Shark-inspired surfaces increase fuel efficiency of aircraft
The particular qualities of shark skin have inspired a German company using lasers to increase fuel efficiency in aircraft.
Laser specialist 4JET and aircraft paint supplier Mankiewicz have introduced a laser process for the creation of fuel-saving 'riblets' – like small ridges – automatically lasered directly onto painted aircraft surfaces.
The technology, dubbed ‘Leaf’ for Laser Enhanced Air Flow, uses the principle of laser interference patterning to quickly create fine lateral grooves in the uppermost layer of aircraft paint. Such riblets have been proven to reduce drag by up to 10 per cent, which can result in fuel savings of one per cent for commercial long-haul airlines. Clearly, this has the potential to produce huge savings across the aerospace industry.
The process – while still in the development stage – already yields industrial throughput levels and has passed initial qualifications for durability.
Removing paint by lasers is a well-known technology but has so far proved to be too slow to create the high density of riblets required to achieve 'shark skin' effects. Instead of creating the riblet grooves with one focused laser spot 'line by line', 4JET says it has now found a way to speed up the process by a factor of about 500 using the principle of laser interference patterning.
Here the laser beam is split up and recombined on the surface in such a way that the electric field oscillations of the light waves superpose in a controlled manner. This superposition creates a distinct pattern of dozens of alternating equidistant lines of high and almost no intensity within one single laser spot. This enables the creation of 15 kilometres of riblets – equal to about a square metre of riblet surface – in less than one minute.
4JET says that, to add even more benefits; Leaf works without any consumables. It allows riblet geometries to be adjusted depending on their location on the aircraft. The paint dust and vapour created during the process is evacuated and the process does not require post processing. The technology also enables the processing of curved or riveted surfaces and – thanks to its long focal distance – can be integrated with existing robotics used for paint removal or printing operations in aircraft maintenance.
'We are looking forward to actively writing another chapter in the history of aviation coatings and shaping the future of sustainable aircraft. With 4JET we are glad to have such a competent partner of the laser industry at our side and look forward to the future cooperation and commercialisation of this ground-breaking new method to save fuel and thus contribute to a greener future,' said Andreas Ossenkopf, director and head of aviation at Mankiewicz.
4JET CEO Jorg Jetter added: 'We are excited about the progress so far and the tremendous opportunities of our new partnership with Mankiewicz. Leaf could not only be opening up an entirely new market for our company, but deliver a significant contribution to cut down CO2 emissions in the aviation sector.'
This story was featured in our latest feature article on aerospace: CFRP machining taxis for take-off, in which Tim Gillett discusses how lasers are being used to machine composite materials in the production of aircraft.