This is the second half of John Schilling's two-part effortpost on SCUBA diving, originally written for Data Secrets Lox. The first part covered basic recreational diving, while this one looks at more advanced topics.

This time we’ll be focusing on technical and professional diving. Note that these aren’t strictly the same thing. “Technical diving” refers to anything beyond the limits of no-decompression open-cycle scuba diving. And there are amateurs who learn those skills for recreational purposes, e.g. visiting interesting or historically significant shipwrecks at 40-80 meters. There are also professionals who can do their jobs using nothing but recreational-grade scuba gear and techniques. But for our purposes, I’m just going to fold them both together into the broad category of stuff beyond ordinary recreational diving.

Most of this is going to be stuff that’s more difficult, more expensive, and more dangerous than ordinary recreational diving, but also more rewarding. Let’s start with the risks. I already listed all the things that could kill you in the course of a brief recreational dive to no more than forty meters, if you aren’t careful. Here’s a few more to worry about if you’re going really deep. Read more...

This is the first half of a two-part effortpost on SCUBA¹ diving originally posted at Data Secrets Lox by John Schilling. This part is devoted to the basic principles of scuba diving and the hobby of recreational diving, while the second half will cover more advanced technical diving, and professional or military diving activities.

Diving is not actually all that difficult, at the most basic recreational level. You’re not going to suffocate or run out of air – there’s plenty of that no more than twenty meters (65’) away, and you’re buoyant enough that if you drop your weight belt you’ll float to the surface in seconds. You shouldn’t be diving deep enough or long enough that even an emergency ascent will give you “the bends”. And the sharks aren’t going to eat you.

But it absolutely does require training, about two full weekends’ worth, because there are some ways to kill yourself very quickly if you do something stupid and the not-stupid things, while easy to describe, are neither obvious nor instinctual. Your first few dives need to be with an expert watching closely to make sure you don’t do anything stupid. At that point you scan safely spend an hour or so looking at already-known Neat Stuff down to about twenty meters, in calm open water in daylight. Highly recommended if you live or vacation anywhere with good diving, because there’s a lot of neat stuff to see. There are several agencies that certify recreational divers; PADI (Professional Association of Diving Instructors) is probably the largest, but the others have their fans (and occasional holy wars). Without a certification card from one of them, nobody will rent you dive gear, nobody will fill your air tanks, and nobody will let you on board their dive boats. Read more...

It's time once again for the regular Open Thread. Talk about whatever you want, so long as it isn't Culture War.

Overhauls are my review of Batfish, the list of US museum ships, Italian Battleships in WWII, NWAS Light Attack Part 1, NWAS Cruise Missiles Part 1, Zumwalt Part 2, my review of Hornet, Military Spaceflight Part 2, and for 2024, Military Spaceflight Parts nine and ten, Air Attack on Ships Part 6 and Southern Commerce Raiding Part 9.

I'm going to designate tomorrow (8/2) at 1 PM Central Time (GMT-6) as the Schelling Point for anyone who wants to hang out in voice chat on the Discord. I will probably be there, but might have other things going on.

As a companion to my series on US military aircraft, I'm going to take a similar look at the military aircraft of our allies, and then of the rest of the world. Note that this is less comprehensive than the US version, as there are a lot of countries operating a lot of planes, and I am not going to tear my hair out trying to find all of them. But I will mention the major players, along with a few interesting oddities.

Fighters

Fighters worldwide play much the same role they do for the US, although it is worth noting that nobody outside the US, Russia and China operates bombers, so for all of our allies, fighters also handle the high-end ground attack work. Adoption of US fighters has been reasonably widespread, but major countries often build their own as a matter of national sovereignty and to support their aerospace industries. Read more...

The utility of space-based imagery was obvious almost from the moment that people thought of putting cameras in space, but for the first decade or so of spaceflight, the ability to launch things was limited to only the USSR and the US, and they used this capability primarily for military purposes, with limited exceptions for communications and meteorology.

Dick Gordon sets up a Hasselblad camera in the Apollo 12 simulator

Because of the cloak of secrecy that shrouded both side's reconnaissance satellite programs, the first good look anyone in the wider world got at the Earth from space was through cameras carried aboard manned spacecraft. At least on the US side, these were Hasselblad handheld cameras, and produced stunning photos that had nowhere near the resolution of something like Corona. But they were still of great interest to researchers in fields like agriculture, forestry, hydrology and geology, who had a new window onto the planet that they studied. Pressure began to build for a dedicated platform to produce low-resolution imagery for Earth scientists, finally culminating with the flight of Earth Resources Technology Satellite-1, later known as Landsat-1, in 1972. Read more...

One of the major issues that I didn't discuss in my early coverage of military spaceflight was operations by nations outside of the United States, most notably the Soviet Union. The Soviets were somewhat slower to adopt satellite reconnaissance than the United States, as they were able to take advantage of the openness of American society to gather information on their enemy. Instead, they spent the late 50s protesting the "illegal" American satellites, although development began on recon satellites shortly after Sputnik went up.

A Zenit capsule

The Soviets faced several challenges. They were shorter on technical skills than the Americans, limiting the number of programs they could run at one time, and because, unlike the US, they had not spent the last decade and more building up their strategic reconnaissance capabilities, they were also short on the sophisticated cameras that would be needed by a reconnaissance satellite. Fortunately, they could kill two birds with one stone, by using the same Vostok capsule that carried Yuri Gagarin into orbit, but with a bunch of cameras instead of an astronaut. This was very useful, as it meant the cameras and film were kept in a pressurized environment, and the cameras could be reused, although it required a significantly larger booster than the American system.² This program, codenamed Zenit, lasted until 1994, although with significant evolution over its lifespan. The early versions had no ability to alter their orbits, and relied on batteries, limiting them to only a few days in orbit, while later versions could stay up for two weeks thanks to solar panels and could remain over a specific area for most of their operational life. Read more...

After the attempt to visit Hornet fell through, we took a look around for other museums to go to. There was discussion of trying to hit Jeremiah O'Brien, but timing ruled that out, and eventually we decided to stay in the area and go to the Oakland Aviation Museum, which we had found out about because we noticed a sign to it on the way up from San Jose. And I was pleasantly surprised by what I found.

Website

The museum is small and kind of out of the way, on the outskirts of Oakland airport. But the collection was better than I would have expected for a museum that is pretty clearly taking whatever planes it can get. Inside, there's a replica of the Vin Fiz Flier, the first airplane to fly coast-to-coast (not nonstop, and definitely not without crashing), a MiG-15, a couple of light planes and a few helicopters. There was also a room of Navy artifacts and models, which allowed me to recycle a lot of the material I had prepared for Hornet, and another room dedicated to Jimmy Doolittle, which was mostly notable for having a Norden Bombsight on display in a replica bombardier's position, as well as discussing events that I think are overdone. Read more...

It is time once again for our regular Open Thread. Talk about whatever you want, so long as it isn't Culture War.

Cassander, long-time commenter here, is looking for a managerial data science/product management role, preferably in aerospace. Email tint.michael@gmail if you have suggestions or leads.

Overhauls are Falklands Part 3, Coastal Defenses Part 3, Coastal Defenses Part 8, On the Border of Land and Sea, and for 2024, Distributed Maritime Operations, Military Spaceflight Parts seven and eight and Air Attack on Ships Part 5.

In 1979, the Shah of Iran was overthrown, bringing a new government, headed by Ayatollah Khomeini, into power. Khomeini's vision of an Islamic state was very different than what had been there before, and the country was in chaos even before students seized the US embassy and kept its diplomats hostage for 444 days. Saddam Hussein, who had recently seized control of Iran's neighbor Iraq, was irritated by Khomeini's description of him as a "puppet of Satan", coupled with calls for the majority Shia population of Iraq to overthrow the Sunni-dominated government. There was also the question of who should control the Shatt al-Arab, the river formed by the confluence of the Tigris and Euphrates that serves as an important outlet from Iraq to the sea. In 1975, Saddam had signed a treaty drawing the boundary at the center of the river, but in September 1980, he tore that up, reasserting Iraq's traditional claim to the entire river and ordering his forces into an Iran that he expected would be unable to effectively resist due to the tumult of the revolution.

In this, he would be gravely disappointed. Although his forces made reasonable gains early on, Saddam was not a particularly good commander and the war unified the Iranian people behind the new government. By the end of 1980, the Iraqi offensive had ground to a halt, and after staying stalemated through 1981, the Iranian counteroffensive in 1982 drove Iraq back to its start lines, often making use of human wave attacks, massed charges driven by religious fervor that were sometimes used to clear minefields in the fastest and highest-casualty way possible. But there was also enough technical skill left in Iran to conduct operations against the Iraqi Navy and generally make the Iraqi coastline unsafe, slashing oil revenues. After a key pipeline through Syria was closed, the Iraqi war effort was sustained only by loans from Kuwait and Saudi Arabia,³ as well as material and technical support from both sides of the Cold War, neither of which was eager to see Khomeini's version of Islam spread. Read more...

Things have settled enough that I'm going to give my current thoughts on the recent fighting between Israel and Iran.⁴ This is approximately half commentary on the specifics of that conflict, and half broader lessons we can take from this and apply more generally.

I think the first and biggest lesson is that the results of battle, and thus the lessons to be drawn, are really contingent on the details of who is doing the fighting, and on the difficult-to-measure aspects of their competence and capabilities. If you look at the Ukraine War, ground-based air defenses (GBAD) looks formidable. Nobody dares fly over the enemy, and the most effective air-launched weapon is a long-range glide bomb. If you look at Iran, Israel has effectively neutered Iranian GBAD and rules the skies, striking what it wants. So, all we can definitively say is that Russia and Ukraine appear to be broadly matched in capability, while Israel is much better than Iran. We can't say for sure how Israel (or the US) would fare against Russia. Read more...