From the dustbin of history -
The RB211 originally was to use a composite fan blade (called Hyfil, I think) that would have been wonderful - except that it couldn't pass the bird & icing tests. They had to redesign it in titanium. This delayed the 1011 project enough that Delta, for one, bought a Plan B (DC-10's, later resold to other operators). Delta was the first airline to operate 747, DC-10, AND L-1011.
Modern composites, had they been available to RR in 1969, might have made a huge difference in the Lockheed sales.
More L-1011 history