A new paint that could reduce drag on airplanes, wind turbines and ships has an unlikely inspiration--the scales of fast-swimming sharks.
Shark's scales have evolved in a manner that significantly diminishes drag, or their resistance to the flow of currents. The challenge was to apply this knowledge to a paint that could withstand the extreme demands of aviation--temperature fluctuations, intensive UV radiation and high speeds.
Yvonne Wilke, Dr. Volkmar Stenzel and Manfred Peschka of the Fraunhofer Institute for Manufacturing Engineering and Applied Materials Research IFAM in Bremen developed not only a paint that reduces aerodynamic drag, but also the associated manufacturing technology.
The paint involves a sophisticated formulation of nanoparticles, which ensure that the paint withstands UV radiation, temperature change and mechanical loads, on an enduring basis. "Paint offers more advantages," explains Dr. Volkmar Stenzel. "It is applied as the outermost coating on the plane, so that no other layer of material is required. It adds no additional weight, and even when the airplane is stripped – about every five years, the paint has to be completely removed and reapplied – no additional costs are incurred. In addition, it can be applied to complex three-dimensional surfaces without a problem."
The next step for the scientists was to clarify how the paint could be put to practical use on a production scale. "Our solution consisted of not applying the paint directly, but instead through a stencil," says Manfred Peschka. This gives the paint its sharkskin structure. The unique challenge was to apply the fluid paint evenly in a thin layer on the stencil, and at the same time ensure that it can again be detached from the base even after UV radiation, which is required for hardening.
The scientists says they have calculated that when applied to every airplane every year throughout the world, the paint could save a volume of 4.48 million tons of fuel. This also applies to ships: The team was able to reduce wall friction by more than 5% in a test with a ship construction testing facility.
This article courtesy of the Fraunhofer Institute for Manufacturing Engineering and Applied Materials Research.