The evolution of Eco-friendly aircraft
Ever since the airline industry started booming in the late 20th century, aircraft manufacturers and their engineers have been constantly and iteratively improving the fuel efficiency of their aircraft. Especially after the oil crisis in the 1970s caused by a disruption in oil supplies from the Yom-Kippur War and the Iranian Revolution of 1979.
The nations who relied on the region’s energy exports such as Australia, Canada, New Zealand, the U.S, Japan and western Europe suffered large shortages in petroleum supplies and in turn high prices. This event paved the way for high capacity fuel efficient aircraft such as the Boeing 747 and crippled the newly blossoming supersonic industry in the Concord. Being forced to create more fuel-efficient aircraft, manufacturers had to find innovative ways to improve the carbon footprint of aircraft.
Aircraft manufacturers frequently outsourced their engines from experienced companies such as Rolls Royce. Initially large airlines utilized turbo jet engines which consisted of an air inlet, compressor, combustion chamber and a turbine which propelled the aircraft of the time with loud jets of hot air rapidly escaping the exhaust nozzle. As turbo fan engines began to be refined to the point of feasibility, aircraft began adopting the more fuel efficient low-bypass turbofans of that era.
These engines were essentially the same as the turbo jet but they had a large ducted fan that fell before the compressors which provided most of the thrust. The bypass ratio of a turbofan is the ratio of the mass flow rate of the “bypass stream” (Flow of air around the compressor, combustion chamber and turbine) to the mass flow rate entering “the core” (compressor, combustion chamber and a turbine). The higher the bypass ratio and the internal temperature of the combustion chamber and turbine, the more thrust can be produced by the engines.
Engineers have been continually increasing the bypass ratio and the maximum internal temperature of the core in order to increase thrust and fuel efficiency. Some innovations such as the chevrons on the engine nacelles of some Boeing aircraft reduce sound levels but also reduce thrust, this shows exactly how engineering is a tug of war battle with physics.
Airline manufacturers have been copying nature for efficient air foils (the cross section of a wing that produces a pressure difference on either side which results in lift or downforce).
The wingtips of aircraft have had a larger emphasis on the fuel efficiency and stability recently. On the tips of wings there are areas of “bleeding” where the high-pressure air beneath the wing is able to flow around the outside of the wing to the low-pressure air above creating vortices (spirals of air) which increased drag and diminished lift at the tip of the wing. Wing tips acted as barriers to prevent the air from reaching the top of the wing or to shift the vortices away from the wing.
Newer more complex wingtips are being tested and fitted to existing aircraft and new aircraft which also help increase lift and in turn increase fuel efficiency.
Possible aircraft innovation
Obvious improvements like solar panels incorporated to aircraft are being considered, however there are multiple areas of improvement such as the use of electric engines but there are no batteries with a high enough capacity right now but there will always be improvements made by the genius engineers behind each aircraft.
Article by David Ogolo
School: St Georges Sixth Form, Harpenden, England