The birth of Hairplanes

The birth of Hairplanes

Alan Peaford reports on a new research project that could change the whole face of aviation – or at least its hair.

The birth of Hairplanes

When Orville and Wilbur Wright took to the sky with the world’s first heavier than air powered aircraft there were many that thought them mad, especially when they found the Wright Flyer was built out of wood from the Sitka Spruce, the largest of all the spruce trees in North America.

Bamboo became popular because of weight saving and this wooden era lasted until the 1930s at which point thin sheet metal began taking over as the prime aerospace material.

Airframes lagged behind propulsion when it came to disruptive technology and innovation and took the more recent strict environmental legislation and advent of the composite era to induce further leaps in structural design.

Hair-like sensors

And now, a new five-year research project to develop tiny hair-like sensors for use on the surface of aircraft is set to improve the control and sustainability of future aviation by taking us back to nature.

The project is supported by the Royal Academy of Engineering and BAE Systems, and sets out to develop an aerodynamic ‘skin’ that can be evaluated for use on future aircraft.

The research is led by Professor Christoph Bruecker, who recently became the Research Chair in Nature-Inspired Sensing and Flow Control for Sustainable Transport at City University, London.

The research will bring together hundreds of tiny transparent ‘micro-pillars’ with optical fibres on an aerodynamic surface, providing a way to measure airflow around the surface with much more detail and precision than the relatively few sensors currently found on aircraft.

By using an elastic material for the hair-like micro-pillars, the sensors can also flex in response to the airflow, allowing them to be used not just as passive sensors but for flight control, adapting to changing external conditions and providing finer control of an aircraft.

Using optical fibre technology also means that, unlike current sensors, the micro-pillars would not generate electromagnetic waves, allowing them to keep control even in harsh environments.

Inspired by nature

The new development has its basis in nature.

Professor Bruecker said: “The aim is not to copy nature, but to be inspired by it. By understanding the physical principles underlying natural flight, such as the structure of feathers and hairs, we can learn to improve our own systems. The detailed information provided by hair-like structures gives a much better understanding of a local flow situation, which the structures can then modify to improve aerodynamic control.”

Applications for the smart skin technology could extend beyond aircraft. As the micro-pillars can adapt to changing conditions they not only change the aerodynamic properties of a surface – for example, by reducing drag – but also its acoustic signature, so they could be used on wind turbine blades and other propeller systems.

Such detailed flow measurement and control could also be useful inside pipelines or on marine hydrofoils.

“I’m grateful for the support of the Royal Academy of Engineering and BAE Systems, whose collaboration means that the skin can be tested for real future concepts in aviation and marine transport,” Bruecker said.

Technological benefits

The project has excited the team at BAE Systems.

We believe that bio-inspired research will continue to provide important technological benefits for military and civil aircraft,” said Maureen McCue, head of research and technology at the company’s military aircraft business.

The project is a good example of how companies like BAE Systems can collaborate with universities to develop new, practical, technologies.

The support of the Royal Academy of Engineering also points to the potential of the concept.

Professor Sir James McDonald, chair of the Academy’s research committee, said: “Inspired by nature, Professor Bruecker’s research will engineer solutions to sensing and control in a whole new way, which could significantly improve the fuel efficiency and sustainability of aircraft – a major benefit to both the industry and to society.

“This exciting work should impact positively on sectors including aerospace, energy and bulk fluid transfer,” he said.

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