I saw that in the backyard, after three days of sleepless sewing, the hundred cowhides were finally successfully sewn into five huge cowhide balloons, and the group of bamboo craftsmen also made baskets for him, and he was also very happy.

Although every embroiderer sister has dark circles under her eyes, her hands are even more scarred.

After all, this sewn cowhide is not easy to do, although it is a good material for making hot air balloons, but it is not a good material for sewing, it is very tough, and ordinary needles and threads cannot be sewn at all.

It is necessary to use a large needle and thread, and it takes a lot of strength to penetrate these tough cowhides, which is relatively simple and not difficult for a martial artist like them.

But they are all a group of women, and their strength is not outstanding, so when sewing these cowhide balloons, they really worked hard and gritted their teeth, resulting in a lot of scars on everyone's hands.

Even the little girl Su Xue is no exception, the originally snow-white and slender ten fingers are a lot rougher at the moment, and they are also red, so that fortunately she is also a little distressed, and she took good care of it in her arms, and then she reluctantly let go.

Although there are many people in that group of bamboo craftsmen who were injured because of basket weaving, and their hands were scratched by bamboo strips, but fortunately they didn't care too much, after all, they were a group of big men, and it was nothing to get a little injury on their hands, so they should be trained to do so, I believe that after this battle, their basket weaving skills must have risen greatly, haha.

But although they thought about it like this, they were still very grateful, so they directly asked Liu Quan, the housekeeper of Xingwangfu, to give them double the remuneration and then politely sent them back.

At this point, I was completely relieved, and the breath hanging in my heart finally relaxed a little, and I felt that everything was really ready and only the east wind was owed.

Thinking about it, he didn't delay, because at this time all the preparations including the utensils were ready, and he assembled them directly by hand, and assembled them into real hot air balloons according to the method in his mind, such as the sewn cowhide balloons and bamboo baskets, plus the oil canisters made from the blacksmith's shop, the chain lock rudder, etc.

It was also very soon, because in his previous life, he was familiar with hot air ballooning, loved it very much, and often went to play, so he was familiar with it, and after a busy job, he finally assembled the first hot air balloon of this era, which was really a historic moment!

After the assembly was successful, under the excitement, he directly began to ignite and inflate non-stop, adding the butter sent by Xingwangfu to the oil tank, ready to really experiment to see if the hot air balloon made of cowhide can successfully fly into the sky, and whether his bold plan is feasible or not.

And looking at Wan Xing, who was anxiously working in the courtyard, with his efforts, the huge cowhide balloon began to ignite and inflate, inflating little by little, and Wan Chengdao stood aside, also full of excitement and apprehension.

"Son, is this really going to work? Inflate this cowhide balloon and it will fly into the sky, it won't fall down suddenly, why doesn't it look very safe, don't you lie to me? ”

He smiled happily, looking at the cowhide balloon that was gradually inflating in front of him, and fortunately smiled too.

"Of course Dad, it's definitely possible, just like Kong Ming lanterns, you've seen it, so don't worry, at least a hundred times more reliable than your rocket flying, just wait for the experience with peace of mind, I promise, it's fun."

Hearing this, although the matter is coming, Wan Chengdao is somehow getting more and more nervous, so he is still worried.

"Son, having said that, it's not that Dad doesn't believe you, but you have to know that this Kong Ming lantern is very light, it's still made of paper, it's small and light, and it doesn't drag any heavy objects, of course it's not difficult to fly."

"But your cowhide balloon is different, it's very heavy, there is such a big hanging basket underneath, and there are people in it, you said you have to load four or five, this is so heavy, can it really fly?"

Including Liu Quan, the steward of the Xingwang Mansion on the side, he was also a little worried.

"Yes, Childe, and is this really safe? You must know that although the Kong Ming lantern can fly into the sky, it is also very easy to burn, and if you don't pay attention to it, it will be ignited and fall from the sky, you must know that there are countless things that have ignited the people's houses, including the mountains and forests, because of the fall of the Kong Ming lantern over the years, in case your cowhide balloon is also ......."

As he spoke, he couldn't help but glance at him, and Liu Quan became more and more worried.

"After all, you also know that the prince is now a daughter, and at this critical moment, his safety cannot be wronged."

Hearing their worries, Wan Xing looked helpless at the same time, so he had to patiently explain to his old man first.

"Okay Dad, you just believe me, why can this Kong Ming lantern fly into the sky, do you know?"

Hearing Wan Xing say this, Wan Chengdao was also stunned, because he really never thought about this question, so he couldn't help but scratch his head and said, "Yes, why?" Son, you know what?

I saw that Wan Xing said with a smile: "That's not it, Dad, you don't even know the principle, isn't it unfounded to worry about the sky, what are you worried about, this is first of all, the reason why Kong Ming lanterns can fly into the sky, you have to understand, is not simply relying on the relationship between light and heavy, but related to air quality." ”

"Air has mass?"

"That's right, in short, the air we live in has mass, and its mass is not fixed, but can be artificially changed, as long as the air quality is smaller than normal, it can fly, and the easiest way to change it is temperature."

"How to put it, it is the same volume of air, if the temperature is different, their density and mass are also different, this is like the relationship between water and ice, although they are essentially the same thing, they are all water."

"But when the water freezes, it becomes less dense, so when we press the ice to the bottom, it always floats up, and that's why."

"And we use the same principle of hot air balloon flying, as long as we heat the air inside the air bag, then the air inside it will become less dense and the mass will be lighter."

"It will be significantly lighter than the same volume of cold air outside the airbag, just like the ice cube in front of it floats to the surface, causing the airbag to float as well, so that the whole hot air balloon can gain buoyancy and lift into the air."

"Buoyancy?"

"That's right, it's buoyancy, we can also call this buoyancy lift, that is, the force that makes the balloon rise into the sky, such as the hot air balloon in front of us, I roughly estimated that the volume of its airbag is almost 2180 cubic meters, and at room temperature, the total mass of the air in the airbag is about 2670 kilograms."

"After we ignite and heat the air bag, the air inside it will expand and heat up, the density will become smaller, and the excess air will be discharged from the bottom of the balloon after expansion, and when the 2180 cubic meters of hot air in the bag reaches 100 degrees, its mass will become 2070 kilograms."

"It's 600 kilograms lighter than the same volume of cold air, which means that it generates 600 kilograms of lift at this time, so when we fly with it, as long as the total flight mass is less than 600 kilograms, we can take off smoothly, anyway, that's what it means, do you understand?"

Saying that, he didn't care if his father really understood or not, he was left to ponder on the side, and fortunately he turned his head to Liu Quandao, the manager of Xingwang Mansion who looked worried.

"And Steward Liu, please rest assured, you must know that this hot air balloon is very safe, there will be no major problems, it's a big deal that I will personally go to the flight experiment to show you later, after all, I can't joke with my life, right, you must know that I also have to accompany the prince into Beijing together."

Saying that, fortunately, he also walked up directly, regardless of everyone's opposition, he was really ready to try to fly in a hot air balloon and become the first big hero to take off from Wuhu in this era, maybe he could go down in history.

He really didn't worry too much, he was very confident, and he felt that he should be sure that there would be no major problems.

After all, the material used in his hot air balloon is extravagantly sewn from cowhide, although it is not the nylon fabric of the standard hot air balloon, but it is quite good, or even better.

Because cowhide is already elastic, after special nitrate treatment, it not only becomes very light and thin, but also has better air tightness and tougher texture, and is not afraid of scratches and scratches.

You must know that most of the armor in this ancient world was made of this kind of leather, so ordinary sword weapons, even bows and crossbow arrows, are difficult to shoot through the cowhide balloon he made, which further enhances its security and is not afraid of being destroyed.

It can be said that using it as a material to make a hot air balloon, in addition to being a little extravagant, is definitely the best choice in this era, which can better store gas, do not lose hot gas, and reduce the consumption of heat source.

And even if there is a problem with poor air tightness during the flight, such as a hot air leak or something, it doesn't matter.

Because the giant balloon will also act as a parachute-like effect, it will control the descent speed within a suitable range, rather than the kind that falls suddenly, which is enough for them to have plenty of time to react and cope, and there is not much of a problem.

So I came in front of this huge cowhide balloon with confidence, and watched it swell up and begin to float into the air gradually, but it was only tied to a rope that it didn't fly away completely, so that De Wanxing couldn't help but nod with satisfaction.

I thought it was not bad, it really floated up, it seems that the group of embroidery sisters really did not disappoint themselves, the sewing process in the middle of the cowhide balloon, there is indeed nothing wrong, the air tightness is very good, and it is completely usable.

Then, his eyes turned down, starting from the huge cowhide balloon on the top and going all the way down, and he saw that under the cowhide balloon, there was a gas stove-sized oil tank, which he specially asked Uncle Liu Qiang, the blacksmith who was familiar with his father, a total of five, one for each hot air balloon.

The oil tank is full of butter, which is carefully boiled by the chefs of Xingwangfu, and it is extremely combustible and has a strong continuous combustion, as many as fifteen barrels, each of which can almost supply the whole day of this huge hot air balloon flight.

Further down, there is a big hanging basket, which he also let the group of bamboo craftsmen carefully weave, the base is also made of wood, very strong, can accommodate seven or eight people, and does not seem to be crowded, tied by ropes, hanging under the cowhide balloon, very stable, even if you jump hard, it will not be broken, and the safety is excellent.

In short, everything is perfect, so that Wanxing is also quite satisfied, and I can't help but praise in my heart, it is really a masterpiece, I believe that there is such an artifact, it should be enough to shock the world and help them complete this flying plan.

Then prepare for Wuhu to take off, fly fly!

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