Chapter 970 Nimitz's Counterattack (3)
The mighty steel dragon did not bring a sense of security to Admiral Nimitz, who was sitting on the bridge of the USS Franklin. His brows were still furrowed and he was uneasy.
A few hours ago, he received two telegrams in succession: the first one was from Vice Admiral Hewitt, the commander of the transport force, reporting the suspected discovery of a German submarine.
Nimitz knew that Hewitt was a very cautious general. He said that there should be a probability of more than 70%. During this period, there have been German submarines in the Caribbean Sea, the Central American waters and the East Coast. Hewitt's judgment estimated that there was a 90% possibility.
The Navy has established a separate anti-submarine security command. It is expected that there are at least 20 German submarines in this sea area. Not only are the number gradually increasing, but they are also new submarines with more advanced performance - the speed is faster than the US military's cognition.
When the United States just joined the war, German submarines once conducted a massive submarine war on the East Coast. This was the first climax of German submarines. The United States, which had just joined the war, was very clumsy in anti-submarine warfare. It had no escort system, no blackout, and even did not take the Z-shaped anti-submarine route, and lost a lot of cargo ships in vain. As the US military strengthened its anti-submarine and escort systems and focused on its own concealment, the unnecessary losses gradually decreased. The German submarine captains who could not make money turned their focus back to the North Atlantic.
After Germany occupied the Azores, U-boats entered the second active period. The two sides had been fighting a tug-of-war on the periphery of the East Coast, but overall, the main combat mission of German submarines was to cut off North Atlantic shipping. They mainly harassed and reconnaissance the East Coast and the Caribbean, which was annoying but not uncomfortable.
The North Atlantic stranglehold marked the entry of the U-boat force into the third active period. This time, the XXI-class submarines were put into service in batches. Especially during the Newfoundland Campaign, German submarines made great contributions to the German Navy. The million-ton cargo ships captured were contributed by submarines.
The United States clearly knows that Germany has invested in new submarines, and the number is increasing. Although several submarines have been sunk, experts have racked their brains to figure out why this new German submarine can run so fast because they have never captured or found the wreckage of the submarine. Originally, I felt that the American submarine technology was not backward, but now it is far behind after comparison.
Admiral Jin has been angry several times for this: it’s okay that we can’t build advanced submarines, but we don’t even understand the working principle of the enemy. Isn’t it ridiculous?
No matter how much you scold, you can’t figure it out. There is nothing you can do no matter how much you force it. Besides, the US Navy has a lot of things that it can’t figure out, and it’s not bad for submarines. The Navy clearly knows that Germany and Japan have a torpedo that is extremely powerful, extremely fast, and has good concealment, but so far, it still cannot fully explain its working principle. Some experts speculated that it was an oxygen-powered torpedo, but it was refuted by more people-because the United States has tried oxygen torpedoes, and all of them ended in failure.
In the US intelligence reporting system, there are super torpedoes and super submarines, which are specifically used to deal with inexplicable 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 the submarine force, stopping the service of more than 300 Class VII and Class XIV submarines in one go, transferring some of the submarine officers and soldiers serving on them to destroyers, and some to advanced Class XXI submarines. Even the more advanced Class XXIII (Type 23) submarines have been successfully developed and are ready to be built in batches.
The Type 23 is an improvement on the Type 21 submarine. The standard displacement has been expanded to 2,300 tons (close to 3,000 tons when fully loaded). It uses 3 MAN diesel engines with a total of 9,000 horsepower. It has a total of 10 torpedo tubes (carrying a total of 28 torpedoes), a maximum surface speed of 19.7 knots, a maximum submerged speed of 18.4 knots, and a cruising range of 16,000 nautical miles at 11 knots.
This is not just a further improvement in indicators. The biggest improvement is that it has begun to move closer to modern submarines - speeding up and reducing noise.
Three 3,000-horsepower MAN low-speed diesel engines drive two-axis, five-blade tilt propellers, which are the most advanced propellers under current technical conditions. The cavitation formed when the propeller rotates rapidly is the culprit for the increased noise, so reducing cavitation is the fundamental way to reduce noise. German scientists have known that odd-numbered blades are less likely to produce bubbles than even-numbered blades, and the more blades there are, the smaller the bubbles are, but the more blades there are, the more difficult it is to process.
Hoffman knew that the 7-blade large tilt propeller would have to wait until the 5-axis linkage CNC machine tool was successfully developed before it could be made - in history, the Soviet Union had never been able to make it until Toshiba sold them the Batumi controlled machine tool before processing it. Now the processing level of German submarine propellers is well-deserved to be the world's first.
In addition to the improvement of 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-deserved in 1944.
In addition to reducing propeller noise, a lot of effort has also been put into reducing internal noise, expanding the use of spring shock-absorbing rafts on the engine base, and using the increased displacement to increase the thickness and size of the "Aliberich" rubber sound-absorbing tiles covering the hull from the original 30mm to 45mm. The internal pipelines are also wrapped with thick sound-absorbing materials.
The remaining features of the Type 21 are retained: for example, the active and passive sonar arrays are equipped at the bow, which can accurately locate enemy ships and calculate torpedo firing parameters; the thickened high-yield steel hull allows the diving depth to reach 280 meters; the immature T5 acoustic-guided torpedoes are not on board, but wire-guided torpedoes are gradually being installed.
After testing, the Type 23 submarine has a noise level that is nearly 10 decibels lower than the Type 21 when running at the highest speed, and can be 15 decibels lower under normal conditions. The Type 21 has already been the world's most savvy in terms of noise level, and now with the Type 23, it is more worthy of the reputation of "ocean black hole".
Of course, the Type 23 also has many problems, such as high cost - one Type 23 is equal to the price of two Type 21s or four Type VII submarines, long construction period, difficult construction and other shortcomings, but both the Navy and Hoffman are very satisfied with it, because this is the Tiger King in the submarine world! The Armaments Department approved the budget for the construction of 12 submarines, requiring that all of them must be completed by June 1945.
In Hoffman's eyes, the Type 23 submarine has greater potential - it can lay the foundation for the next upgrade to a nuclear attack submarine.
As for the XXX-class (Type 30) ballistic missile submarine, which is designed based on the I-400, has a full load displacement of 7,500 tons, a single cost of 100 million marks, and can be deployed globally, it is also under intensive construction. It is expected that the first ship will be completed in March 1945. This is a real super submarine!
Dönitz, who has more and more powerful weapons at hand, began to send a large number of submarines to the Caribbean to perform missions according to the changes in the situation. The Azores, the Canary Islands, and Cape Verde have all become submarine supply bases. Among them, the Azores has the best conditions, but it is far away from the battlefield. Cape Verde is closest to the front line, but the conditions are the worst. However, for the XXI submarine with a range of more than 15,000 nautical miles, this distance is a drizzle. The U.S. Navy could not have dreamed that the number of XXI-class submarines active along the East Coast, the Caribbean Sea, and the coast of Central America was not the 20 or so they expected, but nearly 30!
Soon this number will rise to 50. After the Icelandic Campaign, the German strategic focus will shift, and the submarines responsible for missions in the North Atlantic will continue to expand, and they will all be the most advanced XXI-class submarines. Dönitz 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 per month from August, of which the Type 23 will account for a quarter.
Hewitt's estimate was correct. The submarine he encountered was the Type 23 submarine that had just been in service and there were only two in the U-boat force.
This new XXIII-class submarine had originally identified its target, but when the cautious captain found himself in a large fleet, he immediately changed his mind and fled with his fast underwater speed. Then he waited for nightfall to send a telegram to Crank stationed in the port, and at the same time sent a telegram to the command center on the Azores, preparing to mobilize the wolf pack to attack.
The sonar operator of a US Fletcher-class destroyer on duty outside vaguely heard an unusual sound, but when he reacted, the sound had gone far away. He could only tell Hewitt about the suspected contact with the submarine, and the latter reported it intact.
The Type 23 submarine is almost invulnerable, because the destroyer must rely on sonar positioning to effectively throw depth charges for attack, but the Type 23 is so fast that if the destroyer or anti-submarine ship wants to keep up with this speed, the sonar operator can no longer distinguish the noise of the ship from the enemy ship, so there is no tracking attack; if the speed is slowed down, the opponent will slip away immediately, so unless it is caught by the surface ship when it just surfaces. But even so, the distance between the two must be close enough.
The US military once used radar to detect a German submarine with a snorkel exposed for charging 30 kilometers away. When two destroyers rushed to the scene, the submarine had already dived and escaped. The destroyers, who did not believe in evil, threw all the hedgehog bombs at the place they thought was suspicious, but found nothing.
This feeling of knowing that there is a submarine but not being able to hit it is really bad. The Type 21 submarine is like this, and the Type 23 submarine with faster speed, stronger stealth ability and lower noise level is even more terrifying.
In front of the "ocean black hole", traditional anti-submarine has come to an end...