The little sub that could


Figure 1: Sweden’s Gotland Class submarine

I stumbled across this vlog post this week which talked about how back in 2006, during a wargame, a Swedish made diesel electric submarine of the Gotland class managed to “sink” a US aircraft carrier. Evading an entire carrier battle group in the process. Should you ask why the nuclear attack sub escort (US carrier battle groups often include a nuclear powered attack sub to deal with this very threat) didn’t go in there and kick Swedish butt. Well in another incident a Gotland class sub successfully out manoeuvred a Los Angeles class attack sub and also effectively “sunk” it.

Suffice to say this came as a bit of a shock to the Americans, who had long assumed that their fast moving carriers battle groups were immune to attack from diesel powered subs. Diesel powered subs are generally slower than modern surface warships, have limited underwater endurance, can only recharge their batteries on the surface, or near to the surface, and when those diesels engines are running they’re pretty noisy. You can probably see why so many of the world’s major naval forces have switched to nuclear powered subs.


Figure 2: Stirling engines rely on temperature difference to create a cycle of pressure, from which motive power can be extracted

However, the Gotland had something of a secret weapon, an Air independent propulsion system based around a Stirling engine. Stirling engines run on a heat cycle driven by a temperature difference. While little more than an oddity for many years, they are commonly used in renewable applications, given that you don’t need any special fuel, you just need something that can create a temperature difference. They are often used for example in CHP plants (and its worth noting Sweden has one of the world’s highest installed capacity of CHP) and solar thermal power systems. There’s also been attempts to use them as a range extender alternative to fuel cells in cars.


Figure 3: Stirling dish solar collectors

Unlike a diesel engine, a Stirling engine is much quieter and has much lower air requirements. Meaning a sub can compress (or cryogenically cool) and store an oxygen supply, doing the same to the same to the exhaust, allowing it to run its engines while still submerged. This not only makes a sub with an AIP much more stealthy, but also means it can remain submerged for much longer. The Gotland has an endurance of 45 days, approaching the endurance of nuclear subs, but with none of the drawbacks. And recall this incident happened in 2006. Since then a number of other navies have developed similar subs with AIP. Most notable of these is the German Navy’s type 212, which uses a hydrogen fuel cell (which would be even quieter and more fuel efficient).

The video I referenced earlier also makes mention of how the Russian navy might be tracking US nuclear powered subs by the radioactive “scent” of their nuclear reactor. I would take this one with a pinch of salt. The Russians are notorious for making bold claims regarding their military which often turn out to not be true. And detecting radiation through many miles of ocean is difficult, given that water is such an effective insulator against radioactivity. Given how noisy Russian subs are, I suspect a US sub would still see them long before the Russians detected the Americans. However, that’s not to say its impossible or that it won’t be possible in the future.

However, the point to be made here is it shows how innovations in one field of science, can often come from a completely different field of research. For example, the internet is largely a product of two things. US military funded research into secure communications networks (that had no central hub and thus would be difficult to destroy, even in a nuclear war). And the fact that particle physics experiments at CERN required large networks of computers talking to one another.

And as I discussed before the USAF funded quite a lot of the early research into the Greenhouse effect, while the US navy were the first to identify that the ice caps were thinning. They weren’t doing this to keep Al Gore happy. Its because, oddly enough the USAF fights most of its battles in the air (and the navy in the sea). And its kind of important to know these things if you’re planning on, say, trying to develop a heat seeking missile.

No doubt this use of Stirling engine as an AIP came about when one Swedish engineer, who worked in the renewables field, was talking shop with another engineer who worked in naval research. So it is no surprise that countries investing in renewables research are going to start finding applications for that technology beyond the field of renewable energy. And its equally not a big surprise that countries who’ve fallen behind in the field of renewables research are shocked when the suddenly find that other countries have gained an edge on them. I’m reminded of a student whose decided to skip the first few weeks of term, comes in to the lecture and he’s now so far behind the others its like were all speaking a different language.

The Americans should be thankful that Sweden and Germany (countries Trump frequently mocks) are friendly nations, and that this was discovered in an exercise. Otherwise they would have likely find out in a shooting war with, say, China (who has a large fleet of AIP equipped subs), or Iran (who has recently sought to purchase or develop similar AIP equipped subs) with the loss of several US carriers.

This is what happens to a country who neglects scientific research or allows the sort of dangerous anti-science, and anti-intellectual rhetoric we now see both sides of the Atlantic, take over. The history of the world is littered with examples of great nations (The Ottomans, the Qing Dynasty, the Japanese Shogunate to name a few), whose empire was brought down by their failure to keep pace with scientific or economic developments. And more often than not, it wasn’t that they didn’t have the technical capability to develop these new ideas. In many cases they were well ahead of everybody else. It was that their experts were actually banned from conducting such research, with whole fields effectively closed off just because the mandarins at court didn’t like the answers they were getting (if you don’t want to hear scary answers, cease to ask scary questions).


Figure 4: An actual sign PZ Myers came across in the US

For example, at the moment the Trump administration is going through the US budget line by line and cutting anything that stinks of climate or environmental research. Imagine this happened back in the 1950’s when the USAF was developing those heat seeking missiles. This would have put the US well behind its competitors in missile technology and its likely that many of the air to air engagements of the cold war would have ended very differently. And similarly if US universities had not been involved with CERN research (possibly because their funding got cut), its likely the hub of the internet and tech companies would now be based out of Europe or China instead of California.

So this little incident should serve as a warning as to what happens when you neglect science. Trump supporters might believe in “alternative facts” but actually “facts” (what we call “science”) can make torpedoes hit carriers and missiles hit aeroplanes. And that tends to be what win wars.

About daryan12

Engineer, expertise: Energy, Sustainablity, Computer Aided Engineering, Renewables technology
This entry was posted in CHP, climate change, efficiency, energy, environment, future, Global warming denial, nuclear, peak oil, politics, renewables, technology and tagged , , , , , , , , , , , , . Bookmark the permalink.

2 Responses to The little sub that could

  1. Pingback: NATO Funding | daryanblog

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