Military Embedded Systems

And then there's submarines


May 30, 2017

Ray Alderman

VITA Standards Organization

WARFARE EVOLUTION BLOG: Submarines were harder to count than aircraft carriers in my previous blog. According to scattered web information, there are about 533 submarines in the oceans today, operated by 40 countries. But that number moves around, mostly because (1) there are a number of new submarines coming into service and (2) it?s hard to say how many antiquated Russian, Chinese, Iranian, and North Korean submarines are still operational.

China launched a new Jin-class missile submarine and India launched a new Scorpene-class attack submarine in January 2017. Russia launched their new Yasen-Class attack submarine in April.

There are about 120 nuclear submarines in the oceans according to the World Nuclear Association, operated by six countries: U.S., Russia, China, France, India, and UK. Most submarines in the total are diesel-electric powered (about 353). All U.S. submarines are nuclear-powered.

There are 60 newer submarines operating today with AIP (air-independent propulsion) systems, according to reports. These submarines use a Sterling-cycle engine, that mixes liquid oxygen with diesel fuel or uses oxygen-hydrogen fuel cells to drive electric generators. Regular diesel submarines can only stay down for a few hours before they have to surface, run their engines, and charge their batteries. AIP submarines can stay down for weeks without surfacing. Nuclear submarines can stay down for months. Anytime a submarine surfaces or raises a breathing snorkel to run their diesels, they risk being detected by our ASW (anti-submarine warfare) systems. Also, nuclear submarines can travel faster submerged that diesel or AIP subs. Our nuclear-powered attack submarines can travel more than 33 miles per hour. Their top speed is classified, so it can probably hit 40 miles per hour underwater.

To read more Warfare Evolution Blogs by Ray Alderman, click here.

Submarines are divided into attack, ballistic missile, and cruise missile versions. They can be classified by size too. The largest are the Russian Typhoon class at 574 feet long, and the U.S. Ohio class at 550 feet, both ballistic missile submarines.

For attack submarines, the Russian Yassen-class is about 450 feet long, and the U.S. Virginia-class is 377 feet. The smallest are the mini-submarines operated by North Korea (Yugo/Yono/Yeono class at 69 feet long), and Iran (Ghadir class at 95 feet). Any submarine with less than 150 tons of water displacement is considered a mini-submarine (the Typhoon displaces 24,000 tons, and the Ohio-class displaces 18,700 tons by comparison). The smaller mini-submarines carry 10 to 30 people, depending on the mission. The larger U.S. submarines have crews of 140-150 people. The Russian Typhoon-class carries about 160 people.

Breaking down the opposition: North Korea, China, Russia, and Iran

- North Korea has 70 diesel submarines, according to Pentagon 2015 reports: 20 old Russian Romeo-class, 40 homebuilt Sang-O "Shark” class coastal submarines, and about 10 of the Yono-class mini-submarines. How many remain operational is a big question. These boats never go far from shore, do not go down very deep, and are primarily for harbor defense and laying mines. Their latest submarine, a used Russian Golf-class boat they bought in 1993, is their Sinpo-class (215 feet long). The sail was modified with the addition of a vertical missile launch tube. This submarine was observed at the docks by satellite intelligence photos in late 2016, and is considered to be a test platform for their nuclear-tipped missile program. While all their submarines are considered antiquated, noisy, and easy to track, 50 of them left their docks in August 2015, and the South Korean navy lost them, even with extensive acoustic sensors and hydrophones in the water.

- China has 15 AIP powered submarines, five nuclear-powered attack submarines, four nuclear-powered ballistic missile submarines, and about 50 diesel-electric submarines according to reports (total of 74). In 2006, a Chinese diesel attack submarine surfaced within torpedo range (5 miles) of the USS Kitty Hawk carrier group off the coast of Okinawa. In 2015, another Chinese attack submarine stalked the USS Ronald Reagan strike group off the coast of Japan for half a day before it surfaced. The U.S. Navy is not saying whether they knew the submarines were nearby or not. China was producing two submarines per year. They just completed their new massive submarine construction site at Huludao, and can now produce four submarines per year.

- From what I could assemble from different sources on the web, Russia has about 13 ballistic missile submarines, eight cruise missile submarines, and 38 attack submarines (total of 59). Of those, 38 are nuclear-powered, 20 are diesel-powered, and one is AIP-powered (O2-H fuel cells) At any given time, only about half of them are operational, according to reports, so I could be off by one or two in my count. In 1990, just before the USSR collapsed, they were operating 270 submarines (63 ballistic missile boats, 72 cruise missile boats, 64 attack submarines, and nine auxiliary submarines). You can see that the Russian submarine fleet today is just 23 percent of its former size under the USSR flag. Besides their missiles, these submarines are equipped with traditional 533mm torpedoes, and their Shkval super-cavitating torpedo.

- Iran has four old Russian Kilo-class diesel submarines, one homebuilt Nahang submarine (400 tons), and about 12 Gadhir mini-submarines. None of these submarines can vertically-launch ballistic missiles or cruise missiles. But they may have some anti-ship torpedo-tube-launched (TTL) missiles. Their primary weapons are 533mm and 324mm torpedoes, including their new Hoot super-cavitating torpedo, based on the old Russian Shkval design. According to intelligence reports, they are developing and constructing new 1000 ton (Qaa’em-class) and 600 ton (Fateh-class) submarines, but information is sketchy.

U.S. submarine inventory

By comparison, The U.S. has 55 attack submarines, four cruise missile submarines, and 14 ballistic missile submarines in service for a total of 73. From what I could put together from the web, we have 18 Ohio-class (4 converted to cruise missile submarines), 36 Los Angeles-class, three Seawolf-class, and 16 Virginia-class in operation (including the USS Indiana commissioned in April 2017). All of these are nuclear-powered. The Virginia-class is replacing the older Los Angeles class submarines over time. Contracts were awarded in May for the design of the Columbia-class submarines, to replace the Ohio-class in 2021. The U.S. presently has the capacity and facilities to produce two submarines per year.

In March 2015, the French attack submarine Safir, “sunk” the USS Theodore Roosevelt carrier in war games off the coast of Florida. In 2006, the small Swedish AIP-powered submarine HSMS Gotland (1,600 tons) executed several attack runs and “sunk" the USS Ronald Reagan with multiple torpedoes during war games. The accompanying ASW destroyers, airplanes, nuclear submarines, and helicopters in the attack group never once detected the presence of the Gotland. Both Russia and China regularly send their submarines out to stalk and practice torpedo runs on our carriers when they come into their regional waters. We do the same, but since they only have one carrier each, it’s not hard to find and track them.

The typical range of our enemy’s conventional torpedoes today is about 9 miles, and their average speed is about 45 miles per hour. At maximum range, that means you have 12 minutes to react, from the time the torpedo launch is detected until it hits your ship (9/45=0.2 hours x 60 minutes/hr =12 minutes). However, Russia developed super-cavitating torpedoes during the cold war (Shkval, with a range of 9 miles and speed of 230 miles per hour) and Iran has their own version (Hoot, with a range of 6 miles and a speed of 220 miles per hour).

I don’t have the space here to explain how the super-cavitating torpedo works, so look it up. Then, do the math and you will see that you have 2.5 and 1.6 minutes (respectively) to react to these torpedoes. And, there are some wake-homing and variable-speed torpedoes: they have a longer range at slow speeds, to follow ships, and then sprint to the target at high speed. Obviously, we need to detect enemy submarines long before they come into torpedo range (10-20 miles out). The U.S. Navy is now deploying and testing their new SSTD (surface ship torpedo defense) system on our carriers, cruisers, and destroyers. This first-of-a-kind system can detect torpedo launches in the water and launch anti-torpedo missiles against them in seconds.

An anti-ship cruise missile launched 50 or 100 miles away, and flying at 500 miles per hour, will hit the target ship in six minutes and 12 minutes, respectively. So, torpedoes are a serious reaction-time threat to ships when you consider the 2.5 and 1.6 minute torpedo time-to-target numbers. This is especially concerning when you consider the incidents where our carriers didn’t detect Chinese, French, and Swedish submarines within torpedo range. For your knowledge, DARPA [Defense Advanced Research Projects Agency] calculated that it takes an ICBM, carrying a 1 megaton nuclear warhead, 1,600 seconds to travel from the launch pad in Russia to Washington. That’s 26 minutes 40 seconds. Somewhere at the Pentagon, there’s a spreadsheet that has all our enemy missile and torpedo speeds and ranges, with their time-to-target numbers calculated. I’ve just given you a few examples here, to make a point.

Next time

Every succeeding war in history has significantly reduced the “kill chain”, the time it takes to detect, fix, track, respond, and destroy an enemy threat. With the development of hypersonic missiles and laser weapons, we will again reduce the kill chain from hours to minutes, and then from minutes to seconds. In our next episode, we’ll take a look at the kill chain over time, and the weapons that keep compressing those time-to-target numbers.