Chapter 198 AIP

Although we can't count on nuclear submarines in the short term, Yannick was not disappointed.

After all, in the 21st century, decades later, not every country will be able to use nuclear submarines. For many countries, there are insurmountable technical and financial difficulties in manufacturing nuclear-powered submarines. Therefore, while nuclear-powered submarines are vigorously developed, conventional-powered submarines have not withdrawn from the stage of history. Moreover, conventional-powered submarines are more suitable for offshore and shallow sea operations than nuclear submarines.

However, conventional-powered submarines have a big flaw, which is that they cannot sail underwater for a long time, because the capacity of the batteries installed on the boat is limited, and they must often float to the surface of the sea to "breathe", that is, use diesel engines to charge batteries in the snorkel state, which is easy to be discovered by the enemy, and the noise when the diesel engine charges the battery is also easily detected by sonar and other hydroacoustic equipment. In this way, the exposure rate of submarines is greatly increased, and both the concealment of the attack and its own survivability are greatly affected.

In order to solve this problem, all countries have made long-term explorations and efforts, and the development of various AIP power devices has been successful and has begun to enter the practical stage.

The so-called AIP is the abbreviation of "Air Independent Propulsion".

Since the AIP power unit does not require oxygen to operate normally, it can significantly improve the submarine's underwater endurance after being installed on the submarine, increasing its underwater lurking time to 2-3 weeks, greatly reducing the submarine's exposure rate during cruising. In this way, the bottleneck that has always affected the combat effectiveness of conventional power submarines has finally been solved. Some people figuratively compare conventional submarines equipped with AIP systems to "green nuclear submarines", meaning that they have both large cruising power comparable to nuclear submarines, but without the potential dangers and high costs of nuclear submarines.

As early as the late period before and after World War II, the Soviet Union, Germany and other countries had already been involved in the research of AIP power units.

In 1935, the 18th Central Design Bureau of the Soviet Union proposed to use the AIP system on submarines and tested it on the M-92 submarine, obtaining a large amount of test data. However, the technology was not yet mature at that time, and the designer proposed the air-independent technology only as an experimental topic.

During World War II, the German Walter Company tried to use compressed hydrogen peroxide in submarines as an underwater oxygen source for diesel engines. People who have studied chemistry know that hydrogen peroxide can be decomposed into oxygen and water. When the submarine is running underwater, the heat energy of the diesel engine heats hydrogen peroxide, and then produces oxygen for the diesel engine. Later, Germany built a few such AIP submarines.

But Yannik doesn't like hydrogen peroxide because it is extremely unstable when converted into oxygen! In 2000, the Russian "Kursk" nuclear submarine was due to the leakage of hydrogen peroxide inside the training torpedo, which instantly exploded and caused a fire. The high temperature caused seven torpedoes equipped with real warheads to explode, resulting in the largest nuclear submarine sinking disaster in history. All 118 officers and soldiers on the boat died.

In later generations, there are three practical AIP schemes: closed-cycle diesel engines, Stirling engines, and fuel cells.

The fuel cell technology is impossible to achieve in this era; using liquid oxygen or hydrogen peroxide is too dangerous. And it was not until 1993 that Germany successfully tested a 250-kilowatt closed-cycle diesel engine system on the retired 205-class submarine U-1. Yannick didn't think he could make German technology leap half a century in one go; therefore, the safest way to use current technology was to use the Stirling engine.

"General Dönitz, have you heard of the Stirling engine?" Yannick asked.

Dönitz nodded. "Are you talking about the Stirling engine invented by the British Robert Stirling?"

"Yes."

The 17th and 18th centuries were an era of genius. There is a joke that in Paris, one copper coin can buy three geniuses.

Watt added a governor to the steam engine, and mankind entered the steam age, and then there were trains and ships. However, this steam engine consumed too much coal. At that time, some people believed that if hot gas was used instead of steam, the heat loss caused by condensation of steam could be avoided.

Based on this idea, British scientist Robert Stirling invented the closed-cycle hot air engine with external combustion, the "Stirling Engine" in 1816. The Stirling engine outputs power through the working medium (hydrogen or helium) in the cylinder, through a cycle of cooling, compression, heat absorption, and expansion, so it is also called a hot air engine.

However, there was a lack of good heat-resistant materials at that time, and the French engineer Nicolas Leonardo Sadi Carnot had not yet proposed the Carnot cycle. People had limited understanding of the performance of hot air engines, and the efficiency and power of known machines were very low. After the mid-19th century, with the invention of high-efficiency internal combustion engines and the large-scale exploitation of oil, the development of Stirling engines stopped.

This Stirling cycle hot air engine does not emit exhaust gas, and does not require other air except the original air in the combustion chamber. Therefore, it is also suitable for urban environments and outer space. It is an ideal solution to ensure that conventional-powered submarines can sail underwater for a long time without surfacing.

Dönitz was a little embarrassed. "But your highness, we don't have technical reserves in this area. If we want to use this technology on submarines, we have to start from scratch. It may take several years."

"It won't take a few years, General Dönitz." A proud smile appeared on Yannick's face. "Soon we will have ready-made research results."

Dönitz couldn't help but be stunned. "Ready-made? Where is it?" I thought it was researched by His Highness's secret scientific research department, but unexpectedly His Highness mentioned another country.

"The Netherlands. Their Philips company has been developing the Stirling engine a few years ago. I heard that it was finally successfully developed not long ago." A company that makes light bulbs develops engines? I don't know what they were thinking, but this was an advantage for him.

Of course, this Stirling engine can only be regarded as a prototype, and Yannick is not prepared to become fat in one bite. He does not expect the current Stirling engine to provide hundreds of kilowatts of power like later generations. It only needs to provide a few Ten kilowatts of power is enough. In addition to supplying normal lighting, electronic equipment and living facilities on the boat, the remaining energy can be used to propel the submarine. It is enough for the submarine to maintain continuous navigation for half a month at an underwater speed of a few knots.

Dönitz said excitedly. "That's great. The next batch of 'Tiger Sharks' should be able to use this engine." After all, the most important thing is to allow the submarine to have the ability to sail underwater for a long time. Reducing the snorkel status is the most important thing. Can avoid danger more effectively.

Then the two talked about wolf pack tactics. "General Dönitz, what do you think are the shortcomings of the 'Wolf Pack Tactics'? Don't have any worries, just say it."

Dönitz hesitated for a moment and then spoke carefully. "Your Highness, there are some problems. The biggest problem is the ownership of command authority. Should the submarine commander at sea or the command on the shore give unified orders for operations? If the command on the shore gives unified orders for operations, it will be difficult to do so. If we adapt to the situation, we may deploy fighters; but if we leave full power to the submarine commander at sea, once the enemy masters the method of locating based on radio transmission signals, our submarine's location will be easily exposed. "

Yannick knew that Dönitz's worries were not groundless. British experts from the original time and space carefully studied the "wolf pack" tactics of German submarines and believed that if they could capture the signal sent by the tracking submarine and then use the signal to determine the submarine's position, The aircraft can carry out a quick and effective attack, making it impossible for the "wolf pack" to attack. British scientists have developed a small high-frequency directional detector that can accurately measure the position of a tracking submarine using the azimuth data measured by several instruments.

Coupled with the fact that Britain and the United States sent a large number of destroyers and aircraft for escort, the "wolf pack" that was extremely arrogant at the beginning turned into a "sheep pack" that was unable to fight back.