Right from the very first days of flying, when Otto Lilienthal studied the flight of birds to design his first gliders, the world of aviation has taken inspiration from nature.
Now with an increasing focus on ways to make flying more efficient to reduce emissions, manufacturers and designers are copying tricks from the natural world.
For example, Sharklets, fitted on Airbus A320neo aircraft, are wing-tip extensions which resemble a shark’s dorsal fin. Airbus says they significantly reduce the size of the wingtip vortex, thus reducing induced drag and making flying more efficient.
Sticking with sharks, Lufthansa Technik, the maintenance, repair and overhaul arm of Lufthansa Group, is working on AeroSHARK, a “bionic film that successfully mimics the skin of sharks and optimizes the airflow”. The film reduces friction and can save fuel and therefore CO2 emissions.
Airbus has also trialed formation flying across the Atlantic, taking inspiration from the way geese fly, to research the fuel saving potential. Another project at Airbus is the eXtra Performance Wing, to test new wing technologies partly inspired by how birds soar and change their wing shape in flight.
Along with AeroSHARK, Lufthansa Technik has another interesting project inspired by flora and fauna: AeroFLAX, as in the flax plant. As part of Innovation month at AeroTime, we caught up with Christian Seifert, product manager AeroFLAX, to find out more.
What is AeroFLAX?
We’ve all heard of flax. It’s used to make linen and the oil from its seeds, linseed oil, is very nutritious. But how can it be used for aircraft cabin parts?
Amplitex fabric. Credit: Bcomp
AeroFLAX is a material combination based on flax fibers and biological resin that Lufthansa Technik has developed with Swiss company Bcomp, based on the company’s Amplitex technical fabric. The German MRO company sees it as a renewable and lighter weight replacement for parts made out of glass fiber or carbon fiber, such as sidewall and ceiling panels.
“I’m a craftsman. I like working with natural materials like wood and I love the flax approach,” Seifert tells AeroTime in an interview. “To bring natural materials into something that is really high tech means a very high effort is needed. But it’s super interesting and I think this is the way to go in the future because it wouldn’t make any sense to stick to fossil materials.”
It may seem unlikely, but along with the plant being easy to grow, Seifert says flax fabric has very low density and good mechanical properties. The pre-impregnated fabric is strengthened with ribs, which boost stiffness but also allow the fabric to be flexed, similar to how veins work on leaves. Combining it with a resin creates a material that can lower a cabin component’s weight by 20% compared to current glass fiber parts.
In development since 2019, one of the big challenges for the AeroFLAX team was flammability, because natural fiber is highly combustible. Seifert said it took over a year of trial and error to get the right combination of flame-retardant additives to pass the tests, one of which involves using Bunsen burners (which we all remember from school!) to burn the sample.
PowerRibs strengthen the flax fabric. Credit Bcomp
Are airlines interested?
The first components to be made from AeroFLAX are not yet certified, but Seifert said this could happen in 2023. Sadly, just making something out of natural products isn’t enough to catch the attention of commercial airlines, which have to think about cost. AeroFLAX costs three times as much as glass fiber parts right now because the product is still at the laboratory phase and not in scale production, though costs will of course come down once production starts.
For airlines, the weight savings are the big draw, Seifert explains, because less weight means lower fuel consumption and lower fuel bills. Lower fuel consumption also means fewer emissions.
“I think I started talking about this in 2019 and at that point, everyone was saying that’s nice to have, but no one is paying for it,” Seifert admits. “But when we showed that we have the bio-based material and the 20% weight saving potential, this combination was very interesting for the airlines.”
For example, Lufthansa Technik has calculated that replacing 40 pieces of sidewall and 150 seat covers in a typical Airbus A320 cabin would save a medium double-digit kilogram figure in terms of weight. This weight saving could translate into annual operational savings of more than 3 tons of fuel and more than 11 tons of carbon dioxide emissions.
What does it look like?
Lufthansa Technik and Seifert hope that one day the entire interior cabin lining could be made of AeroFLAX.
In rendering, you can see how the AeroFLAX components could look in the aircraft if left to show their natural state. In reality, airline customers would likely want to paint or print something on the parts to give it a more high-tech look, Seifert said.
Rendering of sidewall panel with AeroFLAX. Credit: Lufthansa Technik
Seifert first spoke about AeroFLAX at the AIX interiors trade fair in Hamburg in 2019. “No one really liked the natural design,” he said. But when AIX returned after a pandemic-related pause in June 2022, the feedback was different. According to Seifert, the idea of having a window or panel built into the side wall to get a glimpse of the more natural looking flax-based product underneath “got a lot of interest at the show”.
Seifert says Lufthansa Technik is not the only one looking at how to use natural composites. Bcomp, the partner on the AeroFLAX project, has a lot of experience in the automotive industry.
“I’m very happy that we’re not the only industry looking into that. A lot of natural composite activities are happening right now. And I’m very happy about that. Because this is another piece of the puzzle that fits into CO2-neutral flying and mobility.”