Lighten the weight of its wings and an airplane immediately becomes more fuel efficient. Researchers at Delft University in the Netherlands, along with collaborators at aluminium giant Alcoa and GTM Advanced Structures, have redesigned airplane wings so that they are made up like a sandwich. The central layer is a strong mesh of fibers laminated with metal; on either side lies a thick aluminium layer. Not only does this create a light, robust wing, the resulting structure is also insensitive to metal fatigue, which plagues wings made just of aluminium. Besides, the new wings are stronger than the carbon fiber reinforced plastic wings that have recently been used in aircraft such as the Boeing 787. The researchers estimate that using their new "green" design allows a weight reduction of about 20 per cent compared to the Boeing 787. They translate this to a worldwide fuel and maintenance savings of $100 billion for the airline industry.