Emperor Xiaoyao of Tang Dynasty

Chapter 365 Argument Concerning Hot Air Balloons

For the accuracy of the data, the doors and windows are all open, try to move the brazier once, try to avoid the lift error caused by the temperature rise around the brazier.

Cheng Huaimo was honestly doing the work of the recorder, but his posture was not very elegant and beautiful.

After many experiments, after successfully igniting three large lampshades, the data came out, and the buoyancy brought by one cubic meter of heated air floated around 180g.

In order to prevent the volume of white paper from becoming larger under the pressure of heated air, Jinyu asked craftsmen to increase the amount of bamboo strips on each side when making large lampshades to glue the paper firmly and shape it.If the amount of bamboo strips was reduced, the large lampshade might be able to fly.

"If some bamboo strips are taken out, wouldn't the lampshade be able to fly?" Cheng Huaimo looked at the data on the paper, pointed to the lampshade and said excitedly, because he was too excited, he rubbed against the wound, and then yelled .

"Well, as long as the buoyancy is greater than gravity, you can fly." Jin Yu nodded affirmatively, it's not bad to be able to draw inferences from one instance.

"As long as the lampshade is made big enough, can it fly with people?" Qin Huaiyu was also very excited, looking at Jinyu excitedly.

"Paper paste is not good, small ones can still be played with, and a little bigger ones will be blown to pieces by the wind. Today we are going to demonstrate how big a volume can be made to fly, and what kind of fabric is suitable." Jin Yu pointed to the few corners of the wall. A piece of cloth said.

"Listen to the elder brother's assignment!" The two strong boys were full of interest, flying to the sky!Are there any little fairies in the sky?
As for whether the imperial court will let Fei... It's not done yet, it's just an argumentation stage, let's talk after the argumentation is over!

"I told you before that the surface area of ​​a sphere is the smallest under the same volume. Let's use the sphere to demonstrate that a balloon with a larger diameter is needed to send a person into the sky. Do you remember the formula for calculating the surface area and volume of a sphere?" The two nodded. , Jinyu continued, "The product of the volume of the ball and the buoyancy per unit volume is the total buoyancy, the area of ​​the ball multiplied by the weight of the cloth per unit area is the weight of the ball, and the former minus the latter is the theoretical weight of the balloon when it can fly. Maximum weight. If you want to fly with people, let’s set the weight at 100kg for the time being.”

Jinyu took out a piece of paper, wrote it over and over again and said: "Assuming that the weight of a square of fabric is Xkg, the formula should be: 4/3πr*0.18-4πrX=100, π is 3.14, and it is simplified to 0.18r-rX=what ? Let me do the math, emm..."

……

"23.886! It's been a long time, but it's a bit rusty." Jinyu put down the pencil, "Then let's calculate the radius of the balloon according to 0.18r-rX=23.886. X needs us to demonstrate what kind of fabric to use first, and determine the fabric. Determine the weight."

"Well... this factorization is a bit tricky." Cheng Huaimo lay on his stomach and scratched his head.

"Well, why don't we change our minds?" Qin Huaiyu also raised his head.

Change your mind, in the boudoir, you and your wife often change your mind... But when the words came out of Qin Huaiyu's mouth, why didn't they sound that way?Don't be awkward, get a layer of goosebumps.

"That's called changing your mind!" Jin Yu rubbed his arms, feeling less uncomfortable.This kind of factorization above should be left to interested book friends. "Huaiyu, help me take out a piece of paper, let's use a more intuitive method to verify."

The paper was produced in Zhuangzi’s Shang workshop. In the past, the owner of the workshop produced rice paper, which was mainly used for printing, and the ink bleed effect was not ideal for writing brush characters.Writing with a brush is still the mainstream nowadays. As a dignified royal joint venture, we must have a specific sense of responsibility, expand the production line, take advantage of production capacity, and force other workshops to improve papermaking technology and lower sales prices. This is all negotiated before, so now The types of paper produced by workshops are no longer single.

The paper was purchased by Jin Yu in the name of office use, to practice big characters for himself, because a while ago, his daughter-in-law even said that the brush calligraphy he wrote was crooked and ugly!It's far worse than Bai Ze's handwriting!This is really something my aunt can bear, but my uncle can't bear it either!practice!Must practice!Practice four words first: "agree" and your name!Now that I have become the principal, these four words should be written in a flowing manner, with iron hooks and silver paintings!
Most of the commonly used paper these days has raw edges, different sizes, and can be cut casually, but there is one thing that works: on the knife!Knife is a quantifier unit. A knife is rolled together and pulled out when used. It is a bit troublesome to operate by yourself.

"Then tentatively use three rules for the radius of 3 meters, 5 meters, 7 meters, and 9 meters to calculate, or the form is more intuitive." With Qin Huaiyu's assistance, Jin Yu quickly drew the form, filled in the header, and calculated respectively Fill in the surface area and volume, and a simple form is ready.After the weight per unit area of ​​the raw materials is determined, the above factorization is handed over to interested book friends to relieve boredom (manual funny face).

"Next, let's discuss what kind of fabric is suitable for the airbag. The airbag should be well sealed, as far as possible not to leak air, and it should be as light as possible, and it must be able to withstand strength. I have seen most of the fabrics on the market. However, these three kinds of fabrics may meet the requirements." Jin Yu pulled out a piece of silk, silk, and cotton each, "Huaiyu will help spread it out, Huaimo is injured and don't move."

"The silk is not suitable, right?" Cheng Huaimo's buttocks were injured, but the strength of his hands remained the same. He grabbed the silk cloth with both hands and pulled it, "It's so out of shape that if you sew it hard, the needle eye will leak air. Besides, this silk cloth It is not resistant to making, and it will get silky if it is slightly scratched."

"That's right, keep talking." Jin Yu encouraged.

Cheng Huaimo stretched out his claws to tear it again, covered his face and blew hard, um, poor elasticity and poor air permeability. "Except for the key point and being more expensive, the silk cloth is quite suitable in other places." After speaking, he laughed and rubbed the silk cloth on the back of his hand... The obscenity is gone.

"Huaiyu, what do you think?" Jin Yu ignored Cheng Huaimo's wretched behavior and looked at Qin Huaiyu beside him.

"Brother, do you want to use it a few times when you make this balloon, or as long as possible?" Qin Huaiyu twisted the cotton cloth with his hands, and after hearing Jin Yu talking to you, he moved his eyes from the paper and asked.

"Of course it will be used for as long as possible. Although we haven't counted the cost of labor and materials, but such a thing must be invested in a lot." Jin Yu glanced at Qin Huaiyu, did he regard himself as a prodigal?

"In this case, in my opinion, cotton cloth is more suitable." Qin Huaiyu put down the cotton cloth in his hand, got up, paced, and said slowly.

"Why do you say that?" Jin Yu asked.

At this time, Qin Huaiyu had already walked behind Cheng Huaimo, and with lightning speed, pointed at the back of Cheng Huaimo's neck with one finger.

After the slight "snap" sound, Cheng Huaimo stood up cleverly, and the momentum was so violent that he touched the wound. He gasped, pointed at Qin Huaiyu and said angrily, "You actually sneaked up!"

　[Note: There is no Kongming Lantern in Zhenguan and before, and the previous article related to Kongming Lantern has been adjusted.The date of the earliest appearance of Kongming Lantern is still uncertain. Personally, I think it is a bit far-fetched that it first appeared in the Three Kingdoms (The Romance of the Three Kingdoms is a novel, not a real history). After all, papermaking technology could not support this invention at that time.My personal preference is that Kongming Lanterns were invented by Shen Qiniang of the Five Dynasties. The reason is that papermaking in the late Tang and early Song dynasties had a qualitative improvement, and the time coincided. 】

　　
　
(End of this chapter)