[HN Gopher] Air Independent Propulsion Could Create Silent Kille...
       ___________________________________________________________________
        
       Air Independent Propulsion Could Create Silent Killer Submarines
        
       Author : jdmark
       Score  : 19 points
       Date   : 2021-08-29 19:28 UTC (3 hours ago)
        
 (HTM) web link (nationalinterest.org)
 (TXT) w3m dump (nationalinterest.org)
        
       | shadilay wrote:
       | >Could
       | 
       | >In the 1990s, submarines powered by Air Independent Propulsion
       | (AIP) technology entered operational use. Though the concept
       | dated back to the 19th century and had been tested in a few
       | prototype vessels, it was left to Sweden to deploy the first
       | operational AIP-powered submarine, the Gotland-class, which
       | proved to be stealthy and relatively long enduring. The 60-meter
       | long Gotlands are powered by a Stirling-cycle engine, a heat
       | engine consuming a combination of liquid oxygen and diesel fuel.
       | 
       | AIP is not new and has been operational for decades.
        
         | HPsquared wrote:
         | Things move pretty slowly in the world of naval architecture.
        
         | tomjen3 wrote:
         | Those Gotland class submarines are another tier entirely
         | compared to other submarines, so I don't think it is fair to
         | dismis this entirely as having been operational for decades.
        
           | pge wrote:
           | The first Gotlands were launched in 1995, and I'm fairly
           | certain that German-made diesel subs (Type 209s) were being
           | retrofitted with Stirling engines well before the Gotlands
           | begin construction in 1992.
        
       | ju-st wrote:
       | (2018)
        
       | FridayoLeary wrote:
       | What kind of submarines don't kill?
        
         | teekert wrote:
         | Why can't AIP create silent non-killer submarines?
         | 
         | I imagine if you're studying life in the deep ocean, a silent
         | submarine is nice.
        
           | gpm wrote:
           | AIP isn't quieter than a batter powered submarine, it's
           | quieter than a nuclear powered submarine.
           | 
           | Unless you're doing ridiculously long research dives (in
           | which case batteries don't suffice), or you care about noise
           | on the surface (where you would use a traditional air burning
           | diesel engine to recharge) it doesn't seem like this brings
           | any advantages.
        
         | gpm wrote:
         | Research submarines?
        
           | BoxOfRain wrote:
           | I heard Greece was planning to do tourist dives of the wreck
           | of HMHS _Britannic_ (Titanic 's almost as ill-fated sister
           | ship) in the Aegean via submarines, but I'm not sure if
           | anything came of that. The wreck is remarkably well-preserved
           | and in far shallower water compared to her sister.
        
         | chrisseaton wrote:
         | 'Hunter Killer', or just 'Killer', is a different role to
         | 'Subsurface Ballistic Nuclear', so not all submarines are
         | 'Killer'.
         | 
         | The 'largely around coastal waters' (littoral) should hint at
         | this.
        
       | [deleted]
        
       | ggambetta wrote:
       | Hmmm. Better get some satellites above Polyarny, just in case.
        
       | Someone1234 wrote:
       | Here is a brief (3 minute) silent video that explains what AIP
       | is:
       | 
       | https://www.youtube.com/watch?v=8rBL54Hdixw
       | 
       | AIPs are a _big_ competitor to replace diesel submarines for the
       | reasons the article sets out. Nuclear has superior performance,
       | but the costs aren 't in the same ballpark as either AIP or
       | diesel (particularly cost to do nuclear safely).
       | 
       | I could see the US retiring out a handful of nuclear subs and
       | replacing them with AIPs simply as a cost saving measure (e.g.
       | SSBN mission). It would reduce the cost of the submarine fleet
       | while saving face in terms of sub count and on-paper capabilities
       | (although then we go down the rabbit-hole of "is the US sub fleet
       | oversized?").
        
         | jasonwatkinspdx wrote:
         | > AIPs are a big competitor to replace diesel submarines
         | 
         | AIP is a supplementary system used by diesel submarines, not a
         | replacement for them. They don't have sufficient power for
         | anything but slow quiet cruising. AIP equipped subs will retain
         | diesel generators for faster sprints, and greater endurance
         | while transiting on the surface or via snorkel.
         | 
         | The two basic technologies for AIP are fuel cells and sterling
         | engines. Both are deployed successfully at the moment. The
         | video above is a neat summary of a 2nd generation fuel cell
         | system that uses an onboard reformer to generate H2 from
         | diesel, avoiding the downsides of H2 storage.
        
         | Wistar wrote:
         | Also, the wikipedia write-up:
         | 
         | https://en.wikipedia.org/wiki/Air-independent_propulsion
        
       | [deleted]
        
       | 29athrowaway wrote:
       | For marine mammals like cetaceans, sonar is equivalent to hearing
       | an incredibly loud sound that makes your ears bleed.
        
       | kryogen1c wrote:
       | > While old diesel submarines needed to surface in a matter of
       | hours or a few days at best to recharge batteries, new AIP
       | powered vessels only need to surface every two to four weeks
       | depending on type.
       | 
       | > a Gotland class submarine is reduced to just 6 miles per hour
       | if it wishes to remain submerged at maximum endurance
       | 
       | two to four weeks submerged while idling? hardly seems like an
       | improvement over diesel boats. also, what is the limiting factor?
       | are they literally out of fuel, since they cant just snorkel to
       | recharge batteries? or do they carry some kind of liquid oxygen
       | maker? if they can make LOX, why dont we compare how long before
       | diesel refueling is required?
       | 
       | weird amount of detail in the article. too much to be clickbait,
       | not enough to be an examination.
        
       ___________________________________________________________________
       (page generated 2021-08-29 23:01 UTC)