Googling for information on the topic leads me to graphs such as this, which suggest that if Beta and advance are optimal efficiency tops out at 85% or so. Some questions:(adsbygoogle = window.adsbygoogle || []).push({});

1) Is the ~15% lost energy converted to heat, or is there some stray kinetic energy in airflow that is somehow unusable as thrust? And to verify then, these prop inefficiencies are not including some losses inherent in the prime mover when measuring 'power' in?

2) Do fans or ducted fans improve on prop inefficiencies (assume sub sonic tip speeds for both)?

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# Aerospace Propeller efficiency and energy loss

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