Although the German Zeppelins get the majority of attention, they were far from the only naval airships used during WWI. The British, after being burned by Mayfly, switched their efforts to non-rigid airships, which are held in shape by gas pressure. The first was bought before WWI, but most effort was focused on heavier-than-air craft. When war broke out, there was an immediate need for longer-duration surveillance than airplanes could achieve, and the first SS class blimp¹ was created by hanging the fuselage of a BE.2 airplane beneath the envelope from an earlier airship. 59 more followed, 14 of which went to France and Italy, each with a crew of two and the capability to carry 160 lb of bombs. They proved very effective as escorts for coastal convoys, able to stay in the air for up to 12 hours. None were able to successfully sink a U-boat, but they were invaluable for spotting them closing in and vectoring in the escort. U-boats were obviously reluctant to surface when airships were nearby, and from mid-1915 onward, only two ships were sunk in convoys protected by airship.

An SS class blimp

But the SS class, which eventually totaled 158 airships in a number of variants, was an extremely simple and short-range design, and work soon began on several other types with greater payload and more range and endurance.² The first was the C or Coastal class, which had a unique 3-lobed balloon, a crew of 5, and the ability to sustain 45 kts for 11 hours. While it did have the ability to carry several bombs, it was still intended primarily as a scout, which required a precise knowledge of its position for communication with surface ships. This was accomplished by a network of shore direction-finding stations, who would triangulate on the callsign of the airship and transmit its position back to it. The increased range also took them within reach of German fighters from time to time, and machine guns were installed, including a position on top of the gasbag, accessed through a tunnel in the bag.³ An improved version, known as the C star, was developed to replace the C class as they wore out. To give them a serious anti-submarine capability, plans were made to fit them with hydrophones that could be lowered from a hover⁴ and circling torpedoes set to run at periscope depth, but this was overly ambitious, and nothing came of it. Read more...

Today is the 78th anniversary of Iowa's first commissioning, at New York Navy Yard.

Military procurement is a weird field. Particularly in western countries, systems are ultimately bought by a group of people who are selected by a process having nothing to do with military expertise.⁵ Often, those charged with asking for systems take advantage of their confusion, with hilarious results. The most obvious examples of these can be found in what systems are called, which can greatly affect the chances of getting funding.

Super Hornets and legacy Hornets fly together

The most obvious dodge is to sell a system as an upgrade of an existing one, when in practice it's a new system that looks a lot like the old one and has the same name. The best example of this is the F/A-18E/F Super Hornet, which was sold to Congress as an evolved version of the F/A-18C/D Hornet in the early 90s. In practice, it was an entirely new aircraft, 4' longer and weighing 30% more. It just looks a lot like the legacy Hornet, which was enough to fool Congress and get the Navy an aircraft it desperately needed to revitalize the carrier strike force for the 21st century. Read more...

It's time once again for our regular open thread.

I recently finished an interesting book, The Great Sea: A Human History of the Mediterranean by David Abulafia. It's a look at the various communities that have dotted the shores of the Med throughout history, and how they used that sea to communicate. Heavy on commerce and sketches of life, rather light on battles and naval power, but still very interesting for a wider look at maritime power.

2018 overhauls are Amphibious Warfare parts two, three and four, Why Military Acquisition is So Hard, Classes and Dreadnought. 2019 overhauls are Rangekeeping Part 1, Commercial Aviation Part 7, Falklands Part 11, So You Want to Build a Battleship - Construction Part 1, Pictures - Iowa Boiler Room and German Guided Bombs Part 2. And 2020 overhauls are Aerial Cruise Missiles, Southern Commerce Raiding Part 1 and the Proximity Fuze Parts one and two.

Most of the naval propulsion systems developed in the aftermath of WWII were intended to replace steam, which had dominated the field for a century. But one alternative was intended not to replace steam, but to generate it using a different heat source. Instead of buring coal or oil, Uranium atoms would be split, giving vast quantities of heat without the need for fuel or oxygen.

Hyman Rickover

Independence from oxygen made nuclear propulsion particularly attractive for submarines, who had been searching for ways to get greater underwater endurance than was possible on batteries. A number of methods had been tested, but results had ranged from "unsuccessful" to "ludicrously dangerous".⁶ The Navy put together a small team in 1946 to begin work on power reactors, led by an engineering officer by the name of Hyman Rickover. It proved to be an inspired choice. Rickover was a difficult man, prone to screaming at subordinates and more than a little obsessive, but also supremely effective at getting things done. He managed to set up an organization known as Naval Reactors under the joint control of the Navy and the Atomic Energy Commission (AEC), which allowed him to evade many of the Navy's bureaucratic obstacles. Read more...

I've previously discussed the use of steam, diesel and gas turbines for warship propulsion. During these discussions, I've mentioned benefits and drawbacks to each, and the obvious way to deal with this is to combine them, an option I've mentioned several times. Today, such combination plants are nearly universal, and it's time to take a closer look at the various ways that different propulsion systems have been made to work together.

HMS Kent, an early COSAG ship

As there are a lot of these, it's first worth looking at the standard nomenclature used to describe them. All combination plants have a specific acronym, which starts with CO for "Combined", followed by a series of letters based on what sort of systems are being combined and how they are combined. For instance, many warships from around 1960 used a steam plant for cruising and added gas turbines for boost power, and their plants are described as Combined Steam And Gas, COSAG. Later, it became common to use one set of turbines for cruising, and take them offline when more speed was needed in favor of a second, more powerful, set of turbines, a system known as Combined Gas Or Gas, COGOG. If the same thing was done with diesels in place of the cruising turbines, it would be known as CODOG, or if both systems could work together, CODAG. Read more...

We have been in space for a decade now, and the last year has gone quite well. The AKX buy is finished, for now at least, with 10 units, and we've got over a million people on Gliese 892, with the first terraforming units being shipped out now. We've also finished adding nitrogen to the Lunar atmosphere, with oxygen addition expected to be finished within two years. It's going to take longer to make Luna fully habitable, due to the lack of surface water, but we should see infrastructure demands begin to fall within the next few years, and can also look at redeploying some of the terraforming facilities to Mars.

I'm also going to say that this is the point when we need to actually get our starting fleet fleshed out. We have 16,421 points left to spend on the various designs. These need to be restricted to tech we had at the start, with one exception. Large and Very Large fuel tanks are allowed, as those should be, IMO, unlocked at the start. To that end, I offer the Suffren class replenishment ship: Read more...

At the end of WWII, the steam turbine was the standard means of powering large warships, turning propellers with reliability and economy. Today, steam propulsion all but gone from the world's oceans, and while large warships are powered by turbines, the turbines in question are turned not by steam, but by combustion gasses.

A turbine is, at its heart, a very simple machine, one that takes high-energy fluid and extracts energy from it, producing lower-energy fluid and rotary motion. A wide variety of fluids can be used, ranging from water (in hydroelectric dams and obviously of little interest in warship propulsion) to steam to the combustion gasses produced by burning jet fuel and air at high pressure.⁷ The last is known as a gas turbine, and it propels not only warships but also likely the last airplane you flew in. Read more...

I've previously covered the development of naval steam propulsion systems, focusing on those used aboard battleships. But from the dawn of the 20th century, other systems were developed to push ships through the water, and today, variants of these systems dominate the marine propulsion landscape.⁸

Diesel engines are checked aboard USS San Antonio

The first serious challenger to steam was the diesel engine, which began to go to sea even before WWI. It had three major advantages over steam. First, it was significantly more efficient at turning the energy of the fuel into rotation, with diesels having two to three times the horsepower per unit weight of fuel per hour as contemporary steam engines. Second, they were easier to run and maintain, requiring fewer crew. These two advantages made diesels attractive to merchant ships, although adoption wasn't universal until after WWII. And third, they were far faster to throttle. A boiler could take an hour to produce steam from a cold start if another boiler on the ship was available, and far longer if the entire plant was cold. This often meant that warships had to operate inefficiently, with more boilers online than they needed at the moment in case demand for steam increased. Diesels could be turned on and reach full power almost immediately, then shut down just as rapidly. Read more...

It's time once again for our usual open thread. Talk about whatever you want that isn't culture war.

Scott Alexander, formerly of the blog Slate Star Codex, where Naval Gazing came from, is back, with a new Substack blog, Astral Codex Ten. And DSL is running the monthly effortpost contest, with 17 entries for January.

2018 updates are Russian Battleships Part 2, Why the Carriers Aren't Doomed Part 4, SYWTBABB - Strategic Background, Early US Battleships, Aegis and Amphibious Warfare Part 1. 2019 overhauls are the Mk 23 Katie, Commercial Aviation Part 6, the King George V Class, German Guided Bombs Part 1, The PHS Corps and my history of Wisconsin. And 2020 overhauls are Operation Crossroads and Battleship Torpedoes parts one, two and three.