Chapter 491 Silencer Tiles

In the battle between submarines and surface ships, submarines are always at a disadvantage. For submarines, constantly improving their silent performance is the basis for their continued existence. When the underwater noise is comparable to the background noise of the ocean, it becomes extremely difficult for surface warships to detect underwater submarines.

It is from this perspective that active sonar will gradually develop in later generations, and even active towed body sonar will appear, all to counter new types of submarines.

The use of active sonar requires a certain price. War is fair, and the greater the price, the greater the benefit. Turning on active sonar is a dangerous move that puts oneself in danger of death. After all, submarines hide in the dark, and turning on active sonar can easily be discovered by submarines. On the battlefield, whoever turns on active sonar will be attacked first!

Therefore, if it is really a battle, the ships that use active sonar are relatively low-value frigates. If they use active sonar, they are actually ready to fight to the death. Ten thousand ton warships, or even tens of thousands of ton aircraft carriers, will not take this risk. This is a life-and-death battle.

But now, it doesn't matter. Up to now, the United States and the Soviet Union have not really torn their faces apart and staged the Third World War. In this case, the two sides are still confronting each other in the style of the Cold War, with customary rules. For example, if a submarine enters the range of their fleet, it will definitely be beaten. As long as the other side surfaces, the confrontation is over.

Turning on the active sonar is like turning on countless flashlights to illuminate the underwater world. I don’t believe that we can’t find you!

The Americans are crazy! When the sonar operator discovered that the US fleet had turned on the active sonar, Nilgayev also began to respond and dived!

Diving? Is this a way to deal with active sonar? Of course not! The detection range of active sonar can even exceed 20 kilometers, and the depth of diving is limited to a few hundred meters.

But now, we can use diving to deal with American detection!

Emergency dive! Following Nirgeyev's order, the submarine's horizontal rudder began to rotate drastically. At the same time, all the submarine soldiers who were not on duty quickly ran from their positions to the torpedo compartment in the front!

The bow began to move downward rapidly, and the huge submarine tilted its hull and continued to dive!

The hull stirred up the water, which might have caused additional noise, but now, there was no time to worry about that!

At this moment, several sonar waves hit the hull of the huge 949-class submarine.

If it is an ordinary submarine, when it is hit by active sonar waves, the hull will vibrate, and the cavity effect will amplify the sound. The submarine soldiers inside can clearly hear this terrible sound. For them, the detection of active sonar means the arrival of a torpedo at the next moment.

But now, the active sonar waves hit the hull and first came into contact with the outer shell of the submarine, but before they touched the surface, they encountered something soft.

Silencer tiles!

150 mm thick anechoic tiles made of styrene-butadiene rubber are laid on the hull of the submarine. There is a complex acoustic structure inside. When active sonar waves come over, the anechoic tiles absorb most of them!

The Soviet Union has been using double-hull submarines. The inner and outer hulls of this type of submarine are covered with sound-absorbing tiles. The outer sound-absorbing tiles are mainly used to deal with active sonar, while the inner sound-absorbing tiles are mainly used to reduce noise for themselves!

Moreover, the sonar waves coming this time were not the sonar waves from that abnormal aircraft carrier, but just the sonar waves from ordinary destroyers and frigates. After being absorbed, the sonar waves reflected back were quite small!

The personnel inside the submarine could hardly hear the sonar waves from the outer layer. Only the sonar operator quickly took off his headphones, covered his ears, and cursed quietly: "Damn Americans!"

The principle of sonar is to amplify sound signals. At this time, the amplified active sonar signal makes the sonar operator's ears extremely painful.

Dive, keep diving! As if it had acquired an iron shield, the 949-class submarine withstood several sonar waves and finally dived into the water at a depth of 150 meters.

"Balance the boat, calibrate the course, and keep moving forward," said Nirgeyev.

The sonar operator put on his headphones again. The noisy active sonar sounds had all disappeared. Except for the unique gurgling sound of the ocean background noise, there was nothing else!

"We have successfully entered the density jump layer." The sonar operator reported.

Density jump layer!

There is salt in seawater. The density of seawater varies with the amount of salt. Generally speaking, the density suddenly increases with increasing depth. The water layer where the density of seawater suddenly increases in the vertical direction is called a density jump layer.

This is a dividing line. The density of seawater is very different between the surface and deep layers. The seawater with low density will gather on the seawater with high density, making the upper layer light and the lower layer heavy, so that the seawater is distributed in layers. A barrier is naturally formed between the upper and lower layers, called the density jump layer. The depth is different. In the ocean, it may be more than a thousand meters, while in the near sea, it may be more than a hundred meters deep.

These hydrological conditions can only be known through advance surveys. Major submarine powers all have oceanographic survey ships, and under the name of survey, they are actually preparing for submarine operations.

Density jumps are of great significance to submarine navigation. Because this jump will refract the propagation of sound waves! In other words, the sound waves of active sonar emitted by the US warships on the surface at this time are all blocked by the jump! Submarines can avoid being discovered by hiding under the jump!

Moreover, the thermocline is relatively stable, and submarines know that they can stay on it and flow with the seawater, saving fuel. Therefore, the density thermocline can be said to be a "liquid seabed".

In addition to density jump layers, various complex hydrological environments such as thermocline, halocline, and soniccline can also be utilized underwater. Here, the density jump layer is the most suitable.

Stay safe and sound underwater, and you won’t be afraid of anything!

"Full speed ahead." Nirgeyev gave the order. Since they had entered the density jump layer, the active sonar waves detected from above could not come down, and the noise from their own submarines could not be transmitted upwards. Therefore, it was most important to take advantage of this opportunity to leave here quickly. The previous voyage had proved that the US aircraft carrier formation could not effectively detect their own nuclear submarines. If a war really broke out, the 949 class would become a stealth killer!