The mighty steel dragon did not bring a sense of reassurance to Admiral Nimitz, who was on the bridge of the USS Franklin, his brow still furrowed and uncertain. Pen, fun, pavilion www. biquge。 info

A few hours earlier, he had received two telegrams in quick succession: the first was from Vice Admiral Hewitt, commander of the transport forces, informing him of the suspected discovery of a German submarine.

Nimitz knew that Hewitt was a very cautious general, and he said that there should be a probability of more than 70%. During this period, there had been German submarine activity in the Caribbean, the waters of Central America, and the east coast, and Hewitt's judgment estimated that there was a ninety percent probability.

The Navy has set up a separate anti-submarine garrison command, and it is expected that at least 20 German submarines will be active in this area, and they will not only gradually increase in number, but also belong to new submarines with more advanced performance -- faster than the US military knows.

When the United States had just entered the war, German submarines had carried out a huge submarine war on the east coast, which was the first climax of German submarines, and the United States, which had just entered the war, was very clumsy in anti-submarine warfare, and had neither an escort system, nor light control, and even a Z-shaped anti-submarine route, and lost a lot of freighters in vain.

After the German occupation of the Azores, the U-boat entered a second active period, and the two sides have been engaged in a tug-of-war on the periphery of the east coast, but on the whole, the main combat mission of the German submarine is to cut off shipping in the North Atlantic, and to harass and reconnoiter the east coast and the Caribbean, although it is annoying but not uncomfortable.

The North Atlantic Strangulation War marked the third active period of the U-boat force, this time marked by the serial service of XXI-class submarines, especially during the Battle of Newfoundland, German submarines made great contributions to the German Navy, and the captured megaton freighter had a great contribution to the submarine.

The United States is well aware that Germany has put in more and more new submarines, and although it has sunk a few of them, because the wreckage of the submarine has never been fully captured or found, experts have racked their brains to figure out why this new German submarine can run so fast. Originally, I felt that the US submarine technology was not lagging behind, but after a comparison at present, it is far behind.

Admiral Kim has been angry several times about this: if the advanced submarine itself cannot be built, it is just that, and the enemy has not even figured out how the enemy works, doesn't it make people laugh out of their big teeth?

Scolding and scolding, if you can't figure it out, you can't figure it out, and there is no way to force it. Besides, the US Navy has a lot of things that it does not understand, and it is no worse than a submarine -- the Navy clearly knows that Germany and Japan have a torpedo that is particularly powerful, extremely fast, and well concealed, but so far it has not been able to fully explain its working principle. Some experts speculated that it was an oxygen-powered torpedo, but it was refuted by many more people because the United States had not tried oxygen-powered torpedoes, and all of them ended in failure.

There are super-torpedoes, super-submarines in the U.S. intelligence notification system, specifically to deal with unexplained German equipment.

As Britain entered the countdown to the armistice, the United States was about to usher in the fourth active period of U-boat attacks: Dönitz made drastic adjustments to its submarine forces, stopping the service of more than 300 VII-class and VIX-class submarines in one go, transferring some of the submarine officers and men serving on them to destroyers, some to the advanced XXI-class submarines, and even the more advanced XXIII-class (Type 23) submarines have also been successfully developed and are ready to be built in batches.

The Type 23 is an improvement on the basis of the Type 21 submarine, with a standard displacement of 2,300 tons (close to 3,000 tons when fully loaded), three diesel engines with a total of 9,000 horsepower from MAN Company, a total of 10 torpedo tubes (carrying a total of 32 torpedoes) in the front 6 and 4 in the rear, a maximum surface speed of 20.4 knots, a maximum diving speed of 19.2 knots, and a cruising range of 18,000 nautical miles in an 11-knot state.

This is not only a further improvement in indicators, but the biggest improvement is that it has begun to move closer to modern submarines -- speeding up and reducing noise.

Three 3,000 hp MAN low-speed diesel engines drive a two-shaft, five-blade tilting propeller – the most advanced propeller available. The cavitation formed when the propeller rotates rapidly is the culprit of the increased noise, so reducing the cavitation is the fundamental way to reduce the noise, German scientists have known that the odd number of blades is less likely to produce bubbles than even number of blades, and the more leaves, the smaller the bubbles, but the more the number of leaves, the greater the difficulty of processing.

Hoffman knew that the 7-blade large-tilt propeller would not have a chance to be developed until the 5-axis linkage CNC machine tool was successfully developed - the Soviet Union had not been able to make it in the past, and it was not processed until Toshiba sold them the Batumi control machine tool. Now the level of processing of German submarine propellers is deservedly the first in the world.

In addition to the improvement of the machining accuracy of the blades, the blade material was also improved, and the manganese-copper alloy was used, although it was not as good as the propellers made of modern composite materials, and in the 1944s it was considered to be well-deservedly advanced.

In addition to the propeller noise reduction, great efforts have also been made to reduce the internal noise, expanding the use of the engine base spring shock absorbing floating raft, using the expanded displacement to expand the thickness and size of the hull shell covering "Ali Berridge" rubber silencing pads, from the original 30 mm to 45 mm. The internal pipelines are also wrapped with thick sound-dampening material.

The characteristics of the remaining Type 21 continue to be retained: for example, the bow is equipped with an active and passive sonar base array, which can accurately locate enemy ships and calculate torpedo firing parameters; Thickened high-yield steel hulls allow for a depth of 400 meters; The immature T5 acoustic torpedoes were not on board, but the wire-guided torpedoes began to be put on board one after another.

After testing, the noise of the Type 23 submarine is nearly 10 decibels lower than that of the Type 21 when operating at the maximum speed when the speed is increased by 2 knots, and it can be 15 decibels lower under normal conditions. Originally, the noise level of Type 21 was unique in the world, but now it has Type 23, which is worthy of the reputation of "ocean black hole".

Of course, the Type 23 also has many problems, such as the high cost - the price of 1 Type 23 is equal to 2 Type 21 is equal to 4 Type VII submarines, the construction period is long, the construction is difficult and so on, but both the Navy and Hoffman are very satisfied with this, because this is the tiger king of the submarine world! The Ministry of Armaments approved a budget for the construction of 12 articles, which required that all of them be completed by June 1945.

In Hoffman's eyes, the Type 23 submarine has even more potential -- a foundation for the next step in upgrading to a nuclear attack submarine.

As for the design based on the I-400, with a full load displacement of 7,500 tons, a single cost of 100 million marks, and a behemoth that can be deployed globally, the XXX-class (Type 30) ballistic missile submarine is also under construction, and it is expected that the first ship will be completed in March 1945, which is the real super submarine!

Dönitz, who had more and more sharp weapons at hand, began to send a large number of submarines to the Caribbean Sea to carry out tasks according to the change of situation, and the Azores, the Canary Islands, and Cape Verde all became submarine supply bases, among which the Azores had the best conditions, but they were far from the battlefield, and Cape Verde was closest to the front line, but the conditions were the worst. However, for the XXI submarine with a range of more than 15,000 nautical miles, this distance is drizzle. The US Navy could never have dreamed that the XXI-class submarines active along the East Coast, the Caribbean, and the coast of Central America were not at all more than 20 as they expected, but nearly 30!

Soon this number will rise to 50, after the end of the Icelandic campaign, the strategic focus of the German army will shift, the North Atlantic direction to undertake the task of the submarine will continue to expand, and all of them are the latest XXI class submarines, Dönitz will send more than eighty percent of the new submarines to the area - the current construction rate of the XXI class is 12 per month, with the reduction of the scale of army equipment production, it is expected to increase to 16 ships per month from August, of which Type 23 will account for a quarter of the share.

Hewitt's estimate was correct, and the submarine he encountered was a Type 23 submarine that had only recently been commissioned and had only two in the U-boat force.

The new XXIII-class submarine had already found its target, but when the cautious captain found himself in a large fleet, he immediately changed his mind, relying on its fast underwater speed to escape, and then waited for night to send a telegram to Kranc stationed in the harbor, and at the same time to the command center in the Azores, ready to mobilize the wolves to attack.

The sonar of a U.S. Fletcher-class destroyer on duty on the periphery vaguely heard an unusual sound, but by the time he reacted, the sound was far away, and he could only tell Hewitt the news of the suspected contact with the submarine, and then the latter reported it as it was.

The Type 23 submarine is almost impossible to attack, because the destroyer must rely on sonar positioning to effectively drop depth charges for attack, but the Type 23 is fast, and if the destroyer or anti-submarine ship wants to keep up with this speed, the sonar soldier can no longer distinguish the noise of the ship from the noise of the enemy ship, and there is no way to track the attack; If you slow down, you will immediately let your opponent slip away, so unless you are caught by a surface ship just when you are on the surface. But even then, the two need to be close enough to each other.

The U.S. military used radar to find a German submarine 30 kilometers away with a snorkel to recharge, and by the time the two destroyers arrived at the scene, the submarine had already dived and fled, and the unbelieving destroyers threw all the hedgehog bullets to the place they thought was suspicious, but found nothing.

This feeling of not being able to hit even though you know there is a submarine is too bad, as is the case with the Type 21 submarine, and the Type 23 submarine, which is faster, has stronger stealth capabilities, and has a lower noise level, is even more terrifying.

In the face of the "black hole of the ocean", traditional anti-submarine has come to an end......