Rippled coating could improve fuel efficiency on aircraft

Researchers at Surrey University have used near-infrared radiation to selectively treat a colloidal dispersion of polymers in water to create various solid riblets.

Military aircraft have long used ‘efficient’ coatings on the fuselage — while, more recently, some commercial airliners belonging to carrier EasyJet were treated with a similar coating. This method essentially smooths out microscopic hills and valleys that naturally occur in paint coating.

The primary effect of this is to prevent the build-up of debris, including ice, dirt and seawater, but there is also a modest drag-reduction effect. However, the process is uniform and completely unselective, whereby anionic nanoparticles are pulled electrostatically into the pores.

By contrast, the Surrey researchers aim to introduce arrangements of so-called ’riblets’ in sizes ranging from less than a millimetre to a couple of centimetres.

They use a process called infrared radiation-assisted evaporative lithography to treat a colloidal dispersion of polymers. Essentially, the hotter spots evaporate more quickly and the plastic particles are then guided there as the evaporating water is replaced.