View Full Version : 20-100% Efficiency Increases in Propellers? Sharrow/Toroidal/Open Fan Architecture

30th May 2023, 03:55
At the risk of being seen to be putting the cat amongst the pigeons (alternatively seen as exposing my own relative ignorance): I’m yet to see any mention of equivalent “Sharrow” or toroidal propellers here on PPRuNe as is under more discussion in the marine and drone spheres.

As a keen non-commercial aviator with a somewhat similar passion for aquatic adventure: I am keen to know what might be the perceived wisdom amongst those with more of an in-depth engineering background? Is there much substance behind some of claimed efficiency improvements in others sectors which might be transferable to aviation? Are they negated in most commercial aviation by the efficiency of high bypass ratio engines etc? Even if yes, are there particular scenarios in which there might feasibly be tangile benefits?

Similarly, I see Airbus and CFM have announced their “open fan architecture” using CFRP (carbon fibre-reinforced polymer) blades - I haven’t found much talk on here.

Apologies for the clickbait subject of the posting. Genuinely curious to know what might be forthcoming whilst appreciating how long such advancements take to reach actual commercial viability.

31st May 2023, 01:29
Difficult, to me at least, to see how it could have much application in aviation other than in fixed pitch applications, drones are an apparent target. See,


31st May 2023, 02:25
Also, difficult to see much improvement in propulsive efficiency vs. a high bypass turbofan. Thanks to years of development, plus the effects of the inlet plus the fan exit guide vanes, the 'fan' portions of modern turbofans are over 90% efficient.
Noise might be a big carrot - especially for some sort of unducted fan application - getting rid of that big, heavy fan cowl would be nice - but the previous generation of unducted fans were horribly noisy.