Sword of Light: Humanoid Self-Propelled Artillery

Chapter 309 Powerful Cannons

Because this place, namely the Watergate Bridge, is less than forty kilometers from the nearest coast.

Therefore, it is already within the range of a 406mm naval gun.

Unlike bombers, which are unable to conduct precise bombing at night due to limited visibility, bombers cannot even report coordinates.

Since there is no reference point, reporting coordinates is not very useful.

Moreover, bombers dare not fly too low at night, which further limits their bombing accuracy.

In contrast, the cannons of battleships no longer depend on weather conditions or the pilot's visibility.

Normally, once artillery fires beyond three or four kilometers, the gunner can no longer see the target clearly.

In such situations, artillery observers rely on radio to calibrate the artillery's impact points.

Therefore, day and night were completely irrelevant to the large-caliber guns on battleships with a range of thirty to forty kilometers.

The ship equipped with 406mm naval guns was the Iowa-class battleship, the largest battleship in the U.S. Navy. The ship responsible for bombarding the Watergate Bridge was the USS Missouri, also an Iowa-class battleship.

Battleships were inherently long-range weapons, their large-caliber shells giving them long-range strike capabilities. The 406mm, 50-caliber Mark 7 gun, designed for battleships in the 1930s, was developed in accordance with the requirements of the Hawthorne Naval Treaty.

The meaning of "fifty times" is that the barrel length is fifty times the caliber. For example, the barrel length of a cannon with a caliber of 4206 mm is 20.32 meters.

This artillery can fire armor-piercing shells weighing up to 1,225 kilograms to a distance of 42 kilometers, with the shells taking up to 90 seconds to reach their target.

The Iowa-class battleships, equipped with this type of gun, were directly fitted with nine 406mm guns, arranged in groups of three, with two turrets at the bow and one at the stern. Only the gun barrels were exposed on the turrets; the turrets themselves extended into the fourth or fifth deck of the ship.

Each barrel of the 406mm Mark 7 gun weighs 108 tons, and each barrel can be raised and lowered independently.

The combined weight of the nine gun barrels is close to one thousand tons, and that doesn't even include the weight of the turrets and other mechanical structures. However, one thousand tons is nothing for the Iowa-class battleships, which have a standard displacement of 45,000 tons and a full-load displacement of 55,000 tons.

Of course, the turrets of these guns were also enormous, with four levels, from the gunpowder supply level to the muzzle level, requiring 79 people to maintain them. The Iowa-class battleship could fire two shells per minute from its 406mm guns; this was the rate of fire per single barrel, so the entire Iowa-class battleship with nine guns could achieve a rate of fire of 18 rounds per minute.

In the Battle of Okinawa in April 1945, the US Navy assembled its largest battleship fleet in history, consisting of eighteen battleships and twenty-five cruisers, to bombard the islands from the coast. Such a concentration of large-caliber naval artillery has never been replicated.

The Iowa-class battleships were typically equipped with approximately 1,200 406mm shells. These shells included live ammunition as well as 130 combat armor-piercing or high-explosive shells per gun barrel.

In addition to the armor-piercing rounds weighing up to 1,226 kilograms, there is also the MK13 high-explosive round, which weighs only 862 kilograms.

However, when fired from a 406mm naval gun, it can inflict devastating damage on ground targets, creating a crater 15 meters in diameter and 6.1 meters deep upon explosion, and destroying trees within a 400-meter radius. In contrast, a 155mm howitzer can only create a crater 5 meters in diameter and 1.8 meters deep.

The reason why high-explosive shells are lighter than armor-piercing shells is that most of the internal space of these shells is used to fill explosives, and the 220 kilograms of explosives naturally result in terrifying explosive power.

Of course, the MK8 super heavy armor-piercing projectile's weight of 1,225 kilograms is not for nothing; it can penetrate up to 9 meters of concrete or 330 millimeters of armor.

These shells made the 406mm guns of the Iowa-class battleships roughly equivalent to the 460mm guns of the Japanese super battleship Yamato.

These shells were launched using six bags of propellant, each weighing fifty kilograms, which required two people to manually load into the propellant loading device.

Of course, in addition to armor-piercing shells and high-explosive shells, the 406mm artillery also has an unconventional type of ammunition, namely the artillery shell.

It should be noted that during the war in the early 1950s, the US Navy was commissioned to modify the 280mm tactical gun shell Mark 8 for use with the 406mm naval guns on battleships.

The Mark 8 shell was fitted into an existing MK13 shell casing and modified to accommodate different propellants and fuses. It was equipped with a 1.5 to 20 kilotons warhead, roughly equivalent to the power of the bombs dropped on Kojima and Nagasaki at the end of World War II, and these shells were given the new designation MaeK 23.

Fortunately, these new shells were not available until 1956, when they passed testing. The three Iowa-class battleships, USS New Jersey, USS Wisconsin, and USS Iowa, were then converted to receive them. A dedicated, 24-hour guard warehouse was built inside the second ammunition magazine of the turret.

The warheads were stored in a protected cabinet separate from the shells. The task was to attach the warheads to the shells and prepare them for launch.

A total of fifty of these shells were manufactured. Each Iowa-class battleship was equipped with ten MK23 shells, which meant one shell per gun barrel plus one spare.

This means that a battleship could fire nine Mark 23 shells, generating a total strike force of 135,000 to 180,000 tons.

So on paper, this is the most powerful artillery salvo in the world!
Since a 15,000 to 20,000-ton warhead is enough to destroy an entire city when it explodes in the air, it is very interesting to consider how the fleet will use this weapon.

After all, although the navy has aircraft capable of delivering missiles, the use of naval artillery can provide accuracy, evade enemy anti-aircraft fire, and can be used in any weather conditions.

Of course, this weapon was also believed to be able to inflict devastating damage on enemy fleets, destroying or repelling an entire fleet with a single shot.

Although it is unclear from US naval records whether these shells were ever loaded onto ships, such matters remain classified.

However, records show that the USS Wisconsin, an Iowa-class battleship, fired a training shell in 1957, so there is reason to believe that the ship may also have real guns on board.

Of course, although the era of battleships lasted for more than a century, fortunately, this MK23 shell was never actually used. After all, only the Japanese had ever tasted two shells since the invention of the gunnery weapon.

(End of this chapter)