I've previously looked at the basics of naval radar, but there is still a lot of ground to cover. This time, our main subject will be noise. In a typical, simplified model, the radar reflects off of its target and comes back, showing up as a clean blip. In practice, it's far from that simple. Every radar return off of a target comes back mixed with other signals - reflections from the sea or other nearby objects, random electrical noise, echoes from previous pulses, signals from other radars and even intentional interference in the form of jamming. The radar designer's task is to figure out how to boost the signal and suppress the noise, and then distinguish between the signals they want and the ones they don't, and they have come up with a variety of tricks to do so.¹

A scope with various forms of interference on it

But before we get to noise, it's worth taking a digression to talk about how the radio spectrum is divided up, usually into a set of "bands". There are several different systems, the two most common both using letters to designate the bands. One is normally used for most radar, while the other is the standard for electronic warfare. The latter system uses letters A-M, from long to short wavelength, while the former uses an array of letters including C, K and L, which can cause confusion. We'll primarily use the radar system, which is in wider use, and which can be found in the table below: Read more...

WWII began with the ability of aircraft to sink capital ships still an open question. It turned out that while it wasn't impossible, it was very difficult, and the British² looked at options beyond the typical bombs and torpedoes to make the job easier.

https://youtu.be/5DuJaGFkCmg The longest-running was the buoyant bomb, or B-bomb, intended to take advantage of the vulnerability of ships to underbottom explosions. The basic idea was a bomb that would be dropped in front of a moving ship, and sink with the momentum of its fall, then rise back to the surface as the ship passed over it, detonating underneath its target. Work began in the early 20s, although the initial plan may have looked more like an air-dropped drifting mine than what the B-bomb became. The idea was to drop the 250 lb bomb, carrying 113 lb of Torpex, directly in front of an enemy ship. The bomb would plunge to 50', then slowly ascend back to the surface. If it was in the right place, it would hit somewhere in the aft half of the ship and go off, doing significant damage.³ If it missed, then after about 10 minutes, enough water would leak into the buoyancy chamber built into the body to send it to the bottom. In practical terms, this wouldn't have been easy, but it might well have worked better than conventional level bombing, particularly for aircraft which couldn't carry torpedoes. Although the B-bomb was ready when war broke out, the RAF showed no particular interest in using it, and despite development work continuing into 1943, it never saw service. Read more...

One of the weapons currently on the horizon of naval warfare is the laser. While laser weapons have been discussed since the 60s, and the first laser weapons went to sea in the early 80s, it's only in the last decade that there's been a serious prospect of deploying lethal lasers in action. But there's a great deal of confusion around the potentials and limitations of laser weapons. How do they work, and what will they do to naval warfare?⁴

An Argentine aircraft attacks the British in the Falklands

Before I get to those questions, I should probably address something I'm sure many of you are asking about. Yes, the first operational laser weapons were deployed in the early 80s, aboard the ships of the Royal Navy. This device, known as Outfit DEC, was not designed to directly damage attackers. Instead, it was a blue-light optical dazzler, designed to blind the pilots of incoming aircraft. Even looking away wouldn't be enough, as the wavelength would cause the canopy to fluoresce. It is claimed that some ships deployed with Outfit DEC to the Falklands, and there are persistent rumors that several Argentine aircraft crashed while attacking the fleet as a result of their pilots being blinded. I am skeptical of this, as the air war has been extensively studied and every loss analyzed in detail. No Argentine aircraft flew into the terrain inside San Carlos water, and reports on Outfit DEC don't give the names of the pilots involved.⁵ Read more...

As usual, it is time for our open thread. Talk about whatever you want, even if it's not naval/military related.

The time is approaching for our next virtual meetup (July's being in-person), and I had a thought for adding some discussion fodder by watching an episode of Victory at Sea, a series of half-hour WWII documentaries. They're on YouTube, and generally have lots of interesting footage. Thoughts?

2018 overhauls are The 15" Battleships, Museum Ships - United States, LA Fleet Week 2016, Information, Communication and Naval Warfare Part 1, So You Want to Build a Modern Navy - Aviation Part 3 and Anti-Submarine Warfare - WWII - The OIC. 2019 overhauls are Lion and Vanguard, Wolverine and Sable, Italian Battleships in WWII, So You Want to Build a Battleship - Trials and Commissioning, How to Build a Battleship - 1942 and The Maximum Battleship. 2020 overhauls are Nuclear Weapons at Sea ASW Parts one and two, Coastal Defenses Part 5 and Spotting.

Reader Suvorov continues his series about Confederate commerce raiding during the American Civil War.

In our last installment, we covered the Florida, the South’s first success in overseas construction of commerce raiders. Although the crew of the Florida ended up debilitated by yellow fever, their ability to dash through the blockade and return safely to Southern soil was another mark against the Union Navy.

George Preble

In response to criticism, Secretary of the Navy Gideon Wells and President Lincoln cashiered Commander George Preble, the unfortunate captain of the Oneida, which had been one of the ships that had failed to capture Florida. While it’s possible that Preble was being scapegoated, there does seem to have been, in the early years of the war, a problem in the command climate of Union ships: one author recounts that a captain off the coast of New Orleans was supposed to have hailed passing ships to try to obtain permission from his admiral to pursue a Confederate vessel. Read more...

Even before surface-to-air missiles went to sea, there was interest in fitting them with nuclear warheads. Surprisingly, this had less to do with trying to take out multiple targets at once, unlikely as air combat tactics adapted to the threat of nuclear warheads, and more to do with increasing the probability of a kill, particularly in the face of heavy ECM, which could be expected to push miss distances out past the limits of conventional proximity fuzes.

Talos missiles aboard Little Rock

A secondary benefit was the ability of a nuclear warhead to damage enemy nuclear weapons beyond its normal damage radius, thanks to an effect known as preinitiation. This happens when neutrons begin a chain reaction before the fissile material is fully compressed, and can cut the yield of a megaton bomb to only a few kilotons for as much as five minutes after the first weapon goes off. Initially, plans were made to fit Talos with a warhead version of the Mk 12 nuclear bomb, although more for use in the planned land-based variant that would be used by both the Army and Air Force. In the Army's hands, it would be used both for shooting down airplanes and as a surface-to-surface missile, but both services eventually gave up on Talos, leaving it as an all-Navy show. The W12 warhead died fairly quickly as well, as it was too heavy, and a new warhead was developed for the missile, the 5 kiloton⁶ W30. Read more...

Earlier in the month, I hosted a meetup aboard Iowa and John Schilling, CatCube and Randy M came to visit. One of the highlights was a chance to visit Turret 1, which was opened up since my last visit to the ship two years ago. We got in through the hatch on the back of the turret, although I didn't think to take pictures.

The inside of Turret 1

The first thing I noticed was how spacious the inside of the turret was. This is the result of the rangefinder that was originally inside the turret being removed in the 1950s. This made it much more spacious than the previous turrets I've been in, most notably one aboard Massachusetts. Read more...

I recently watched the 1992 movie Under Siege, about a plot to steal nuclear Tomahawks from the battleship Missouri as she's on her way home from Desert Storm. It's thwarted by Stephen Seagal, playing an ex-SEAL turned cook, who has to go up against a rogue CIA operative (Tommy Lee Jones) and the ship's XO, with the aid of a Playboy Playmate who came onboard as part of the cover story for the attack. It is about the best possible movie that could be made up from those ingredients, and I actually enjoyed it.

Because Missouri was still in service while the movie was being filmed, most of it was shot aboard Alabama. The filmmakers worked around this quite well, and even I usually couldn't tell they were aboard the wrong ship unless I went looking for it. The one exception was some scenes on broadway, which is much narrower on a SoDak. Also, there were a couple of sets, most notably the bridge, where the conning tower seemed to have been magically removed. (Pearl Harbor did the same thing, and I suspect that filming in the cramped space around the actual conning tower isn't really possible. Running the ship from there would have been hard enough.) But on the whole, it was well done, and I rarely found myself actually looking for mistakes. There were also things which impressed, even though they were wrong. At the end of the movie, the bad guy launches two Tomahawks towards Hawaii, and there's references to things like TERCOM and DSMAC on the screens, precisely the systems which would have made it impossible to actually shoot Tomahawks at Hawaii. (Of course, they then trigger the self-destruct on the Tomahawk after Seagal gets the codes in a fight with the main bad guy, a system that doesn't actually exist.) Read more...

It's time once again for our open thread. As usual, talk about whatever you want, so long as it isn't culture war.

I had a great time two weeks ago on the Iowa, and thought I would post this photo of those who showed up.

John Schilling, Randy M, me and CatCube

2018 overhauls are Ship History Missouri Part 1, So You Want to Build a Modern Navy - Coast Guard Part 2, The QF Gun, Yalu River, DismalPseudoscience's review of Mikasa and German Battleships in WWII. 2019 overhauls are Signalling Parts two, three and four, The Pepsi Fleet?, Falklands Part 16 and Pictures - Iowa Communications. 2020 overhauls are The Last Sailing Battle, Naval Rations Part 2 and Part 3 and Nuclear Weapons at Sea - Light Attack Parts one and two,

The basic principle behind radar is fairly simple. The radar sends out a pulse of radio waves, some of which bounce off of whatever happens to be in their path. These reflections are picked up by the radar and used to build a picture of whatever happens to be out there. But this simplicity masks deep complexity, as various portions of this are implemented in different ways, and even from the earliest days of radar at sea, ships carried multiple sets optimized for different missions.⁷

The first USN at-sea radar test aboard the USS Leary, 1937

The first radars, as developed in the late 1930s, were extremely crude. A transmitter would send out a short pulse through an antenna shaped to focus the signal in a particular direction, and then switch over to listening for the echos through the same antenna.⁸ The returned signal would be displayed using a device known as an A-scope, a special cathode ray tube. Essentially, the A-scope would draw a horizontal line for each pulse, deflected up (or down) depending on the received signal strength at a given range as measured by the round trip speed-of-light delay. An object reflecting the beam would appear as a spike or trough on the line, depending on how the A-scope was set up. This gave the operator precise knowledge of ranges, a vast improvement over previous methods, but only in the direction the antenna was pointing. Checking different bearings required rotating the antenna, often manually, and left the operator with the job of keeping track of what was going on around him. This didn't make it impossible to use radar data to build a picture, as the British did with the Chain Home radar feeding information to the Dowding system, but this took lots of manpower and organization. Read more...