC News, April 4, 2018, https://www.nbcnews.com/mach/science/electric-planes-promise-big-benefits-air-passengers-planet-ncna862001
  8. Andrew J. Hawkins, “Electric flight is coming, but the batteries aren’t ready,” The Verge, August 14, 2018, https://www.theverge.com/2018/8/14/17686706/electric-airplane-flying-car-battery-weight-green-energy-travel
  9. “Graphene batteries: Introduction and Market News,” Graphene-info. Last modified January 24, 2019, https://www.graphene-info.com/graphene-batteries
  10. “Graphene aerospace strategy launched,” The University of Manchester, March 13, 2018, https://www.manchester.ac.uk/discover/news/graphene-aerospace-strategy-launched/
  11. Yakub Qureshi, “Scientists eye first-ever aeroplane made using ultra-thin graphene,” Manchester Evening News, July 12, 2016, https://www.manchestereveningnews.co.uk/news/greater-manchester-news/scientists-graphene-aeroplane-university-lancashire-11602615
  12. “Haydale Supplies Graphene From World’s First Graphene Skinned Plane,” Composites UK, August 12, 2018, https://compositesuk.co.uk/communication/news/haydale-supplies-graphene-world%E2%80%99s-first-graphene-skinned-plane
  13. Jesus de la Fuente, “The Applications of, and uses for Graphene,” Graphenea, Accessed 18 Nov 2019, https://www.graphenea.com/pages/graphene-uses-applications#.XCU_jFX7TIU
  14. Andre Geim, “Graphene Revolution,” interview by David Shukman,Impact with Mishal Hussain, BBC World News, January 15 2013, www.youtube.com/watch?v=sugmA-pll4k.

Figure References

Title image. Source URL: https://netcomposites.com/news/haydale-supplies-graphene-for-juno-uav/ [Accessed 18 Nov. 2019]

Figure 1. Source URL: http://www.understandingnano.com/graphene%20sheet.jpg [Accessed 20 Mar 2019]

Figure 2. Source URL: https://i0.wp.com/ateworks.net/wp-content/uploads/2017/06/how-paper-plane-works.png?ssl=1 [Accessed 27 Dec. 2018]

Figure 3. Source URL: https://cdn.theatlantic.com/assets/media/img/sponsored/2014/11/Flight_final_master/resp-feature.jpg?1415737253 [Accessed 27 Dec. 2018]

Figure 4. Source URL: https://www.flyer.co.uk/wp-content/uploads/2016/04/Extra-Electric-Aircraft-330LE-1000×666.jpg [Accessed 18 Nov. 2019]

Figure 5. Source URL: https://scx1.b-cdn.net/csz/news/800/2016/flyingstartf.jpg [Accessed 27 Dec. 2018]

About the Author

Ahamad is an Aerospace student at the University of Southampton who has a keen interest in human-engineered flight. He has worked on industry projects with BRE and Airbus and would like to lead engineering research in the future. He is currently a part of the RAeS Solet branch student committee and is working to develop a strong engineering academic community at his university.

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