The submarine project of the Tang Empire has been in a state of difficult birth, on the one hand, the Navy has achieved great military success in aircraft carrier battle groups, which has made the status of submarines decline. On the other hand, the requirements of the General Administration of Equipment of the Tang Army for submarines are too high, which makes submarine experts have to spend a lot of energy in research and development.

The culprit of all this is actually Zhang Meng, although he has corrected his mistake a few years ago, but what he said is a holy decree, even if he subsequently asked the General Equipment Administration to lower the standards of submarine design and development, but in practice, that invisible influence still exists.

According to Zhang Meng's initial requirements, he hoped that the submarines of the Tang Army would have enough diving time and enough safe diving depth to avoid the pursuit of enemy ships, and that there should be enough silent effect to prevent detection by the enemy's underwater listening equipment.

The general standard for submarines in the thirties was a maximum depth of 80 meters, and the maximum diving time would not exceed 24 hours, which was still at a minimum speed of 3 knots, and a maximum of two hours if it was cruising at about 14 knots. The mute effect is almost impossible, because it is very difficult for any submarine to not be heard by the enemy unless it does not move.

With the continuous progress of the material processing technology of the Tang Empire, the industrialization of rare metal refining provides a large number of high-strength, pressure-resistant and corrosion-resistant alloy special steels for the Datang military industry, and submarine experts use them in the manufacture of submarines, which finally enables the submarines of the Tang Army to withstand the water pressure of 400 meters for navigation, solving the problem of maximum safe diving depth.

The issue of diving time is far more complex and difficult than the maximum safe dive depth. The submarine experts of the Tang Army had to ask scientists and scholars in other specialized fields for help to use air regeneration jishu in the submarine to improve the battery storage capacity. In-depth research on improving the efficiency of electric motors in order to achieve a huge increase in maximum dive time.

With the success of the National Academy of Sciences' Tesla Shiyan orbital kinetic energy gun Jishu, the high-capacity battery designed by Tesla to provide instantaneous electrical energy for the electromagnetic cannon Jishu, after improved design, a lead-acid battery pack with higher performance was developed, plus a high-efficiency motor that has been improved many times, and finally installed on the submarine, so that the submarine can dive for a month at a speed of 3 knots.

But another key problem is that the oxygen supply cannot last for a month. Installing oxygen regeneration devices in submarines was too costly and inefficient, and eventually it was necessary to increase the reserve of liquid oxygen tanks to replenish oxygen. However, there are pros and cons to this way, the submarine has to return to the base or find the submarine carrier to replenish oxygen tanks every once in a while.

One of Zuihou's problems is to evade the enemy's sonar detection, the traditional method is to stand still, but the experience of the Datang Navy in anti-submarine Liliang shows. Standing still is more dangerous.

The direction of guidance given by Zhang Meng is indicated. A rubber synthetic material can absorb sonar detection waves and reduce reflected energy compared to haode.

According to Zhang Meng's guidance, submarine experts began to focus on rubber materials, and asked dozens of top chemical experts to synthesize various rubber composite materials, and then carried out sonar absorption one by one, and finally found a member of the rubber composite material family, which can effectively insulate and reduce noise for the submarine by superimposing it with foam board inside and out.

With the general solution of the three key problems, the submarine experts of the Tang Army can finally complete the submarine research and development indicators given by Zhang Meng that year.

As a new generation of conventionally powered submarines developed by the Tang Empire, the Carp-class submarine came into being. And after complex sea trials, it was recognized by Zhang Meng and the navy.

The standard displacement of the Carp-class submarines increased by more than a thousand tons compared to the V-4 submarines. With a surface of 3,700 tons and an underwater capacity of 5,200 tons and a length of up to 120 meters, the increased space and tonnage are mainly allocated to 8 battery packs, 2 TRD motors and 12 oxygen and freshwater reserve tanks, which allows the submersible time to last for a month, which is self-evident in military terms.

The main engine adopts 3 TMN 6-cylinder 4-stroke diesel engines, double propulsion shafts, and a teardrop-shaped shell structure, which greatly reduces the underwater resistance, so that the external weapon system is also removed, so that the surface speed reaches 18 knots, and the underwater speed exceeds the surface speed to reach 26 knots, and the separately designed X-shaped tail rudder makes the underwater safety and maneuverability of the submarine excellent.

The armament consists of 6 533-mm torpedo tubes (6 in the bow) and 24 torpedoes, and the number of crew members has been reduced from 85 to 65 instead of increasing, reducing the logistical burden.

Of course, in the past, it was also because of the low level of knowledge among the submariners of the Tang Army, so there were many people arranged, but now after these years of training, the cultural quality of the submariners of the Tang Army has been greatly improved, and many operations do not need so many people to complete, so the personnel can be reduced accordingly.

The carp-class submarine was called a black hole by Zhang Meng because the shell of this class of submarine used a rubber sound-absorbing tile for the first time, so as to greatly absorb the detection wave energy emitted by the enemy ship, reduce the reflected energy, and make the enemy unable to hear the real position of the submarine. In line with this, the interior of the submarine is covered with a layer of foam board, especially in the engine room, which is covered in three layers, so that the sound of the engine is isolated from the outside and difficult to detect.

In this way, the noise of the carp-class submarine is very small, especially when diving, the sound of the oars is reduced to a minimum, almost the same as the noise in the ocean, in this era the sonar equipment is still very rudimentary, the enemy will not be able to detect the position of the carp-class submarine, and even know the existence of the other party.

In order to test the silence capability of the Carp-class submarines, Zhang Meng specially ordered the Admiralty to transfer more than a dozen antisubmarine destroyers equipped with the most advanced sonar detection equipment, so that the most experienced sonar crews could conduct an antisubmarine search to find the location of the Carp-class submarines.

As a result, for a whole month, more than a dozen advanced anti-submarine destroyers of the Tang Army did not find the location of the Carp-class submarines, but were successfully attacked by the other side one after another and were "sunk" one by one.

This result was shocking, Zhang Meng was very happy, the Tang Empire finally had a submarine ahead of Shijie. The Admiralty immediately approved the Jihua book for the large-scale construction of the Carp-class submarines, which was classified as S-class secret, and still claimed to be building V-4 submarines.

Zhang Meng commended the submarine designers and related experts, giving them generous bonuses and medals, and the National Academy of Sciences also recorded their collective first-class merits, rewarding them with 200 merit points each, with which they can obtain some secret resources that are not available in the outside world. (To be continued......)