sentences:  In the race to achieve better fuel economy, more thrust and less weight & noise from jet engines, designers have refined the blade design and materials to extract more thrust for any given fan disk area.One significant improvement is to make blade chords wider and, more recently, alter the blade geometry to give it a scimitar-like shape.Further refinements include making the blades from a light material such as titanium and to manufacture them with a hollow cross-section.