In the 15th century Leonardo Da Vinci wrote of bats, kites, and birds as sources of inspiration for one of his most famous inventions, a machine with flapping wings powered by the human body. His drawings of a flying machine, or ornithopter, are seen by some as the beginning of the history of manned flight.
It took another four hundred years before the first heavier-than-air machine took flight under its own power, near the small town of Kittyhawk in North Carolina. The Wright brothers gave birth to aviation as we know it in 1903 and ever since engineers have been refining and improving the dynamics of flights to build bigger and more efficient aircraft.
And inspirations from the animal kingdom could help reduce aviation’s climate change impact.
In 2009, a team of doctoral students from the Aeronautics and Astronautics program at Stanford University conceptualised plans for commercial planes to save fuel by mimicking birds flying in formation.
The theory is that the plane behind the leading aircraft will in effect surf the wake vortex of the plane in front. According to a working paper presented by ICAO in 2019, the trailing aircraft could cut fuel burn as much as 10%.
Speaking just two months ago Airbus CEO Guillaume Faury confirmed his support for formation flight as a sustainability tool. In fact, Airbus continues to research the flight mechanics of a number of birds and has designed a model based in part on the wing design and movement of the albatross.
The AlbatrossONE project team built a small-scale remote-controlled aircraft with freely flapping wing-tips capable of reacting and flexing to gusts of wind to provide extra efficiency.
NASA has also been looking at nature. In recent years, it teamed up with the US Air Force Research Laboratory and FlexSys Inc to successfully complete initial flight tests of a new bendable “morphing” wing, that is closer to a bird’s wing than the hinged wings in use today.
According to NASA, it has the potential to significantly reduce fuel costs, reduce airframe weight, and decrease aircraft noise during take-offs and landings.
The technology, which can be retrofitted to existing aircraft wings or integrated into entirely new airframes, enables engineers to reduce wing structural weight and to aerodynamically tailor the wings to promote improved fuel economy and more efficient operations while also reducing environmental and noise impacts.
Birds and other winged creatures are an obvious start for biomimicry but they are not the only role models for aviation engineers.
Shark-based technology hit the headlines recently when Lufthansa and BASF unveiled a surface film that can be applied to a plane that mimics the structure of a shark’s skin.
Four hundred million years of evolution has produced a shark skin that has thousands of small scales, or denticles, in varying shapes and sizes around the body which reduce drag through the water.
Lufthansa Technik and BASF have developed a coating that contains tiny riblets to mimic the denticles. It can reduce drag up to 1% on a Boeing 777. The airline announced it would use the material on its B777 freighter fleet.
For the entire fleet of ten cargo aircraft, this translates to annual savings of around 3,700 tons of kerosene and just under 11,700 tons of CO2 emissions, which is the equivalent of 48 individual freight flights from Frankfurt to Shanghai.
Lufthansa Technik and BASF said they will continue to develop the technology to include additional aircraft types and even larger surfaces to help airlines meet greenhouse gas targets. Initial models show that the use of sharkskin technology could eventually reduce CO2 emissions as much as 3%.
Aviation is determined to cut emissions 50% relative to 2005 levels by 2050 and a growing number of individual airlines have pledged much greater cuts; zero emissions by 2050.
The biggest gamechangers are likely to be in the form of Sustainable Aviation Fuel, and electric and hydrogen powered engines.
But that doesn’t mean the drive for further efficiency will take a back seat. New fuels will still be a significant cost for airlines, which means engineers will continue to seek improvements in aircraft design, and one of the best places to start is looking at how nature tackled the problem.