The public christening of Germany's Type 212 U36 submarine clearly revealed advanced propulsor technology. Credit: Twitter,
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.
The job of submarine engineers is to modify the shape of the propeller to reduce turbulence and reduce the overall noise of the blades as they slice through the water.
Commonly called Propeller Boss Cap Fins (PBCF) in the commercial world, the technology was developed in the 1980s and it’s in fairly widespread use today with thousands of ships sailing with them installed, War Zone reported.
The adaptation of this technology by ThyssenKrupp seems to be pretty much a no-brainer for the military submarine industry.
Still, its migration to the underwater realm is quite intriguing and the complex cylindrical design of the PBVD seen on U36 is clearly more intricate than the fin systems used on its commercial cousins.
This is likely due to the submarine prop’s higher rpm and unique focus on maximum reduction in noise, War Zone reported.
In the past two decades, propulsors have taken the place of traditional propellers on some advanced submarines, including the US Navy’s Seawolf and Virginia class nuclear fast attack boats, which has been a particularly interesting evolution.
But now it seems that some smaller diesel electric subs are also adding something new to their propulsion systems that provides better performance at lower noise levels.
Wärtsilä’s EnergoProFin is one such product that comes with a manufacturer’s claim that it can cut fuel consumption by as much as 5% for large vessels.
Marine Propulsion describes the EnergoProFin’s effectiveness as such:
“Weakening the propeller hub vortex behind the propeller decreases propeller resistance and manifests itself as increased thrust. The deflection of the flow aft of the propeller by the optimized profiled fins reduces the propeller torque. In addition to the improved propulsive efficiency, the new Wärtsilä EnergoProFin propeller can also be applied to reduced propeller-induced noise and vibrations.”
While at this point it is not known if this is, indeed, a breakthrough for the German Navy, we shall soon find out.
Look to the Russians and the Americans to follow suit.
Germany’s Type 212 also features:
A double hull that displaces 1,800 tons submerged, and is made of nonmagnetic materials so that it is not suceptible to detection by magnetic anomaly detectors.
Fuel cells with hydrogen fuel stored in between the outer and inner pressure hulls, allow it to sail underwater for three weeks before surfacing.
While the Type 212 can achieve underwater speeds of up to 23 mph, its sustainable cruising speed is closer to 9 mph while using just the Air Independent Propulsion system.
Intended as a stealthy recon boat and ship hunter, which is why its armament was initially confined to torpedoes. Its six tubes can fire off up to thirteen 533 millimeter DM2A4 Seahake torpedoes.
The German Navy has started installing the capability to fire IDAS fiber-optic missiles while submerged from four-cell magazines in the torpedo tubes.
The German Navy is also working on installing a retractable 30mm Moray autocannon to provide fire support for special forces. In a modern twist, however, the cannon’s retractable mast will also supposedly be able to deploy three Aladin drones.
