What do velvet, the skin of a shark, and advancements in aircraft aerodynamics have in common?
The answer rests in a field of scientific study that involves examining what can be extracted, learned and duplicated from the natural world.
Known as ‘biomimicry,” or biologically inspired engineering, this is the study and imitation of nature’s best ideas to help solve human challenges. A growing number of aeronautical innovations have been inspired by an array of natural structures, organs and materials – and these tried and tested patterns of the natural world will continue to be a powerful source of inspiration in the future.
The lotus effect
The surface of a lotus leaf has evolved to keep it clean and dry by causing rainwater to roll off, taking any dirt with it. Known as the “lotus effect”, these properties have inspired coatings for cabin fittings, which shed water in beads and take contaminants with them. The process improves hygiene and reduces the amount of water needed, which reduces the weight of the aircraft and subsequently reduces the amount of fuel consumption and carbon emissions. This innovation is already in use on the surfaces of Airbus cabin lavatories and is expected to be found on the fabric of seats and carpets in the future.
Moveable wing surfaces
Sea birds have the ability to sense gust loads in the air with their beaks and react by adjusting the shape of their wing feathers to suppress lift. The nose of the new Airbus A350 XWB contains probes which can detect gusts and deploy moveable wing surfaces for more efficient flight. This helps reduce fuel consumption and emissions.
Eagle inspired winglets
If the wings of large birds like the Steppe Eagle were too long, their turning circle would be too big to fit inside the rising columns of warm air which they use to soar. The eagle’s wings perfectly balance maximum lift with minimum length by curling feathers up at the tips until they are almost vertical. This provides a barrier against the vortex for highly efficient flight. If built to a conventional design, the A380’s wingspan would have been three metres too long for the world’s airports. But thanks to small devices known as ‘winglets,’ which mimic the upward curl of the eagle’s feathers, the A380’s wings are in compliance with airport limits by 20 cm. but still provide enough lift for the world’s largest passenger aircraft to fly efficiently – saving fuel, lowering emissions and reducing airport congestion.
The silent flight of the owl
Over a period of 20 million years, owls have evolved to have serrated feathers on their wings and downy feathers on their legs, which minimise aerodynamic noise. Even though modern aircraft already produce 75 per cent less noise than those built 40 years ago, Airbus engineers are studying owls to further unlock the secrets of silent flight. Ideas include a retractable brush fringe to mimic the owls’ trailing feathers and a velvet-like coating on aircraft landing gear.
The use of bionics
In the biological world many creatures, such as bees and butterflies, use lightweight, active skeletal structures for a variety of purposes. These examples have inspired Airbus to consider the use of such “bionic structures” as part of future aircraft structures. If the aerodynamic surfaces could be made lighter or more adaptive to the local environment, the weight of the aircraft could be reduced, which would result in reduced emissions. Airbus engineers are also exploring nature-inspired manufacturing techniques to create “bionic bones”, which may enable such lightweight active structures on the aircraft of tomorrow.
‘Groovy’ shark skin
A shark’s skin is covered by microscopic grooves that scientists have found actually reduce their drag through the water, allowing the shark to conserve energy as it searches for food. For over 30 years this “groovy skin” concept, or riblet as it is referred to in the industry, has been investigated and tested by aerospace engineers and eventually will be adapted and applied to the construction of Airbus aircraft. Just as a shark can minimise the energy it expends in motion, these microscopic grooves can help to reduce the fuel consumed by a jet aircraft.
Butterflies and insects are some of the most beautiful and delicate creatures on the planet, which belies the fantastically intricate mechanisms in their wing structure, designed to achieve optimum efficiency in flight. Soft membrane and blood vessels (micro-capillaries) can stiffen or relax to allow the wing to adapt to every stage of flight. Airbus engineers have similarly developed aircraft wings that naturally turn and twist in flight, but if this could be controlled, then their efficiency could be enhanced, reducing the fuel consumed during flight. Engineers are researching the possibility of using small movable surfaces and active internal structural components as part of an aircraft wing to mimic the way micro-capillaries in a butterfly’s wing, making for more efficient flight in the future.
In nature, large birds sometimes fly together to save energy and travel further. When flying in formation – as seen with migrating geese or ducks – the leading bird’s wings generate whirling masses of air. The following birds benefit from this air current to obtain extra lift, meaning it needs to use less energy to fly. Aircraft wings create the same effect, known as a trailing vortex. Military pilots often use the same formation flying techniques to reduce the amount of energy – fuel burn – that the aircraft use. At the moment, passenger jetliners do not use this technique because of safety concerns. However, Airbus is working with some of its partners to explore the idea as a way to reduce both fuel consumption and emissions on long distance flights.
Airbus would like to thank the team at Wildscreen’s ARKive project for the butterfly image representing biomimicry.