Chapter 574 [Three Updates] 574
In order to make it light and airtight, Liu Tan once tried to brush tung oil on ordinary fabric, and then made a scaled-down hot air balloon shape. The hot air balloon model was about one-fifth the size of a real hot air balloon.
But even so, it is not small.
After Liu Tan completed the main body of the hot air balloon, he took a look at the size and decisively decided to leave the palace - it would be bad if he did this in the palace and scared someone.
Similarly, he can't go out in the imperial palace or the prince's mansion. The prince's mansion is so close to Weiyang Palace, what's the difference between him going out and not going out?
Finally, he turned around and went to the Shiheyuan that Liu Che had given him - even though he felt that the manor was more suitable, but when he thought that he was really going to make it, he would definitely let Liu Che go and have a look. There were many workshops in the manor that Liu Tan had been working on that were still in operation, and the most numerous were probably paper workshops.
The environment is much worse than that of Shiheyuan. Anyway, hot air balloons don’t require a very large space, so we might as well do it in Shiheyuan.
It's a pity that the imagination is good. In fact, after the fabric is brushed with oil and turned into oilcloth, although it is indeed waterproof, moisture-proof and airtight, the most terrible thing is... it is more easily ignited than before.
Liu Tan originally wanted to give it a try, but ended up... almost burning Shi Heyuan!
This won’t work. It’s too dangerous. Even if it is improved, it’s hard to say how long it can last. What if the balloon catches fire while it flies into the sky? Wouldn’t that be fatal?
Liu Tan thought that the hot air balloon could be built, but he had to take safety measures, such as putting an inflatable cushion underneath, so that if it fell, there would at least be some cushioning and it would not hit the ground directly.
Oilcloth cannot be used as the main body of a hot air balloon, but it can be used as the material for an inflatable cushion, so Liu Tan put it aside as a backup.
As for the choice of material for the balloon, Liu Tan thought for a long time and finally decided to use leather.
Animal skins are soft enough, and sheepskin is also thin and light, so sewing hot air balloons should be no problem. At most, it will require some processing.
However, even a hot air balloon that is only one-fifth the size requires the skins of more than ten sheep - after all, sheep are not big in size, and not all the skins of their bodies can be used.
As for why he didn't use cowhide... Liu Tan was worried that he would be criticized as soon as he used cowhide.
In the Northern Border Kingdom, cattle are not precious animals, and most people even have the habit of eating beef. However, this is not allowed in the interior of the country, and the Northern Border Kingdom cannot supply beef to the entire Central Plains. At most, it can radiate to the surrounding areas, or transport the freshest and tenderest beef to Chang'an. Therefore, it is basically a deeply rooted idea that cattle cannot be slaughtered casually.
Liu Tan had thought about using pig skin before, but these days there are fewer people raising pigs than sheep. After the sheepskin is peeled off, the mutton and other things have a place to go, but pork can only be sold to civilians, or in other words, the pork of adult pigs can only be sold to civilians.
Suckling pig... If we really want to use suckling pig skin, how many suckling pigs would we need?
But in fact, even ordinary people don’t like to eat pork, because pork has a smell and is not cheap. It takes too much food to raise a pig, and there is no feed these days.
Liu Tan had thought about studying how to process pork before, but later he realized that even if he figured out how to make pork tasteless, not many people would raise pigs because the conversion efficiency was too low. Compared with chicken and duck, the price of pork would inevitably be relatively expensive, and ordinary people would still not be able to afford it. The nobles... the nobles generally ate suckling pig.
This means that he can only use sheepskin to make hot air balloons.
Piles of sheepskins were transported to Shiheyuan. The next thing to study was the sewing technology. The threads used were the strongest hemp threads. The craftsmen sewed them bit by bit according to the shape given by Liu Tan. Because it was all handmade, it took a long time.
Liu Tan left these matters to his subordinates to take care of, while he himself needed to study a very important thing - the power system of the hot air balloon.
The so-called power system is actually the ignition device. Because this hot air balloon is the simplest one that uses the principle of hot air levitation to achieve the purpose of taking off, the ignition device and heater must be above the manned part and below the hot air balloon.
Liu Tan chose artificial petroleum as the fuel, so he had to ensure that the power system was stable enough to avoid oil leakage during flight. If it was just oil spilling, it would be fine, but if sparks splashed, there would be no other way but to wait for death - where could he find something to put out the fire in mid-air?
There were no fire extinguishers in those days. Even if Liu Tan knew what a fire extinguisher was, he couldn't make one because the technology didn't allow it!
The first is the oil tank for storing artificial petroleum. The oil tank must basically be made of metal, but at the same time it must be able to withstand high temperatures, or have poor thermal conductivity, so that the flames burning above cannot affect the oil inside and cause the tank to explode.
It would be better if the burning part was farther away from the oil tank, but that would cause a problem with the oil supply.
Liu Tan thought for a long time and finally divided the oil tank into two, making it into a triangle shape with the burning pool. The burning pool was at the bottom, and the oil tank was supported by an oil pipe at both ends, which was a little further away. Then a simple mechanism was made in the burning pool. When there was enough oil inside, the place where the oil pipe connected to the burning pool would be blocked. As the oil burned less and less, the plug blocking the oil pipe would rise little by little, and the oil inside would be injected into the fuel pool. The fuel pool would then sink again, blocking the oil pipe.
This mechanism is actually very simple, and he can do it without the help of the Mo family.
But whether it works or not still needs to be tested.
Seeing him toiling away on this thing for days, Miao Rui couldn't help but feel distressed and asked, "Your Highness, why don't you give orders to the Mo family disciples or the Gongshu family to do it?"
Liu Tan explained, "This is more important than a telescope, and its principles can't be easily revealed to others."
Of course, the main reason why he could let Mo Jiu and Gong Shuchuan do the telescope was because neither the Mo family nor the Gong Shu family had mastered the method of smelting glass, and the most important thing about the telescope was the smelting of glass.
So even if they knew how to make a telescope and the principles behind it, they would not be able to make it if they did not have the right glass.
A hot air balloon may sound much more complicated than a telescope, but in reality, making one requires more time spent on materials. If technology is not an obstacle, it will be very easy to copy.
The impact of a hot air balloon should be greater than that of a telescope. How to use it at that time depends on Liu Che's decision.
Of course, there was another small reason that Liu Tan did not say out loud - he made this hot air balloon to compete with that great witch from Baiyue, in order to suppress him and prevent him from making messy and weird things for his father. If it was just a simple sacrifice, it would be fine, but if he made some messy things for Liu Che to eat, what if he died after eating them?
Therefore, this thing must remain mysterious to a certain extent, at least to prevent the great wizard from figuring out what it is used for.
After the heating device was completed, the airbag part was also sewn, and the hanging basket was already completed.
The next step is to assemble the airbag, heating device and hanging basket.
The heating device was placed on top of the hanging basket. Liu Tan calculated the distance and directly chose to use eight copper pipes to connect the oil tanks at both ends, four on each side. These four were then merged into one and placed on both sides of the hanging basket. A door and stairs were set up at the back of the hanging basket for going up and down.
As for the hot air balloon, the basket was temporarily connected with an iron cable - Liu Tan really couldn't find a light rope. The most feared thing about this thing was probably that the rope was not strong.
Fortunately, this was just a miniature hot air balloon. After everything was loaded, Liu Tan asked someone to ignite the heating device and then cover it with the airbag.
Because there is not much air in the airbag at the beginning, it can only be supported with special things.
In Liu Tan's impression, once the hot air balloon's heating device is ignited, it should be able to take off quickly.
However, the reality was that he sat next to it and waited until he was almost asleep before the airbag gradually inflated and began to lift off the ground extremely slowly, little by little.
When they saw the hot air balloon start to take off, Miao Rui and Bigo couldn't help but hold their breath, staring with wide eyes as they watched the hot air balloon rise little by little.
At this time, the hot air balloon was still tied to the ground with ropes. The person guarding the ropes began to loosen the ropes little by little as the hot air balloon rose after noticing that the hot air balloon was gradually rising.
However, when the hot air balloon basket just rose above Liu Tan's head, the balloon stopped rising and remained at that height from then on.
Miao Rui and Bigao stamped their feet anxiously: "Promotion? Why not promotion?"
Liu Tan was very calm. He was used to it anyway. It would be a surprise if he could make something smoothly.
He looked at the flame, which was not weak, but seemed not strong enough compared to the airbag. However, the problem was that this heating device was already the largest in proportion. If it were any bigger, it probably wouldn't even be able to rise to a height of one person.
Liu Tan thought about it seriously for a long time, and finally remembered that the heating device in the future... seemed to have a blower.
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