The mighty and majestic steel dragon did not bring a sense of stability to Admiral Nimitz, who was on the bridge of the USS Franklin aircraft carrier. His brows were still furious and unstable.

A few hours ago, he received two telegrams: the first one was sent by Lieutenant General Hewitt, the commander of the Transportation Force, informing the suspected discovery of German submarines.

Nimitz knew that Hewitt was a very cautious general, and he said that there should be more than 70%. During this period, German submarine activities have been in the Caribbean, Central American waters and the East Coast, and Hewitt's judgment is estimated to be 90% likely.

The Navy has established an Anti-Submarine Security Command, and it is expected that there will be at least 20 German submarines in this sea area. Not only will the number gradually increase, but the new submarines with advanced performance are faster than the US military's perception.

When the United States just joined the war, German submarines had a massive submarine war on the east coast. This was the first climax of German submarines. The United States, who had just joined the war, was very clumsy in anti-submarines. It had neither escort system nor light control, and even had a z-shaped anti-submarine route, which lost many cargo ships in vain. As the US military strengthened its anti-submarine and escort system and focused on its own concealment, the unnecessary losses gradually decreased. The German submarine captain who could not get any oil and water turned the center of gravity back to the direction of the North Atlantic.

After Germany occupied Azores, U-boats entered the second active period, and the two sides had been launching a tug-of-war on the outside of the East Coast. However, overall, the main combat mission of German submarines was to cut off the North Atlantic shipping, and to harass and reconnaissance on the East Coast and the Caribbean. Although it was annoying, it was not uncomfortable.

The North Atlantic strangle war marked the third active period of the U-boat troops. This time, it was marked by the mass service of the xxi-class submarines. Especially during the Battle of Newfoundland, German submarines made great contributions to the German Navy, and the seized million-ton cargo ships were a great contribution to the submarines.

The United States clearly knows that Germany has invested in new submarines, and the number is increasing. Although several have been sunk, the experts have racked their brains to find out why this new German submarine can run so fast. I feel that the American submarine technology is not behind, but now after comparison, it is far inferior.

General Jin has fired several times for this: it would be fine if the advanced submarines cannot be built by themselves, but they have not even figured out the working principle of the enemy. Wouldn't it make people laugh?

No matter how much you scold, you can't figure it out, and you can't figure it out. Besides, there is too much stuff the US Navy can't figure out, and it's not like a submarine. The Navy clearly knows that Germany and Japan have a torpedo with extremely powerful power, very fast speed and good concealment, but so far, it still cannot fully explain its working principle. Some experts speculate that it is an oxygen-powered torpedo, but more people refute it because the United States has not tried oxygen torpedoes, and all ended in failure.

In the US intelligence notification system, there is the claim of super torpedo and super submarine, which is specifically used to deal with unexplained German equipment.

As Britain enters the countdown to the armistice, the United States is about to usher in the fourth active period of U-boat attack: Denitz made drastic adjustments to the submarine force, and stopped more than 300 Vii-class and Vix-class submarines in one go, and some of the submarine officers and soldiers in service were transferred to destroyers and some of them were transferred to advanced Xxi-class submarines. Even the more advanced Xxiii-class (type 23) submarines have been successfully developed and are ready to be built in batches.

The 23 model is improved on the basis of the 21 submarine. The standard displacement is expanded to 2,300 tons (nearly 3,000 tons at full load). It uses three diesel engines of Man Company with a total of 9,000 horsepower. It has a total of 10 torpedo launchers with front 6 and rear 4 (carrying 32 torpedoes in total). The maximum surface speed is 20.4 knots, a maximum submarine speed of 19.2 knots, and a cruising capacity of 18,000 nautical miles at 11 knots.

This is not just a further improvement in the indicators, the biggest improvement is to start moving closer to modern submarines to speed up and reduce noise.

Three 3,000 horsepower low-speed diesel engines of Man Company drive 2-axis 5-blade inclined propellers, which are the most advanced propellers under the existing technical conditions. The cavitation formed when the propeller rotates quickly is the culprit for increasing noise, so reducing cavitation is the fundamental way to reduce noise. German scientists have known that odd blades are less likely to produce bubbles than even blades. Moreover, the more leaves, the smaller the bubbles, but the more leaves, the more difficult it is to process.

Hoffman knew that the 7-blade large roll propeller had to wait until the 5-axis linkage CNC machine tool was successfully developed before he had the opportunity to create it. In history, the Soviet Union could not do it until Toshiba sold it to them to the Batong-controlled machine tool. Now the processing level of German submarine propellers is well-deserved as the world's number one.

In addition to improving the blade processing accuracy, the blade material has also been improved, using manganese-copper alloy. Although it is not as good as propellers made of modern composite materials, it was well-deservedly high-end in the 1944.

In addition to propeller noise reduction, a lot of effort was put into operation in the internal noise reduction, expanding the use of engine base spring shock-absorbing floating rafts, using the expanded displacement to expand the thickness and size of the hull shell covering the "Aliberic" rubber silence tiles, increasing from the original 30mm to 45mm. The internal pipelines are also wrapped with thick silence materials.

The characteristics of the remaining 21 types continue to be retained: if the boat head is equipped with an active passive sonar matrix, the enemy ship can be accurately positioned and torpedo shooting parameters can be calculated; the thickened high yield steel boat hull makes the diving depth reach 400 meters; the immature T5 sound guided torpedoes have not been boarded, but the line guided torpedoes have begun to board the ship one after another.

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

Of course, the 23 type also has many problems, such as the high cost of 1 type 23 is equivalent to 2 type 21 is equivalent to 4 Vii submarines, the construction period is long, the construction difficulty is difficult, etc. However, both the navy and Hoffman are very satisfied with this, because this is the tiger king in the submarine world! The Ministry of Military Affairs approved the budget for 12 construction items, requiring that all construction must be completed by June 1945.

In Hoffman's eyes, the Type 23 submarine has greater potential to lay the foundation for the next step of upgrading to a nuclear attack submarine.

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

Denitz, who had increasingly sharp weapons at hand, began to send submarines to the Caribbean to perform missions in large quantities according to the change of the situation. Azores, Canary Islands, and Cape Verde have become submarine supply bases. Among them, Azores are the best conditions, but they are far away from the battlefield. Cape Verde is closest to the front line, but the conditions are the worst. However, for the xxi submarines with a range of more than 15,000 nautical miles, this distance is drizzling. The US Navy never dreamed that the active xxi-class submarines on the East Coast, the Caribbean, and the coastal areas of Central America were not the more than 20 they expected, but nearly 30!

Soon this number will rise to 50. After the Battle of Iceland, the German army's strategic focus will shift. Submarines that undertake missions in the North Atlantic will continue to expand, and they are all the latest Xxi-class submarines. Denitz will send more than 80% of the new submarines to the region. The current construction speed of the xxi-class is 12 per month. As the scale of army equipment production decreases, it is expected to increase to 16 ships/month from August, of which 23 types will account for a quarter of the share.

Hewitt's estimate is correct. The submarine he encountered was in service, with only two Type 23 submarines in the U-boat troops.

The new xxiii-class submarine had already found its target, but when the cautious captain found himself in a huge fleet, he immediately changed his mind and fled with his fast underwater speed. Then he waited for the night to come and sent the telegram to Crank, stationed in the port, and at the same time to the command center on Azore, preparing to mobilize the wolves to attack.

A US Fletcher-class destroyer sonar soldier on duty outside could vaguely hear an unusual sound, but when he reacted, the sound was gone, so he could only tell Hewitt about the suspected contact of the submarine, and then the latter reported it intact.

Type 23 submarines are almost impossible to attack because destroyers must rely on sonar positioning to effectively throw deep-water bombs to attack. However, Type 23 is very fast. If the destroyer or anti-submarine ship wants to keep up with this speed, the sonar soldiers can no longer distinguish the noise of the ship from the enemy ship, so there is no question of tracking attack; if the speed is slowed down, the opponent will immediately slip away, so unless they are caught by the surface ship when they are floating. But even so, the distance between the two must be close enough.

The US military once used radar to find German submarines charging with exposed snorkels 30 kilometers away. When the two destroyers arrived at the scene with great momentum, the submarine had already dived and fled. The destroyer who did not believe in evil threw all the hedgehog bombs to the places they thought were suspicious, but found nothing.

This feeling of making people know that there is a submarine but cannot hit it is really bad. This is the case with the Type 21 submarine, which is faster, has stronger stealth ability and has lower noise levels, is even more terrifying.

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