Hearing that Zhao Yan was going to test shoot the strange bed crossbow in front of him, Shen Kuo, who was eager to see the effect, immediately spoke: "Okay, I'll go and call the people outside and try the power of this bed crossbow!" ”

The bed crossbow of the Song Dynasty is very powerful, generally the small single-bow bed crossbow also needs five to seven people to operate, the largest eight-cow crossbow needs hundreds of people to operate together, the reason why so many people are needed is because the greater the power of the bed crossbow, the more people are needed to pull the crossbow arm apart, in addition to special aiming and shooting personnel, now there are only Zhao Yan and the four of them in the backyard, but it is an old man and two weak scholars, as for Zhao Yan, he is a teenager, and he can't open the bed crossbow at all, so Shen Kuo will say to call people.

"No need, I can pull it away by myself!" Zhao Yan stopped Shen Kuo with a smile.

"This ...... How is this possible? Shen Kuo said with a shocked face again when he heard this, he had already tried the strength of the crossbow arm just now, that kind of strength was definitely not worse than a real bed crossbow, and it would take at least five strong men to pull it apart, and Zhao Yan didn't look like that kind of person with natural divine power. As for Su Shi, he directly thought that Zhao Yan was telling a joke, and the one that a person could pull away was not a crossbow, but a bow.

But then Zhao Yan really walked to the side of the bed crossbow, and then pulled out a few ropes from the winch at the back end, and the sharp-eyed Shen Kuo saw that these ropes were combined by several pulleys, which made him stunned, and vaguely seemed to understand something.

I saw Zhao Yan hang a special iron bracket on the rope at the very front, with jagged hooks on both sides of the bracket, and then put the bracket on the arrow slot. At this time, Shen Kuo appeared, and there were also jagged iron plates on both sides of the arrow groove, which could be bitten with the sawtooth on both sides of the machine bracket. Seeing this, Shen Kuo immediately understood, these two biting sawtooth can make the bed crossbow not have to be opened in one go, and it can also adjust the opening force of the crossbow arm and adjust the size of the range, although this design is simple, but it can allow soldiers to save body when operating the bed crossbow, which is definitely a great Ming.

In addition, Shen Kuo also realized that the crossbow machine on this bed crossbow had been removed. Zhao Yan directly buckled the bowstring on top of the iron bracket. After making these preparations, Zhao Yan immediately turned the winch to tighten the rope, and then saw that the pulleys were also pulled up by the rope, and Zhao Yan turned the winch. The crossbow arms on both sides, which seemed to be very heavy, made a "squeak" sound. Then it was slowly pulled away.

"Haha~. I see, these few pulleys without a fixed pulley can allow a person to wield several times the power, so the king of the county can easily pull this bed crossbow apart! At this time, Shen Kuo suddenly laughed. The history of the appearance of pulleys is very early, China has been used in the Han Dynasty, and there are also discussions on pulleys in the Mojing, but they are very general and do not count jù to explain, which is also in line with the relatively vague scientific concepts of the ancient Chinese.

Seeing Shen Kuo's happy appearance, Su Shi was still confused, and then Zhao Yan said with a smile: "Judge Shen is really knowledgeable, these unfixed pulleys are called movable pulleys, a movable pulley can make people wield twice the usual power, and now I combine the three movable pulleys to make a person wield eight times the strength, so don't look at my strength is not great, but I can still pull the crossbow arm apart very easily!" ”

Just when Zhao Yan was speaking, the old carpenter Zhu Hong brought a crossbow arrow and put it in the arrow trough, Shen Kuo immediately stepped forward to aim, there was a huge grass target at the other end of the yard, and after Shen Kuo adjusted the angle of the bed crossbow, Zhao Yan held a wooden hammer and smashed it heavily on the iron machine, and the bowstring was immediately released, driven by the huge force, the crossbow arrows in the arrow slot shot out like lightning, and then with a loud "bang", it shot heavily on the wall one foot away from the grass target.

"This ...... The accuracy of this crossbow is too bad, isn't it? Shen Kuo said again dumbfounded.

Originally, Shen Kuo saw that there were so many exquisite structures on this bed crossbow designed by Zhao Yan, and he was full of confidence in this kind of bed crossbow, but the effect of the shooting made him a little disappointed, the strength was there, but the accuracy was too far behind, you must know that the target was only twenty steps away, but it was more than a foot away from the target, and the maximum range of the bed crossbow could even reach three hundred steps, according to this range, this kind of bed crossbow was no longer a deviation, but there was no direction at all, although the accuracy of the bed crossbow itself was not very high, but at least the general direction is still no problem.

In contrast, Su Shi was even more shocked, he didn't expect that this bed crossbow with two hardwood instead of crossbow arms could really shoot crossbow arrows, although the accuracy was poor, but the strength was definitely not worse than the real bed crossbow, the spear-like crossbow arrow was now trembling on the wall made of blue bricks, which made him unable to understand the truth anyway.

Seeing the shocked expressions of Shen Kuo and the others, Zhao Yan spread his hands and said: "The two of you see the shortcomings of this new weapon, this thing is not worse than the bed crossbow, but it has a huge flaw in terms of accuracy, and now I don't have a craftsman in this area, so I can only study it to this point, and the rest depends on whether you can find a special craftsman to continue researching." ”

"King Jun, what is in the wooden box at the root of the two hardwoods, the elasticity of the crossbow arm of this new bed crossbow should come from inside, but I don't understand, what is it that can provide such a large elasticity?" Shen Kuo asked very eagerly, although he was a little disappointed by the accuracy of this weapon, he was still interested in the contents of the box.

Hearing Shen Kuo's words, Su Shi came to his senses, and immediately came to the crossbow arm to study the two wooden boxes, but unfortunately he is really not very good at this kind of clever thing, Shen Kuo can't figure things out, and he doesn't want to figure it out, in fact, in Zhao Yan's opinion, Su Shi is a liberal arts student, while Shen Kuo is a science student, and the thinking and talents of the two are completely different.

There is nothing special about the two wooden boxes, the things inside are the key to this bed crossbow, so Zhao Yan asked Zhu Hong to remove the two boxes, but at this time Shen Kuo and Su Shi saw that the inside of the box was an iron casting part, and the two bundles of very thick leather and cow tendon-like things were tightly fixed, and the hardwood that served as the crossbow arm was inserted in these two bundles of leather and cow tendon, this thing was actually a torsion spring, although it looked simple, but it could provide strong power.

"I see, I understand, I didn't expect that two inconspicuous bundles of leather and beef tendon could wield such great power!" Shen Kuo is worthy of being one of the greatest physicists in ancient China, and he can see the principle of this torsion spring at a glance, in fact, it is not surprising that some ancient agricultural tools will also use this torsion principle to fasten, but no one has ever thought of applying this principle to weapons.

Although Su Shi is not as professional as Shen Kuo, he is not a stupid person, and when he saw the torsion spring, he quickly understood its principle, and he also felt incredible, he never dreamed that Zhao Yan could provide so much power with such a simple thing, which was not inferior to a real bed crossbow.

"Two, I call this thing a torsion spring, as long as it is applied properly, it can provide power that is no worse than a real crossbow arm, but Zhu Hong They are carpenters, and they don't know much about things like leather and cow tendons, and the torsion springs made look fine, but it is difficult to find two springs with similar elastic force, which also makes the strength of the two crossbow arms uneven, so that the crossbow arrows shot will naturally have no accuracy." Zhao Yan opened his mouth again at this time.

When he saw this bed crossbow without a crossbow arm from Cao Lu, he thought of using a torsion spring instead of a crossbow arm, which also appeared in Western history, that is, the ballista that had been equipped by the Greeks on a large scale, but Zhao Yan's bed crossbow did not completely copy the ballista, but only turned the expensive crossbow arm of the bed crossbow into a torsion spring, and then added some excellent designs on the ballista, and made some improvements by himself, and finally became a combined weapon of the bed crossbow and the ballista in front of him.

"Torque springs, this name is good, there are special leather craftsmen, tendon craftsmen in the ordnance prison, and there are also silk hammering craftsmen who make bowstrings, these people are very familiar with leather, animal tendons and tough silk threads, I believe that as long as they are given a period of time, they can make torsion springs with average strength!" Shen Kuo was also very excited when he heard this.

"The cost of the crossbow arm is expensive, and it takes a long time, so it limits the output of bed crossbows, but if you use this kind of torsion spring, you only need some leather, animal tendons and silk threads, these things are not very expensive, so that the original expensive bed crossbows will be slowly eliminated, and at the same time, more bed crossbows can be produced to equip the army, greatly improving the combat power of our Great Song army!" Su Shi also muttered to himself at this time, and when he said the end, his face also showed a little excitement, as a patriotic Song man, he was always sad about the weakness of the army's force, although the appearance of a weapon could not completely reverse the status quo, but it was better than before.

"King Jun, please allow the lower official to send this bed crossbow to the ordnance superintendent, and then organize craftsmen to study overnight, and the problem of uneven torque will definitely be solved in the shortest possible time!" At this time, Shen Kuo solemnly saluted Zhao Yan and said, he has now thrown himself to Zhao Yan, the king of the county, and he has benefited a lot just from the new bed crossbow in front of him.

Seeing Shen Kuo's excited appearance, Zhao Yan hesitated for a moment and finally spoke: "Judge Shen, there is naturally no problem for you to take this bed crossbow away, but when I designed this bed crossbow, there is another function, which needs to be explained to you in advance, so as to facilitate your next research and manufacturing." (To be continued!)

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