In looking at the specific fuel consumption (SFC) of some aero engines I find that for example, the Rolls Royce Conway turbofan engine had typical cruise SFC of 0.874 lb/(h lbf) whilst the most modern equivalent, the Rolls Royce Pearl has a SFC of ~0.6.

This ~30% improvement in SFC over fifty years doesn't seem to account for the dramatic reduction in fuel consumption of new versus 1960’s aircraft that used the Conway. Is the rest accounted for by just the airframe improvements or am I missing something?

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    $\begingroup$ Editing in data points for the "dramatic reduction" would be beneficial. It helps to compare planes that carry out the same mission too. $\endgroup$
    – user14897
    Aug 5, 2021 at 14:55
  • $\begingroup$ A rule of thumb is that two thirds of improvements are from better engines and the remaining third is from better aerodynamics. $\endgroup$ Aug 5, 2021 at 15:41


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