Let's talk about [old] submarine propeller designs (nothing confidential)

[NiceSub]

Originally Posted by FPSchazly

I would not consider that particular Victor-III prop design to be an old design, I would consider this to be an old design (from Alfa):



I am by no means a propeller expert or fluid dynamics voodoo witch doctor, but the design referenced in your first link seems to decrease the pressure along the leading edges of the propeller blade in order to reduce cavitation.

As to the ring around LA props (which may be getting into classified territory ), I imagine it's also there as a form of cavitation reduction to reduce the prop tip cavitation. I read an article a while ago stating that there are three forms of propellor cavitation, and cavitation at the tip is one of them. It's where the blade is rotating the fastest, so tipping over the blades, like with that Victor-III prop, seemingly increases prop area without increasing the speed of the blade as much.

Anyone well-versed in propellers, please feel free to correct my terminology.

What are those small propellers next to the large one? What is their task?