[Onkel Neal]

The Germans still making masterpiece underseaboats

https://asiatimes.com/2021/01/german...th-efficiency/

In the movie, Hunt for Red October, the Soviet Union launches a new sub with a mysterious new silent propulsion system, called a “caterpillar drive.”

The new technology, revealed in spy photos, leaves it both stealthy and dangerous — a first-strike weapon of the worst kind.

In truth, submarine propulsion is a constantly evolving medium that largely exists in the shadows due to its sensitive nature, Tyler Rogoway of The War Zone reports.

When it comes to submarines, silence is survival, so any way to make a boat quieter and more efficient is seen as potentially revolutionary.

Enter Germany’s new Type 212 submarine, and its odd new propulsor.

Surprisingly, no security measures were taken at the public christening of Type 212 U36, which sported something altogether new — the Propeller Boss Vortex Diffuser (PBVD) — War Zone reported.

Then again, the basic concept behind this technology really isn’t secretive or new as it is also used in commercial applications where increased efficiency even in single digit percentages can mean big fuel savings.

The cylindrical PBVD system sits over the hub of traditional propellers. Its specially machined core works to greatly decrease turbulence that emits from the spinning hub.

This not only cuts down on the propeller’s audible signature, but it also improves propulsion efficiency and thrust.

One of the other factors that contribute to noise levels are propeller blades, which can cause an underwater phenomenon called “cavitation,” where bubbles form along the blade edges and cause noise.