The AKOYA, a new ultra-lightweight two-seat amphibious aircraft from LISA Airplanes, makes extensive use of carbon fiber materials in all the weight-bearing primary structures, including the fuselage, wings and horizontal stabilizer. As a result, AKOYA consumes just 5 liters of fuel per 100 km.
Composite materials are becoming more and more common in the aerospace industry due to their high strength and lightweight characteristics. In an interview with Composites Manufacturing Online, Erick Herzberger, founder and CEO of LISA Airplanes said:
“We chose these materials because they are lightweight — a constraint we have in light aviation — but mainly because we needed to design and produce extremely high-performance aeronautical shapes.” What’s more, thanks to LISA’s patented multi-access technology, the uniquely designed AKOYA can just as easily take off and land on water or snow as on a strip of land less than 220 yards long with no prior modification required. “The AKOYA is the first seaplane equipped with Seafoils that maintain good aeronautics in flight,” he says. The plane also has skis on the retractable landing gear.
The biggest problem the high-tech company based in LeBourget du Lac, France, had to overcome in designing the first airplane with hydrofoils was not to make the aircraft lighter, stronger or more stable, as one might expect. Herzberger said, “Our main challenge in designing the AKOYA was to place the engine at the back of the airplane on top of the vertical stabilizer.” The solution, once again, arose from using composite materials. “We had to place the engine where it would not interfere with water operations,” Herzberger says. “After several round of calculations, simulations, characterization of the materials and tests on samples and representative parts, the conclusion was that carbon composite (CFRP) was the best material to solve this structural design issue because it ensures the engine mount is strong enough to hold the weight. CFRP offers the best compromise between resistance and weight. This was the material to use to support the weight and stresses of the engine, the wings and the hydrofoils.”
The folding wing system with one rotation axis was another critical point where optimized composite materials and finishes made the final design possible. “The part that enables the rotation is fixed on composite structures that are glued on the fuselage,” the engineer says. “A specific distribution of the fibers of the fuselage enabled us to better distribute the stresses of the rotating part.”
Measuring 6.9m/22.6 ft long, with a wingspan of 11m/36 ft, the AKOYA can be stored in a garage; a unique design characteristic allows the wings to be folded to give a total width of only 3.2m/10.5 ft.
All major components of the AKOYA are produced by aeronautical manufacturers in France, Italy, Germany and Austria. All the finishing for coverings is done by hand, making each AKOYA a customized aircraft.
Find out more about the AKOYA