Ships only sink when you let air out and water in. This fundamental truth was a problem during the age of the gun, as gunfire, while quite effective at disabling the enemy, is not particularly good at either. Even the occasional shot "between wind and water" was unlikely to sink the enemy very quickly. Shot also had a second problem, in that the guns to deliver it were large and expensive, and required big ships to carry them.

Cornelis Drebble

The obvious way to solve this was to use explosives, and the first man to make a serious attempt at this was Dutch inventor Cornelis Drebbel, who developed what we now know as the spar torpedo as a weapon for his submarine, the first ever to successfully navigate underwater. His concept was extremely simple, a bomb on the end of a stick, which would be set off in contact with the enemy ship. Details about use are unclear, but he was a consultant to the British Admiralty for several years before they apparently became disillusioned with the idea and fired him. Read more...

It's time for our usual Open Thread. Talk about whatever you want, so long as it isn't Culture War.

Overhauls are Signalling Part 4, EABO and LAW and for 2023 my review of Fort MacArthur and Military Spaceflight Part 3.

We finally come to the conclusion of reader Suvorov's series on Confederate commerce raiding in the Civil War, which has stretched from strategy and leadership through privateering, efforts to procure ironclads and the efforts of Raphael Semmes and the British-built Alabama, wrapping up after the end of the war.

Shenendoah, the last of the Confederate commerce raiders

In aggregate, the Confederacy destroyed nearly 250 merchant ships; about one thousand other American-flagged vessels were transferred to a foreign flag, in part to avoid risk of seizure and in part to reduce insurance premiums. Percentage-wise, around 5% of Northern shipping was destroyed. Other portions of the U.S. merchant fleet switched flags, hoping to avoid being targeted by raiders. Ultimately the size of the U.S. merchant fleet was roughly cut in half during the conflict (although, due to merchant ships flagging out, this does not imply a corresponding loss in commerce to the States.) The Union government spent around $3 million deploying about a hundred warships and other vessels to run the commerce-raiders down, mostly unsuccessfully. Read more...

During the interwar years, it became increasingly obvious that dive-bombing was by far the most accurate way for aircraft to deliver ordnance, although true dive-bombing, conducted at steep angles, required special aircraft that could only carry limited loads of bombs. But when all of the alternatives were either ineffective or expensive and lower-performance, the dive bomber reigned as the supreme anti-ship weapon, so long as the target wasn't too heavily armored.

A Ju 87C showing its folding wings

Nor was dive-bombing limited to naval aircraft. The US Army Air Force procured versions of the SBD and SB2C naval dive-bombers, as well as the A-36, a version of the P-51 Mustang fitted with dive brakes and intended to keep the North American production line running because they had exhausted their funds for fighters, but had money left over for attack aircraft. But the most famous ground-attack dive bomber came out of Germany in the form of the Ju 87 Stuka. Known for its distinctive siren, which became almost synonymous with the Blitzkrieg, the Ju 87 was fitted with a unique automatic dive system. The pilot would set intended drop altitude on his altimeter and open the dive brakes, which would automatically nose the airplane over, and he would then select his dive angle using a series of marks painted in the cockpit, which would be aligned with the horizon. At the appropriate altitude (at least 1500' above the ground, if the pilot wanted to survive), a light would come on, and a single button would drop the bomb and pull the plane out of the dive, even if the pilot was incapacitated by the 6G pullout. Besides its use against land targets, the Germans also used the Ju 87 against ships, even planning to make a modified version, the Ju 87C, the primary strike aircraft of their carrier, Graf Zeppelin, where it would serve as both dive and torpedo bomber.¹ But in a rare moment of sense, the Germans realized at the outbreak of the war that although she was 85% complete, Graf Zeppelin wouldn't be of much use, and called off the whole program. The Stuka did see service against ships in the Mediterranean, most notably badly damaging Illustrious in early 1941 despite her armored deck and later driving the Royal Navy from the seas around Crete. But these were only possible because the British lacked good fighter cover, as German attempts to use Ju 87s over Britain the previous year had shown that the aircraft was too slow and vulnerable in the face of serious opposition, and Germany didn't have a viable replacement in the pipeline. Read more...

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

Notable recently is Iran taking a strong lead in this year's Brown Award, by capsizing a frigate in port. They will be the first repeat winner outside of the USN, which is certainly good news.

Overhauls are The Pepsi Fleet? (where I have another update based on continuing research), Naval Rations Part 2, NWAS Light Attack Part 2, Norway Part 3, Zumwalt Part 2 and for 2023, Military Spaceflight Parts one and two.

Work on anti-satellite weapons began almost as soon as it became apparent that satellites had military utility, although initial work was driven by fears that the Soviets would put nuclear weapons in orbit. For a variety of reasons, this wasn't particularly well-founded, and it meant that the initial American systems, which used nuclear warheads of their own, were retired relatively quickly. Focus instead shifted to non-nuclear systems. The Soviets had preferred these from the start, designing coorbital systems that would come alongside and blow the target up from close range, while the Americans preferred to go straight up and intercept the target at high speed. The Soviets also looked extensively at in-space weapons, to the point of unsuccessfully launching a laser battle station in the closing years of the Cold War.

A DF-21 launcher

With the end of the Cold War, ASAT development quieted down for about 15 years before things began to heat up in the mid-2000s. China, who had had a quiet ASAT program since the 60s, began live tests of a direct-ascent missile in 2005, said to be based on the DF-21 ballistic missile with a different kinetic kill vehicle. These culminated in a hit on a weather satellite in 2007, which caused more debris than any previous event in the history of satellite tracking. 3,438 pieces were eventually tracked, and because the satellite was in an 850 km orbit, decay is slow, and NASA has estimated that 30% of pieces larger than 10 cm would remain in orbit past 2035. There was global outrage, and while China has run several subsequent tests, these have been against ballistic targets, which don't produce orbital debris. There have also been reports of more powerful ASAT systems, some of which are credited with capability against targets in GEO. Read more...

The military utility of satellites quickly set the US thinking about ways to counter Soviet space presence. Given that this started in the late 50s and early 60s, it should be no surprise that the initial efforts, Project Mudflap and Program 437, were nuclear-tipped. But these, based on small islands in the Pacific, had limited engagement windows and using them would require accepting the rather dramatic consequences of high-altitude nuclear weapons on satellites and those on the ground.

This had been justified by fears of the Soviets putting nuclear weapons in orbit, but in the early 70s, Project 437 was shut down as it became increasingly clear that the Soviets weren't going to do that. As for other Soviet satellites, their recon birds had to return their film for processing, limiting their utility during a war, while communications was done from orbits far too high for the Thor missiles used in Project 437 to reach. But things began to change in the late 70s, as the Soviet ocean surveillance program ramped up, exposing US forces to real-time space surveillance and producing a resurgence of interest in ASAT. The downsides of using nuclear weapons in space meant that this version would involve getting a direct hit on the target satellite. And because the target had to be killed quickly, the weapon would need to be far more mobile than the old Thor, resulting in a return of the air-launched concept that dated back to Bold Orion, although this time with the high-performance F-15 as a launch platform.² Read more...

It's time once again for our regular open thread. Talk about whatever you want, so long as it isn't Culture War.

I'm going to do a virtual meetup next Saturday, 7/13, in the Naval Gazing Discord channel, at the usual time, 1 PM Central (GMT-6 or so). Should be fun if you want to talk about whatever happens to come up.

Overhauls are Rangefinding, Impressment, my pictures from Iowa's goat locker, The 3T Missiles - Launch Systems, Coastal Defenses Part 8, my review of the Jeremiah O'Brien and Pampanito and for 2023, Thoughts on the lost submersible, my review of the Kansas Aviation Museum, The German Navy in the Americas and my post thanking the base commander for the long lines at last year's Tinker Air Show.

Throughout WWII, the single most effective way of delivering high explosives to ships was dive bombing. This is exactly what it sounds like, the aircraft diving towards the target before releasing the bomb, the performing a high-G pullout to avoid following the bomb into the target. It was originally developed during WWI to attack land targets, as pilots realized that it allowed them to place bombs far more accurately,³ although the fragile aircraft of the time were limited to fairly shallow dives.⁴

Curtiss F8Cs, the first US dive bomber

Dive bombing nearly died off in the years immediately after WWI, abandoned in the enthusiasm of airpower advocates for level bombing, but it was adopted by the US Marines and Navy in the late 20s, using fighters equipped with light bombs for support in ground fighting. Initially, they used fairly shallow dives, but the target had a tendency to disappear under the nose of the aircraft, and it was soon realized that steeper dives not only solved this problem and improved accuracy, but also were far harder to defend against. The plunging dive bombers were generally difficult to see before they began their dives, and once in a dive, the rapid change in range meant that heavy AA guns were ineffective, while lighter AA weapons had only a narrow window to work against the diving aircraft.⁵ The basic technique they used would remain standard throughout the dive bomber's life: approach at 10,000' or so, then push over into a steep dive, 70° or more. As he dove, he would aim at the target attempting to compensate for wind and the movement of the ship. The bomb would be dropped during the dive, and the pilot would then pull out and fly away at high speed and relatively low altitude. What altitude the pull-out was done at varied, with early tests taking place at 1000' or so, although later aircraft had to do so at greater altitude to avoid plowing into the ground.⁶ The pullout itself would often subject pilot and plane to 6G or more, enough to make the pilot's vision gray out, which generally limited the tactic to smaller aircraft.⁷ Read more...

Satellites have found a number of military uses: reconnaissance and intelligence, communications and navigation. But all of these require the satellites to be intact and functional, and that raises the possibility of denying the enemy these capabilities by degrading or destroying their satellites. That's right. It's finally time for ASAT.⁸

Bold Orion

First, a few words of definition. We can divide ASAT weapons into two fundamental categories: direct ascent and coorbital. Direct-ascent weapons, as the name suggests, ascend directly from the surface to intercept their target, while coorbital ASAT involves launching into the same plane as the target, then approaching and using some sort of warhead at close range. Direct-ascent is conceptually simpler and cheaper (as it can be executed by a fairly small missile if it's in the right place), and can use the target's own speed in place of a warhead if it can get a hit.⁹ The downside is that it requires incredibly precise guidance, with a typical launch window being a second or less, even if the system is fitted with a nuclear warhead. Coorbital ASAT, on the other hand, needs a full-size booster, but once the price for that has been paid, the guidance problem is greatly simplified, removing the need for a nuclear warhead even with 60s technology, and it is theoretically possible to leave the ASAT shadowing the target, then kill it at a moment's notice when war breaks out. The US has always preferred direct-ascent systems, while the Soviets and Russians often went for coorbital ones. Also worth noting early on is that not all satellites are created equal from the perspective of ASAT systems. An imagery satellite a couple hundred kilometers up is a far easier target than a GPS satellite or a comsat in GEO that are tens of thousands of kilometers up. This is more true for direct-ascent systems than for coorbital systems, but it affects both of them, and news stories about LEO systems that bring up the danger to GPS and the like should not be trusted. Read more...