Renewable materials options for aircraft wing structures
Ambitious targets for the reduction of CO2, the pursuit of independence from fossil resources and the demand for cost control have driven efforts to search for raw materials from renewable resources for aeronautical applications. In general, polymer composites reinforced with endless fibres offer good mechanical properties, making them ideal candidates for lightweight design, compared to conventional materials such as aluminium. Advanced fibre composites made from renewable resources, which have similar mechanical properties to “traditionally” produced carbon fibres reinforced polymers, would therefore contribute to lower fuel burn in operation due to lower structural weights than aluminium. Additionally, these composites have the potential to decrease an aircraft’s carbon footprint. Bauhaus Luftfahrt was able to identify ramie fibres as a suitable raw material meeting the requirements in aerospace in terms of material’s stiffness and strength.
With an increase of wing’s aspect ratio, a double-digit improvement of the aerodynamic performance can be expected, but, consequently, at a higher structural wing weight. To maintaina benefit on overall aircraft level, high aspect ratio wings out of renewable materials have to be the same weight or lower, compared to established aerospace materials. A first assessment performed by Bauhaus Luftfahrt showed that, for high aspect ratio wings, renewable materials lead to a similar outcome in terms of wing weight reduction, compared to conventional carbon fibres reinforced polymers. As a next step, besides mechanical properties, further characteristics of renewable raw materials to sustain operational conditions must be studied.