Hacker News Reader

Hacker News

Comment by OneEyedRobot | Hacker News Reader

Parent Full thread

OneEyedRobot

Am I crazy or is that AIP stuff not all that much better than batteries?

This https://www.aspistrategist.org.au/future-submarine-coming-up...

gives me 4.5 MJ/L density for fuel

This, just chosen randomly https://www.cei.washington.edu/education/science-of-solar/ba...

Gives me 670 Wh/L as an upper value...and a MJ 277 WH...so 2.4 MJ/L

Unless I'm utterly wrong, I'd just wait for batteries to get better. New Musk investment, 'The Unterseebat Company'

View on HN

You're not crazy. That's exactly what Japan chose to do for the latest block of Sōryū-class attack submarines. They removed AIP engines from the design and replaced them with a huge pack of lithium batteries. Underwater endurance is still limited, but there are significant operational advantages to the simpler battery based system for defensive submarines that will never deploy far from Japanese waters.

I'm wondering whether I'd prefer to not be stuck underwater with a huge pack of lithium cells, or to not be stuck underwater with a tankful of liquid oxygen and another tank full of diesel?

Probably 'stuck underwater' is the key phrase here.

I'm attracted to the idea of battery submarines mostly because you'd be latching onto a huge (and growing) commercial development world. Much less need for highly specialized tech.

Thinking it through, assuming that propulsion is the gating factor for submarine adoption (maybe it isn't), what happens when pretty much any nation can afford a silent undersea navy?

The next thing I'll hear about is recharging station surface ships.

Propulsion isn't the gating factor for submarine adoption. The engineering and precision manufacturing is just extremely difficult all around. For one example there are only a few shipyards in the world with the right equipment and expertise to weld together hull sections. Most countries that want an attack submarine have to buy them used from an ally, or spend $100M+ with one of just a few European or Russian manufacturers. And even once you have a submarine it costs a fortune to maintain and operate safely. Most countries barely use the subs they have because they're in poor condition or lack trained crew.

https://www.thedrive.com/the-war-zone/41075/canadian-submari...

Full size submarines can recharge their own batteries on the surface using diesel engines. Only some small, short-range submarines rely on other vessels for recharging.

Would you prefer to get stuck underwater with a nuclear reactor? :)

Battery is a kind of AIP but not AIP engines.

Let's be real they won't be far from Japanese shore in the near future.

(and the batteries can always be upgraded)

Reply on news.ycombinator.com