Smarter wings for bird-like flights
Taking inspiration from nature, an EU-funded project is developing smart airplane wings that can sense changes in pressure and adapt their shape instantaneously. These airplanes of the future will be more energy efficient and silent: more bird-like, in effect.
The EU-funded SMS project is installing next-generation fibre optic-based sensors that take pressure measurements in real time during flight, enabling wings to adapt to changing conditions in the sky. The adaptation will also help to reduce noise and vibration, increasing passenger comfort and safety, the project states.
Modifying wing shape to achieve maximum aerodynamic performance could help airline operators cut fuel costs and reduce emissions. By demonstrating these efficiencies in simulations of an Airbus A320 wing in flight, the project hopes to contribute towards a new era in wing design, capable of achieving at least a 1 % reduction in fuel consumption and around 0.5 % in CO2 emissions on its own.
The smart technology being pioneered by SMS could also open up new possibilities and applications in other sectors. Embedded electroactive sensory systems for example could be installed in wind turbines, cars and ship propellers.
One thing that makes the SMS project unique is the degree to which the sensory system being developed is linked to real-time activation, explains Marianna Braza, director of research at CNRS and the projects coordinator at the Institut National Polytechnique de Toulouse in France.
This is how birds of prey operate in flight. Their internal sensory systems capture pressure fluctuations, which are instantaneously analysed and used through their multiple-scale wings, ailerons and feathers system, to optimise aerodynamic performance in real time. This allows these birds to swoop down on prey silently and efficiently by increasing lift and decreasing drag. Adapting the shape and vibratory behaviour of a planes wings in real time has the same effect.
Fly like a bird
The fibre-optic sensors being pioneered by the three-year project, which began in May 2017, form part of a system known as hybrid electroactive morphing. Slight variations in pressure picked up by the sensors are transmitted to a deformable high-lift flap on the wing.
Changes in shape are achieved by shape memory alloys that are embedded within the lifting structure. These alloys remember their original shape, and when deformed can return to their pre-deformed shape.
This behaviour mimics the performance of bird feathers in flight, adds Braza. Of course, birds never fly at cruising speeds, so the SMS project is only partly bio-inspired.
Ready for lift-off
With more than two years to go, SMS still has development work to complete before trials can begin. Nonetheless the project team is confident that substantial increases in aerodynamic performance can be achieved drag reduction and lift increase during take-off and cruise speeds, as well as lift increase and noise reduction during landing.
We are setting up multi-disciplinary teams to study materials that can best improve aerodynamic efficiency, says Braza. It is worth noting that existing systems attempting drag reduction produce an increase in noise, and vice-versa. A key aim of the project is to increase aerodynamic performance while reducing noise at the same time.
SMS emphasises that existing systems to adapt wing shape during flight are based on hydro-mechanical actuators, which are heavy and slow to implement. The electroactive actuators being developed by the SMS team work instead capture vibrations and redistribute this energy in order to adapt wing shape. This embedded system promises to be lighter, more versatile and more economical.