Although Li Rujuan bought a batch of 105mm and 150mm high-strength seamless alloy steel pipes from Europe this time, the quantity was not large, only enough to make dozens of artillery pieces.

Because this alloy steel is so expensive, it is unrealistic to buy barrel steel alone to manufacture artillery on a large scale. A small amount of trial manufacturing, the accumulation of experience is OK.

However, although large-caliber artillery is subject to alloy steel, the steel required for artillery below 75mm can still be manufactured by the Northern Iron and Steel Company, and the 75mm mountain cannon is now in mass production, but the output is not large.

Song Zhewu was very busy, and Zhou Liqun knew that Song Zhewu could come to the Weapons Research Institute to guide the work opportunity, so naturally he couldn't let him slip away easily.

Zhou Liqun seized the opportunity and showed Song Zhewu a self-made 55mm combat defense gun.

This was developed by him according to Song Zhewu's request and with reference to the 37-mm anti-aircraft gun of the German company Rheinmetall. In fact, this type of anti-aircraft gun is basically an enlarged version of the Krupp 37-mm anti-aircraft gun.

The reason why Song Zhewu gave up the production of technically mature 37-mm anti-aircraft guns and switched to larger calibers was because now, and even in the foreseeable future, the armor thickness of tanks is much thicker than in World War I, and 37-mm anti-aircraft guns are no longer of much use. It is okay to deal with the thinly armored bean tanks of the Japanese army, but it is absolutely not good to deal with the Soviet tanks.

At the beginning of World War II, the Germans used 37mm anti-aircraft guns to beat the 14 guns of the British Matilda 1 light infantry tank, but only broke a little armor.

Of course, this tank designed and produced by the British in the mid-30s was a bit perverted compared to the tanks of the same era, and its front armor thickness reached a rare 60mm at that time.

Therefore, the production of larger-caliber anti-aircraft guns has become a necessity, and this is also to lay the foundation for their own development of tank guns.

It's just that the 75mm caliber anti-aircraft gun that Song Zhewu needs has not yet been successfully trial-produced, and the main reason for this is steel.

The anti-aircraft gun requires a high initial velocity of the projectile, so the chamber pressure must be higher, and the requirements for the quality of the steel are also high.

Of course, Song Zhewu will not forget to produce anti-aircraft weapons, anti-aircraft machine guns are a must, anti-aircraft guns will not be forgotten either, before he did not have a powerful air force, special anti-aircraft weapons with fierce firepower were necessary.

It's just that what he wants most is the 88-mm large-caliber anti-aircraft gun that Krupp is secretly developing.

The 88 gun can be said to be the most successful artillery in the world in World War II. Best of all, although it was designed as an anti-aircraft gun, it was the use of anti-tank guns that made it famous all over the world.

It is said that during the entire World War II, no tank in the world could withstand its thunderous blow, and a 22-pound armor-piercing projectile could knock a large hole in the frontal armor of a heavy tank with a diameter of four inches at a distance of nearly two kilometers.

Whether it is the Soviet army's KV-1, KV-2 and T-34 and other heavy tanks, or the British Martils II with an armor thickness of nearly 80 mm, or the US army's M4 Sherman, in front of it, they are all paper tigers.

It's just that this type of big killer, because of technical reasons, at least Song Zhewu still doesn't dare to hope for it now. If you want to get close to others and engage in any joint development, Song Zhewu didn't dare to think about it.

In terms of artillery design, compared with the designers of Krupp and Rheinmetall, it is no exaggeration to say that it is like a gap between a schoolboy and a university graduate. No one is going to work with someone who won't get any helpful advice on their own, at least when the other person doesn't see the benefits enough to appeal to them.

However, Song Zhewu was not discouraged, he could first develop small-caliber anti-aircraft weapons, and after accumulating experience, perhaps he would also have his own 88 gun.

Moreover, he is not without strengths now, at least he now has an advantage that others do not have, and it is also unattainable, that is, he can easily develop the propellants and explosives of the most advanced weapons today, and it is by no means one, he can easily come up with a list of high-explosive charges.

In terms of advanced explosives and propellants, Song Zhewu is definitely ahead of the world for decades. It's just that he doesn't dare to take out a lot of advanced explosives technology now, he needs to come little by little, as long as the propellant and explosives used in his weapons can always be a little ahead of the world.

Song Zhewu also has a weapon that is very suitable for him as a poor man to be developed by Zhou Liqun, that is, the famous bazooka.

The bazooka is definitely the most cost-effective weapon, not only now, but even 80 years later.

It can hit not only tanks, but also pillboxes, fortifications and other firing points, and even attack low-altitude and low-speed aircraft.

Song Zhewu's memory of his previous life is very clear, and the Afghan guerrillas used it to fight the Soviet army's helicopters.

The bazooka drawings that Song Zhewu handed over to Zhou Liqun were drawn based on his memory. However, because the principle of the bazooka is too simple, Song Zhewu still drew the schematic diagram meticulously. The follow-up development and production drawings are not up to him, the commander, but to Zhou Liqun and others.

On Song Zhewu's schematic diagram, the main body of this bazooka is a seamless steel tube about 1m5 long, with a diameter of 60mm, a simple mechanical sight welded on the left side, two grips with wooden guards and a large wooden shoulder rest below, there is a small square flame shield at the mouth of the barrel, and there is a trumpet-shaped bracket welded by steel wire at the tail of the barrel.

A metal reinforcing ring is provided in the middle and rear of the barrel body to reduce the possible deformation of the barrel body. Above the tail of the barrel is a junction box from which two wires are drawn, one connected to the battery in the shoulder rest and the other to the trigger, which is used to control the closing of the wire.

The transmitting mechanism is composed of the transmitter body, the trigger, the trigger spring, the circuit contact ring, the dry cell battery pack and wire, and the test lamp. The middle of the barrel is covered with a leather heat-resistant sheath, and there is also a convenient carrying strap that attaches one end to the bottom of the grip and the other end is tethered directly to the back of the barrel.

The equal-caliber rocket designed by Song Zhewu has a steel conical hood at the front end and a steel conical medicine cover at the rear, with a total length of 600mm and a mass of 1.65kg, and is composed of four parts: a warhead, a fuse, an engine and a stabilization section.

Among them, the rocket engine body is a section of seamless steel pipe, the front part is riveted and welded with a fuze chamber, the middle hole is equipped with a firing pin body and an isolation spring, the upper part is screwed with a detonating body, and the front end of the latter extends into the bottom of the main charge.

The principle of the fuse is extremely simple, the firing pin body is usually separated from the detonator by the isolation spring, and is fixed by a steel wire safety pin, the safety pin is withdrawn before launching, when the rocket hits the target, the projectile body slows down, and the firing pin body compresses the isolation spring due to the habitual effect, and the detonator is fired and the main charge is detonated.

The tail of the engine is screwed with Laval nozzle, the inside is pressed with a medicine baffle plate, the nozzle mouth has a sealing gasket, and the engine is equipped with 8 single-hole double-base propellant columns, which are fixed in the front of the engine with a solid medicine column.

The most critical thing about the rocket is the hollow charge technology of the rocket and the armor-piercing warhead.

In Song Zhewu's memory, the hollow charge technology was invented by the Swedes about 40 years ago. Without the use of hollow charge technology, the armor-piercing ability of the bazooka will be greatly reduced.

According to Song Zhewu, the range of this rocket is about 200 meters, and the thickness of armor piercing should be about 40mm.

Originally, Song Zhewu could now develop rockets with an armor-piercing thickness greater than 300mm by improving the propellant, but now it is completely unnecessary to do so.

Because, at this time, the front armor of the T-18 tank in service in the Soviet Army was only 16mm, the British Vickers 6-ton tank, as well as the Vickers E type, and the American Christie wheeled dual-purpose tank The armor did not exceed 20mm.

Throughout the thirties, there were very few tanks with armor exceeding 40mm. In other words, Song Zhewu believes that his current rocket's 40mm thick armor-piercing ability will be enough in ten years.

Of course, the principle and technique of his bazooka are to be kept absolutely secret, but he still has to take precautions, and he does not dare to guarantee that he will not be captured by the enemy in battle.

The technology of the rocket launcher is very simple and easy to imitate, but the armor-piercing ability of the rocket is not something that can be easily done casually. Song Zhewu wanted to delay the enemy's mastery of the Great Armor-Piercing Rockets as much as possible, at least for a while behind the ones used by his Fourth Route Army.

The schematic diagram of the bazooka was handed over to Zhou Liqun alone, and only Xiao Guodong was present.

Regarding the power of the bazooka mentioned by Song Zhewu, not only General Xiao Guodong was suspicious, but even Zhou Liqun was a little unimpressed at the beginning.

It's no wonder that the rudimentary structure of the bazooka is not even as complex as an ordinary rifle, and it can be so powerful? It's hard to believe.

However, when Song Zhewu explained the principle of hollow charge and shaped energy jet, although Xiao Guodong still didn't understand it, Zhou Liqun already understood.

Zhou Liqun said excitedly: "Commander, after we have such a weapon, doesn't it mean that we are no longer afraid of tanks, and all tanks are vulnerable in front of us." ”

Song Zhewu looked at Zhou Liqun and shook his head and said: "I can't say that, the technology of the tank must also continue to develop, at least in terms of armor thickness and armor steel, all countries will continue to improve." If we don't improve the power of our rockets, we may not be a threat to tanks in a few years. Moreover, I still think that the best way to deal with tanks is to use tanks with higher surnames, and bazookas can only be used as a means of our anti-tank, not the only one. ”

Song Zhewu said solemnly: "The bazooka should be kept strictly secret, especially the technical principle of the hollow charge of the rocket. Study the design of the study, as well as every part of the process, and contact not only with as few people as possible, but also as few people as possible. ”

Song Zhewu said to Xiao Guodong again: "Tell Fang Zhen that the secret specifications of the bazooka should be the same as that of our planes and tanks, and they should be listed as the highest. ”

(To be continued)