From shark skin to aeroplane wings: exploring quieter, more efficient aircraft

While the aviation industry has achieved remarkable improvements in fuel efficiency, noise pollution remains a persistent problem, particularly for communities located near airports. Long-term exposure to aircraft noise can affect sleep, increase stress levels and reduce overall wellbeing. It has also been linked to more serious health effects such as cardiovascular disease. On a personal level, I also wanted a project that would challenge me academically and take me out of my comfort zone by developing my understanding of aerodynamics, an area I had not previously specialised in.  

Taking inspiration from shark skin

I was drawn to nature-inspired design, also known as biomimicry, because it offers simple but effective engineering solutions based on millions of years of natural evolution. Nature often solves complex problems with efficiency and minimal energy use, and I was interested in investigating how these ideas could be applied to aviation. 

I decided to explore whether riblets, small grooves modelled on the texture of shark skin, could help reduce aerodynamic noise by altering airflow over aircraft wings. Sharks are exceptional swimmers, partly because their skin is covered with microscopic ridges that guide and regulate the flow of water. Engineers have previously discovered that these riblets can lower drag in aquatic environments, which raised the question: could the same concept improve airflow over aircraft surfaces? Although previous studies demonstrated riblets’ ability to reduce drag – the resistance faced by a body moving through air – I wanted to investigate whether they could also diminish the aerodynamic noise generated as air passes over structures such as wings or landing gear.

For consistency and clarity in my experiments, I selected the NACA 0012 airfoil. An airfoil is a small-scale model of a wing cross-section used in aerodynamic testing to understand how airflow behaves around aircraft surfaces. The NACA 0012 is a simple symmetrical airfoil shape that is widely used in aerodynamic research and wind tunnel testing rather than on full-sized aircraft, because its airflow behaviour is well documented and easy to compare across studies. The testing involved three variations: a smooth baseline model without riblets, a model with riblets applied at a shallow 5° angle, and another with riblets applied at a steeper 10° angle.

I carried out the testing in an anechoic wind tunnel, a specialised facility designed to eliminate sound reflections so that microphones capture only the noise produced by the test model itself. Alongside acoustic measurements, I used a hot-wire probe, a fine, heated wire that detects changes in airflow speed and turbulence. As turbulence, the chaotic and swirling motion of air, is a primary contributor to aerodynamic noise, monitoring its behaviour was essential.

Learnings from the wind tunnel

I discovered that riblets can influence noise levels, but their effectiveness depends significantly on their position. At 5°, riblets reduced turbulence in certain regions of the airflow, which in turn lowered noise levels at specific frequencies. Conversely, the 10° riblets performed less well and, in some cases, increased turbulence. This showed that riblets are not universally beneficial so, if used in future, they would have to be designed and applied carefully. In real life, this could mean adding riblets to aircraft as thin surface films or coatings on parts like the wings or landing gear. Even so, I was happy to see the improvements, although they were modest. In aerospace engineering, incremental gains can have substantial impacts when applied across entire fleets of aircraft.

Beyond the technical outcomes, the project was an invaluable learning experience for me. Working with advanced equipment in the wind tunnel gave me practical skills that extended far beyond the classroom. I learned how to set up experiments, collect reliable data and analyse it using MATLAB, a widely adopted engineering software for data processing and visualisation. Experimentation can be unpredictable: sensor irregularities and the need to repeat tests to confirm accuracy challenged me to adapt, which reinforced that persistence and critical problem-solving are essential engineering skills.

One of the most interesting findings was the strong link between noise reduction and efficiency. By minimising turbulence, riblets not only lower noise levels but can also reduce drag, which can lower fuel consumption. This highlighted that achieving sustainability in aviation often requires addressing multiple issues simultaneously.

Aircraft noise is more than a technical concern; it has social and environmental implications. It can disrupt the lives of people living near airports and impose restrictions on airport operations, such as night-time flight limitations. Being able to reduce noise not only improves quality of life but also supports sustainable growth in aviation. Riblets are particularly appealing here because they represent a passive solution: once applied, they work continuously without the need for additional energy or moving parts, unlike more complex noise-control systems. However, like any surface treatment, riblets would need occasional maintenance because dirt, ice or surface wear could reduce their effectiveness over time, especially during long-term aircraft operation.  

What's the future for riblets?

Looking ahead, future research could test riblets of different shapes, perhaps leveraging 3D printing to achieve more precise or complex shapes. Riblets could also be integrated with other noise-reduction technologies, such as serrated trailing edges, which are already known to reduce noise at wing tips. Although this project answered the initial research question, it also opened up possibilities for further investigation. At this stage, I do not plan to continue this specific project immediately, as my current focus is on my master’s studies and group research project. However, I would welcome the opportunity to explore it further in the future, particularly by testing riblet designs in different flow conditions or on full-scale aircraft components. 

This was an opportunity to see how small, nature-inspired details can influence something as technologically complex as an aircraft. It reinforced the idea that innovation often begins with subtle changes, and that solutions for the future of flight can emerge from studying the natural world. It strengthened my passion for aerospace engineering and gave me confidence in contributing to the industry’s efforts to build a quieter, greener, and more sustainable future for aviation.