If you want to talk about making cannons, then of course you have to discuss it with Lu Da. Before returning to China, Lu Da studied in Krupp, and Krupp in Germany is a world-renowned first-class gun manufacturer.
Now that Germany is at war with the Soviet Union, German tanks are constantly being replaced with new tank guns. Whether it is the 75mm tank gun on the Panther tank or the 88mm tank gun on the Tiger tank and King Tiger tank, they are all masterpieces of Krupp, so Lu Dayou has an absolute right to speak.
When Qin Baoshan said that he wanted to change the barrel of the tank gun, Lu Da immediately frowned and didn't speak there, as if he was thinking about something.
Qin Baoshan was a little embarrassed, because he knew that he had gone too far. Originally they planned to use a 20mm cannon, which is the most suitable for a light tank with a total weight of only about ten tons, but now, Qin Baoshan said that he wanted to use a 50mm tank gun. The recoil force of this kind of gun is much greater. It is not known whether the tank can bear it, and the Eighth Route Army does not have this kind of tank gun. It needs to be produced from scratch. If you want to make this kind of tank gun, it is not easy to do.
Seeing that Lu Da remained silent, Qin Baoshan continued: "If this kind of tank gun is not easy to produce, then we can also settle for the next best thing and produce a 37mm tank gun."
It is impossible for Qin Baoshan to continue to increase the caliber, he can only reduce the caliber. He is also very familiar with tank guns produced in Germany. At the very beginning, Germany used 37mm artillery. The production of this kind of gun is very large, not only used on the tank No. 3 tank, but also became an anti-tank gun for infantry. Almost every infantry company has a few of these, ready to fire at any time, if need be, without calling for reinforcements.
50 mm tank gun. The power is quite large, even at a distance of one thousand meters, it can penetrate 50 mm thick armor placed at 30 degrees. No matter how much protection is added to the little devil's Type 97 tank, the frontal armor is only 30 to 40 millimeters thick, which can be penetrated properly. Even if they hang another layer of track shoes on the front of the tank, that is to increase the thickness to 50 mm, it is still vertical thickness.
If it is a 37mm anti-tank gun, it can only guarantee a penetration depth of 40mm. Although it can also penetrate, if the little devil adds something to the front of their tank, it may not be able to penetrate it. On the battlefield, this is also very common. Even American tanks often pile some sandbags on the front to improve their protection.
When Lu Da was at Krupp, the company must have been mass-producing 37mm anti-tank guns and 50mm tank guns. So Lu Da should have some understanding of these things. Looking at Lu Da's appearance now, Qin Baoshan wondered what he was hesitating about.
Finally, Lu Da spoke, and he said to Qin Baoshan: "If we want to manufacture artillery with a larger caliber, we can do it with the current technology. But if we want to manufacture special tank guns, then Our current technology is not up to it. Not even a 37mm tank gun."
Ordinary artillery is different from tank guns, because tank guns need to have a high initial velocity when firing shells, so a lot of propellant is loaded, and the chamber pressure inside the tank gun is very high. This requires the strength of the tank gun to be large enough. Otherwise, so much propellant, once it burns, will directly smash the barrel.
At this time, a lot of advanced technology has to be adopted. Lu Da continued: "In the Krupp company, the sleeve barrel technology is used to manufacture, and the 37mm tank gun also uses this technology."
Manufacturing ordinary artillery is actually to forge a steel column, then punch a hole in the middle, expand the bore, and then pull the rifling, so it is done. But tank guns won't work. In order to achieve a sufficiently high chamber pressure, more advanced technology was used in the manufacture of tank guns.
Lu Da knew these things very well, so he introduced them.
The principle of this technology is to use the principle of thermal expansion and cold contraction from two casings inside and outside. First, after the outer barrel is heated, it expands. After expanding to a certain extent, the barrel prepared for the interior can be inserted into it. After plugging, let the outer barrel cool down quickly, so that the inner barrel is tightly wrapped. In this way, the degree of bore pressure resistance can be increased.
This technique is very simple to say. But in practice, it will be quite complicated. Especially it needs to be very precise. During the heating process, the outer barrel needs to constantly measure the size it expands to. Then, under the appropriate size, plug the inner barrel into it. Based on the current production capacity of the Eighth Route Army, it is estimated that?? Certain degree of difficulty.
Lu Da also learned real skills in Krupp, and he knows all these technologies clearly. So now that Qin Baoshan made this request, he felt that it was difficult to do it in terms of craftsmanship.
In order to allow the barrel to withstand sufficient chamber pressure, the designers also came up with clever tricks. For example, at the very beginning and when it was the highest, the British liked to wrap steel wires around the gun barrel. They tightly wound the square-section steel wire around the gun barrel, and resisted the firing stress of the gun barrel through the tension of the steel wire to enhance performance. Later, many naval guns were used.
As for the current Krupp method, it was not invented by them. The British used this barrel tightening process on their Armstrong guns. The outer tube was first heated and then put on the inner tube. After the outer tube cooled, it shrank, and the inner and outer tubes were tightly fitted together. If two do not work, there may be a third outside.
Hearing what Lu Da said, Qin Baoshan understood a little. Isn't this the same as the production process of the old sleeve? In order to avoid the inner gun barrel from blowing up, another gun barrel is wrapped outside. This kind of technology is not very advanced anymore, he thought about it, and said to Lu Da: "I have a new method here, I wonder if we can try it."
Hearing what Qin Baoshan said, Lu Da opened his eyes wide. He knew that Qin Baoshan was a very capable person. He will always come up with various solutions to problems. Now that Qin Baoshan proposes to manufacture large-caliber tank guns, he must have his own ideas. Lu Da said to Qin Baoshan: "What can you do? Tell me quickly." (Remember this site's website: www.hlnovel.com