The Jiannan army was indeed cutting down trees on a large scale, Liu Dehai led 5,000 soldiers to put down the tall and stout trees on the slopes on both sides, and Liu Jun led the cavalry to pull these trees back to the barracks with horses. In half a day, the open space at the front of the camp was filled with logs.

These logs were used to build fences for the barracks, as well as shelters and turrets, but they were not the main purpose, and the trees were cut down for large-scale construction of stone throwers to siege the city. The road was rugged, and heavy machinery such as a stone thrower could never be accompanied, so from the very beginning, Wang Yuan gave up this kind of equipment necessary for attacking the city and chose to build this thing at the scene of the need.

Entering the Nanzhao Kingdom to fight in the middle of the country actually provided the convenience of manufacturing, because the most important thing here is the log material. This is also the reason why in the city of Langdong, when Li Mi brought hundreds of craftsmen to Wang Yuan, these craftsmen were asked by Wang Yuan to be recruited by Li Mi in order to build trebuchets at the siege site. At present, the city of Yangba and the subsequent Longshou Guan Taihe City are the fortified cities of Nanzhao, and the stone throwing machine should also come in handy at this time.

The stone thrower is a commonly used heavy equipment, which is called a stone cannon truck or a flying stone car. **The commonly used standard trebuchet is still a little smaller in Wang Yuan's opinion, although it can throw a boulder of thirty or forty catties up to a distance of three hundred and fifty steps, but it is too condensed in terms of size and range. Wang Yuan understands that this is for the convenience of carrying. The 17-foot-tall stone thrower, equipped with a solid wood wheel on the site, can be pulled by a horse to move with the army, and the mobility is also very good.

However, at this time, what Wang Yuan needed to make was a giant trebuchet that was at least twice as large as the standard stone throwing cart and had a projectile distance of at least 100 steps. On the same day, when the Tubo army was defeated outside the city of Wangzhou, many 'throwing buildings' made by the Tubo army were captured. The throwing building is actually the Tibetan version of the trebuchet, although rough, but it looks much more powerful than the Chinese standard stone thrower.

During his stay in Wangzhou for half a month, Wang Yuan carefully studied the abandoned buildings and found that the throwing buildings in Tubo and the trebuchets in the Tang Dynasty had their own advantages and disadvantages. The Datang standard trebuchet is relatively strong, and the accuracy of the projection is also better, while the throwing floor in Tubo is rougher, but the weight of the projection is large and the distance is also far. Slightly different in terms of structure.

Wang Yuan spent a lot of energy to draw some drawings, hoping to absorb the advantages of the two and create a new generation of stone throwing machine with high precision, long projection distance and large projection weight. So when the army was cutting wood on a large scale, Wang Yuan gathered nearly 900 craftsmen in the army, selected 100 of them who were good at making ordnance, and discussed with more than 100 craftsmen how to make a satisfactory trebuchet according to the requirements.

Wang Yuan studied with the craftsmen for an afternoon and a whole night, and the next morning, the craftsmen began to try to make a new stone thrower. More than 100 people worked together, the speed of manufacturing was amazing, and the production began in the morning, and at noon, a giant stone throwing machine with a height of two zhang and a throwing arm of five zhang stood in the camp.

On the base made of log arrangement, four thick logs two feet high are erected side by side on both sides, and the middle is connected by thick logs to form a frame. At the top of the frame is a sturdy shaft made of sandalwood, which is held firmly by diagonal braces on each side of the frame with four logs at different heights. The five-zhang long throwing arm is installed on the rotating shaft, and the shorter end is tied with a thick rope to a huge bluestone weighing 1,000 catties as a counterweight, and the other end is a long arm with a huge throwing basket.

Two thick ropes attached to the top of the long arm, one attached to a twisted shaft at the base, and the other short, thick, with a thick iron hook at the front. Dozens of soldiers worked together to winch the winch to pull down the long arm at one end of the basket to load the stones, and hooked the wooden shaft with the iron hook of a short rope. When firing, the wooden shaft was knocked away with a sledgehammer, and after the iron hook was loosened, the thousand pounds of bluestone fell suddenly, driving the long arm to rise suddenly, and the stones in the throwing basket were thrown far away by inertia.

This behemoth caused everyone to marvel, and many people saw such a huge behemoth for the first time. After lunch, the first test firing of the giant stone throwing machine took place in front of the battalion. Wang Yuan led everyone to watch, only to see an old craftsman commanding thirty soldiers to shake the shaft of the motive, and in the squeaking and squeaking sound, one end of the high throwing arm was pulled off the ground, and the other end of the thousand pounds of boulder was slowly hung into the air. The entire throwing arm immediately becomes an arc. After loading a hundred-pound stone in the throwing basket, the iron hook was buckled, and a bamboo whistle sounded, and the audience was silent. Rolling up his sleeves, revealing the pimples and black muscles on his arms, Wang Dahei came on the field with a hammer, spit twice in the palm of his hand, rubbed it, and slammed it down with a loud sound of holding the big iron vertebrae high against the wooden shaft that hooked the iron hook.

The wooden shaft flew out, the iron hook was loosened, and the boulder quickly fell and smashed heavily on the ground, splashing up dust. The long arm at one end of the basket was quickly cocked, and the whole trebuchet made a loud clicking sound, and with a whoop, the hundred-pound boulder in the basket flew high into the air, quickly becoming a small black dot. Soon after, it fell on the ground in the distance with a thud, and a puff of yellow smoke rose from it.

"It worked!" Everyone smiled and high-fived.

A big stone in Wang Yuan's heart also fell to the ground, and he was originally worried that this blind expansion of the trebuchet would not succeed, because a good machine must have accumulated many times of experience to achieve a perfect balance. Every change could render the stone thrower unusable or even injure itself. Fortunately, after careful measurement, the size of the original trebuchet was enlarged according to a certain proportion, and it seems that the balance of the mechanical structure was not destroyed.

And what Wang Yuan is most worried about is whether the five-zhang long throwing arm can withstand such a violent impact and inertia, which is the most critical place. After combining the opinions of the old craftsmen, the throwing arm made of a whole hard and elastic pear wood was tied and reinforced with extremely elastic ash wood, and it withstood the tremendous impact and inertia.

"Report to the lieutenant marshal, the throw distance is four hundred and twenty paces. smashed a big pit half a foot deep, so powerful. The soldier who measured the distance rushed to report.

Wang Yuan smiled and nodded, although it was not as far as he imagined, but four hundred and twenty steps had already exceeded the range of five hundred meters according to the distance standard of later generations, and Wang Yuan was still very satisfied with this. The fly in the ointment is that the distance of the launch deviation is relatively large, because the whole structure is not symmetrical, and the thrown boulder does not fly in a straight direction. Moreover, after the launch, the entire trebuchet bounced off the ground and almost overturned. This is the reason why the chassis is not heavy enough. It seems that when launching, it needs to be fixed on the chassis with a hook pile and firmly nailed to the ground.

Next, in order to test the life of the trebuchet, another non-stop firing was carried out, and minor adjustments were constantly made. After firing more than 50 times, the throwing arm was finally overwhelmed and broke into two with a 'click'. But Wang Yuan was already very satisfied, and he knew that it was absolutely impossible to expect this kind of thing to be used for a long time. Without metal elements, a structure that is completely connected by wooden mortise and tenon ropes cannot be sustained. Unless all of them can be replaced with metal components, they can be used as combat equipment for long-term use.

Wang Yuan immediately ordered this giant trebuchet to be used as a template, and thousands of soldiers and horses were dispatched to make this thing in large quantities immediately under the guidance of craftsmen. A vigorous campaign to make Shenwei cannons was launched under the city of Sheep and Baa.

Over the next two days, trebuchets began to take shape and stood tall in the open space outside the barracks. The more continuous the production of this object, the more experienced it became, and the site of the Shenwei Cannon was also equipped with eight wooden wheels that could be pushed or pulled away, making it easy to adjust the travel distance. The wooden wheels are fixed when firing, and the wooden stakes are fixed along the surrounding chassis without rolling over. What's more, because the installation of the wooden wheel raised the chassis by half a foot, which is equivalent to the entire Shenwei cannon being raised by half a foot, the distance of the projectile was twenty steps more, which was an unexpected surprise.

The amount of work is huge, from the hillside to cut down the wood, but also to dig out hundreds of square pieces of heavy boulders, more than five giant trees to be cut big eyes to make mortise and tenon casting, and fixed testing. Nearly 10,000 soldiers and horses threw themselves into this large-scale catapult movement, and they were busy one by one.

On the first day, thirty Shenwei guns were put into production, on the second day, ninety were formed, and on the third day, one hundred and sixty. The more skilled you are, the faster you will progress. After three days, a series of towering Shenwei cannons were sent out in front of the ** barracks, like monsters facing the direction of the sheep and Baa City, waiting for the moment of great might.