The toroidal propeller

MrSalts

Joined Apr 2, 2020
2,767
Interestingly, a lot of this efficiency increase and noise reduction came from an extreme evolution of the "winglet" added to the ends of airplane wings - (Note, Airbus uses the term "sharklet" in an attempt to avoid a lawsuit for stealing a design developed by Aviation Partners. Airbus did get sued and they lost).



and more recently the double winglet.


737 MAX AT WINGLET




And the winglet research started to reduce noise and gain efficiency based on the silent flight of owls which has been attributed to their upswept wing tips when gliding in for a kill. Of the various subspecies of owls, those with the most upswept tips were the quietest and most efficient gliders. https://simpleflying.com/boeing-winglets-airbus-sharklets/

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The leading edge feathers also contribute to noise reduction but do not improve efficiency


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I love when engineering is willing to learn from 3-billion years of nature's experimentation and exploitation of physics. The practice is known as biomimetic engineering or just biomimetics.

https://en.m.wikipedia.org/wiki/Biomimetics
 

Thread Starter

cmartinez

Joined Jan 17, 2007
8,218
If they increase efficiency of boats and planes and being the principle of reciprocity, could they also result in higher efficiencies going the opposite direction, that is for wind turbines?
Ian and me were thinking the same thing ... and what's more, wind turbines' noise is an outstanding annoyance. So this tech might make them quieter too ... the one thing to consider is going to be the cost of manufacturing the blades. But I'm sure these guys are already on it, and it's just a matter of time for us to hear news about it.
 

SamR

Joined Mar 19, 2019
5,031
Interestingly, a lot of this efficiency increase and noise reduction came from an extreme evolution of the "winglet" added to the ends of airplane wings
In Marine Prop speak, it is called cupping. They have been cupping marine propellers for decades before any winglets ever appeared. Cupping not only increases energy transfer but also prevents cavitation slippage upon heavy full throttle accelerations from a standing start. Something not wanted when trying to pull up a couple of water skiers from a standing start or when pushing a heavy tow up the Mississippi River. The long-curved blade design was also instrumental in reducing propeller cavitation noise and increasing energy transfer on submarines and tow boats long before aeronautical winglets.
 

nsaspook

Joined Aug 27, 2009
13,079
That doesn't look much different than the screw on a submarine. This picture is an older one, I'm sure they've made improvements.

View attachment 286287
There is a entire navy department for designing the most efficient and quiet marine propellers for boats, ships and underwater weapons.
https://www.navsea.navy.mil/Home/Sh...ent-Links/Naval-Foundry-and-Propeller-Center/
It's a secret sauce science that's likely far advanced of what these guys have recently engineered. Time will tell if theirs is a practical design.
 
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