Although the JPJ freighter was not visible in the telescope, a telegram had just been sent from the PJP. As if he had some sixth sense, Zheng Xuechang always felt that danger was approaching, and immediately ordered the Baxia to move forward at full speed and approach the PJP.

When the PJP was seen in the telescope, it was only a dozen nautical miles away. At this moment, a sudden change occurred, and I saw a fire shining on the sea, followed by a huge explosion.

Zheng Xuechang's heart suddenly contracted, holding the telescope in his hand, and his eyes were almost deep into the rubber arc of the telescope. When I saw the situation on the sea, I didn't know whether I was relaxed or more nervous.

The PJP was not bombed. There is no need to guess, it is that there was a battle between the Pixiu and the submarine of the Yuejun. But whether the Pixiu was bombed or the military submarine was bombed, Zheng Xuechang did not know.

Without Zheng Xuechang's order, the Baxia had already accelerated again and galloped towards the sea area where the accident occurred.

This was the first encounter between the Naval Resistance Army and a submarine of the Japanese Army.

The Pixiu has been covering the supply ship PJP since the port, and Ren Tianyang has a hunch that there must be military submarines in the surrounding waters.

So Pixiu No. 1 has always been in a state of combat readiness. The sonar soldiers searched for sounds around them at all times.

The sonar on the Pixiu 1 has now been modified. Three active sonars have been installed, and passive sonar can now be further improved. The two earphones of the earphone were transformed into two channels by Li Guang, one channel is the same as before, and the other channel is mechanically filtered and amplified.

The audiophones (passive sonar) purchased from Germany are really not advanced in Li Guang's eyes. At the beginning, Li Guang regarded this thing as high-tech, but as his understanding deepened, Li Guang found that this thing was mysterious, but it was actually the earpiece of the telephone, but the structure was different.

The walkie-talkie on the submarine's hull contains small boxes filled with carbon particles, and in front of it are thin duralumin alloy vibrating plates. The vibrating plate vibrates according to the voice vibration, vibrates the carbon particles, and the carbon particles conduct current, and with the degree of contact of the particles, the resistance changes, and the voice current is generated. After receiving the voice current of the other party, the receiver generates a magnetic force caused by the voice current on the coil, vibrates the iron vibrating plate, and emits a sound.

After learning the principle of the earpiece, Li Guang scolded the Germans for cheating his father, and dozens of microphones dared to pay a sky-high price. But this is the high technology of this era.

As we all know, the size of the sound is actually the size of the voice, and the sharpness and depth of the sound is the frequency of the sound wave.

In order to make the earpiece listen farther, Li Guang easily modified the vibration plate through mechanical methods, so that an earpiece can only receive tiny sound signals, and then added a first-stage amplification circuit, which was named Weiyin Audiophone by Li Guang. As a result, the listening system is now binaural, and the microphonic listening device can now easily grasp the sound of the propeller within 10 nautical miles.

However, the murmur in the sea is quite complex, and it takes considerable experience to distinguish the sound of a propeller.

In this way, all the sonar soldiers of the Naval Resistance Army have been improved to the previous hearing level of Ji Kelian, and even surpassed. That's the power of technology.

This small renovation was very inconspicuous, costing less than $200 for a submarine, but it was kept secret until the end of the Anti-Japanese War, and made great contributions to the Naval Resistance Army. Many scientific and technological inventions do not exist with technical difficulties, but conceptual innovations.

The Pixiu No. 1 submarine was discovered at a distance of 10 nautical miles. Not one, but two, with the sonar soldier's report, Ren Tianyang's eyes lit up.

In the past few months, Ren Tianyang has been busy building submarines in the dock all day long, and Ji Keliang took the Pixiu No. 1 to the sea twice to sink more than 15 merchant ships, and even created a miracle, the submarine captured a 5,000-ton oil tanker.

Ren Tianyang is envious, jealous and hateful. And now an unprecedented historical opportunity for the naval resistance army is in front of him.

Ren Tianyang immediately ordered Pixiu No. 1 to switch to electric mode.

Then Pixiu No. 1 made a detour forward. The motor power on the Pixiu is large enough that it can reach 16.5 knots even in a fully submersible state, which is much faster than the PJP.

When the Pixiu approached two nautical miles from the military submarine, Ren Tianyang ordered to slow down and change to a quiet state to sail.

At this time, the Pixiu was like a ghost in the sea, silently approaching the military submarine.

At one nautical mile, Pixiu 1 slowed down again, reducing its speed to three knots.

Now is not the time to leak active sonar, the Pixiu is only relying on passive sonar to quietly approach the submarine.

Now sonar crews have confirmed that two military submarines are lined up on both sides of the channel. And the PJP is also heading.

For the Pixiu, the best way is to kill the two military submarines together. But this is obviously impossible, and the distance between the two military submarines is at least three or four kilometers. It is difficult for the Pixiu to attack at the same time.

There is no way to notify Huang Zhonghua on the PJP number. Ren Tianyang decided to strike first and kill a military submarine to give Huang Zhonghua a wake-up call.

The submarine model is complex, and it is simply divided into three types, the first is a first-class submarine, which is generally a large submarine, collectively known as the I-type. The second type is a second-class submarine, which is a medium-sized submarine and is collectively known as the Lu type. The third type is a small submarine, known as a wave type.

Most of the wave types are hundred-ton gadgets, and the largest ones are no more than five or six hundred tons. It is generally used for training or offshore patrols. Most of the submarines used on the battlefield are I-type submarines and Lu-type submarines.

From the classification of submarines, we can see the speed of development of submarines between World War I and World War II, and in less than 20 years, more than a dozen models of medium and large submarines were developed. There are so many models, but the total is not much. As for submarines, a new gadget that has only appeared for a few decades, he said that he is developing while exploring, just like other countries.

In World War II, the role of submarines was not brilliant compared with Germany, but it does not mean that the submarine technology of this is poor. The reason why the results of the battle were not brilliant was related to the operational thinking of the navy. In fact, in the year 39, the submarines of the book were no worse than the Germans in terms of quantity and quality.

Now Ren Tianyang is facing the relatively old Haida Type 1 submarine and Haida Type 2 submarine. This is the first large submarine of the Navy, and there is only one of each model. Among them, the Haida 1 type is the Yi 51 submarine, and the Haida 2 type is the Yi 58 submarine.

In fact, the two submarines are about the same, just like the relationship between Pixiu 1 and Pixiu 2. The basic parameters of both submarines, such as displacement and power, did not differ much. If you just look at the data, it is no worse than Pixiu.

Even more powerful in some figures, the diesel engines of these two submarines are more powerful than the Pixiu, one with 5,800 horsepower and the other with 6,800 horsepower. The two diesel engines of the Pixiu have a total power of 5,000 horsepower.

The main armament of the two submarines was also torpedoes, and like the Pixiu, they were all eight torpedo launchers.

In terms of displacement, both ships are more than 2,400 tons underwater and 1,400 tons on the surface. It's on par with Pixiu.

The Pixiu installed two 88mm deck guns was powerful enough, but Xiao Yueben's perverted pursuit of firepower actually installed a 120mm caliber, 45 times the diameter of the naval gun and a 76mm cannon on the deck.

A simple comparison of the data does not illustrate the difference in combat effectiveness. These two submarines were both products of the pre-1925 period, but they are now aging and do not look good, and they are also old ships that are about to be dismantled in the navy.

But until there is no new submarine replenishment, this is still the main submarine of the Fifth Fleet. After all, it is big and has a strong battery life.

Last time, the Pixiu sank three warships of the Fifth Fleet in one fell swoop, and as a result, there were only two gunboats left in the Fifth Fleet Onishi Brigade on Weizhou Island.

However, these two submarines have problems at both ends in three days, and it is good to be able to go to sea for ten days and eight days a month, and sometimes warships have to be towed back to the port for repairs. Fortunately, it is a mission in the Gulf of Tonkin and a question of whether it can be returned if it is placed in the South China Sea or the Pacific Ocean.

These two submarines are now busy keeping an eye on the PJP. It was not discovered at all that the Pixiu was approaching the battlefield.

These two military submarines have a huge sound when the diesel engine is running, and the sound insulation effect is extremely poor. More than ten nautical miles were detected by the Pixiu. The little devil still thought he was ingenious, and only five nautical miles away from the JPJ began to sail at periscope depth.

Where would he have thought that the PJP would be an ordinary merchant ship. Although there is no sonar and radar, there are four telescopes with a diameter of 12 centimeters on board, and there are even more telescopes with small apertures, and the largest telescope is the 15-centimeter German Zeiss telescope. Not to mention five nautical miles, even ten nautical miles cannot escape Huang Zhonghua's eyes. The tall conning tower of this submarine has long been in the eyes of the Maritime Resistance Army.

Although the weather in Beibu Gulf is not very good today, how bad can the weather be when planes can take off? The military submarine that underestimated the PJP was destined to be taught a lesson.

It is said that the submarines of the army are far inferior to the naval resistance forces in this regard. Li Guang's guiding ideology is to attach importance to the enemy strategically and tactically, and to regard the enemy as a stronger opponent than himself. This kind of thinking has now penetrated into all the tactical thinking of the naval resistance army, and every time it is a lion fighting a rabbit, with all his might.

But the devils just treated the supply ship PJP as an ordinary merchant ship, and they were extremely careless, and they did not even guard against warships and submarines at all.

The 75mm field guns on the PJP lacked range and did not fire, but the gunners were already in good standby.

Huang Zhonghua couldn't see the Baxia, but he had already notified the Baxia as soon as possible. At this moment, the Baxia has already chopped the waves and sailed towards the battlefield. Huang Zhonghua would not be stupid enough to hit the muzzle of the devil's submarine, and immediately ordered the PJP to start turning.

At this time, the Pixiu submarine had already moved to the side of a submarine less than 300 meters, and the four torpedoes were like arrows from the string, directly attacking the submarine of the Yuejun army.

This is the first time in actual combat that active sonar has been used to determine the position of the devil submarine. This tactic is the first of its kind in the world, relying entirely on sonar and not aiming at all with periscopes. In order to ensure that the submarine could be destroyed at one time, Ren Tianyang fired four torpedoes in a fan-shaped manner.

The sound of the explosion a minute later proved that this tactic of relying only on sonar shooting under water needs to be improved, and at such a close distance, the opponent is almost at a very low speed, only one torpedo. Three torpedoes missed.

From the use of active sonar, to the calculation of the position of the submarine, to the launch of the torpedo, it took nearly two minutes in total. But it is obvious that the estimated sonar level of the military submarine is extremely low, and it did not pay attention to the sound waves at all, or there was no one at the post at all, and the devil's submarine did not react as it should at all.

The explosion of the torpedo hitting the submarine was extremely spectacular, and the huge explosion force stirred up a column of water tens of meters high on the sea surface, and it was like a rain within one or two kilometers, and the sound was extremely terrifying. The explosion was deafening for tens of miles.

This kind of powerful explosion was obviously not the momentum caused by a torpedo sent by the Pixiu, but definitely detonated the torpedo on the submarine of the Yue Army.

The army did not have time to react at all, and a submarine of more than 2,000 tons had become scrap metal, which quickly sank to the bottom of the sea, and rotted along with the sludge.