I wonder if this belongs in Aviation History and Nostalgia?It's probably a bit simplistic to say that composites led to the downfall of RR in 1971. The decline ( and I do not want this to lead to acrimony) perhaps started with the premature death of Adrian Lombard without a natural successor. The actual composite fan blades you are thinking of ('Hyfil') were a product of 1960s RAE research. RR placed most of their faith in the Hyfil blade fitted to the RB211 : it was the birdstrike test which showed then to be fatally flawed and subsequent replacement with a titanium fan. The consequential problems of delay, cost overrun and failure at that time to reach contractual specification ( the subject aircraft was, of course, the L1011 Tristar) resulted in the dismissal of most ( with the exception of 3) of the Board of Directors, the insolvency of RR and the Government take over. As for later developments...you will doubtless read more up to date wisdom than I possess on this subject.