Chapter 1801

They nodded vaguely.

Seeing this, Zhang Feng continued, "but the effect of this coarse cloth is not very good. It's too easy to breathe. You can try new materials next time."

"Teacher, what materials should be used?"

Ma Zhou asked subconsciously.

Hearing the speech, Zhang Feng paused.

Future hot-air balloons are basically made of reinforced nylon or polyester. These two materials are relatively light and strong. The most important thing is that they are airtight, but they are not available yet.

Although coarse cloth can be used temporarily, its air permeability is too serious, so it must be replaced with another material.

But he was baffled by what he changed.

Ma Zhou and Hao Chujun stood aside and did not dare to say anything for fear of interrupting their mentor's thinking.

After about a quarter of an hour, Zhang Feng smiled and said slowly, "change to silk."

"Silk?"

Ma Zhou and Hao Chujun looked at each other and made a sound almost at the same time.

Because they all know that silk is very expensive in the Tang Dynasty. Generally, only large families have money to use it. Now my mentor says to use silk. Where can I get it?

It seemed that Zhang Feng saw their embarrassment and smiled, "don't worry, I'll get this for you."

In fact, he wanted to change a material for a long time. He just thought of silk before he said it.

Silk has good moisture absorption, UV resistance and heat resistance. Under the maintenance of these characteristics, hot-air balloons can operate normally in hot or rainy days.

Although it's a little expensive, it's still worth a try. After all, research is to find a right method among thousands of wrong methods.

Seeing that Zhang Feng said so, it was no longer easy for them to say anything. Qi Qi nodded: "yes, mentor."

"Not only these, you can also try to change other experimental equipment."

Zhang Feng glanced at them and said.

Now, although the hot-air balloon has taken off, it still needs the help of wind. We must constantly try other material experiments and update.

"Yes, teacher, students understand."

The two arched back.

Zhang Feng nodded with satisfaction. He was still very satisfied with the two disciples and had a good understanding. I believe he will live up to his expectations.

"Now that you all understand, I'll go first. If you have any questions, come to the academy to find me."

He glanced at them and was very pleased. Then he walked towards the door of the laboratory.

"I'd like to send you my teacher."

They said in unison.

"Don't send it. I can't find the way."

Zhang Feng waved and didn't care.

Ma Zhou and Hao Chujun were stunned. They knew that their mentor was not a sour Confucian who was rigid in etiquette, so they didn't care. They stood in place and looked like a compliment.

Zhang Feng smiled faintly and walked to the door alone. It seems that the appeasement has had a good effect. They also look like being taught with an open mind.

He was thinking about silk all the way. Nowadays, silk in Datang is more expensive than gold. It's a little difficult to do, but coarse cloth is really not a long-term solution and it's easy to leak. It seems that he needs Chumo's help.

Without a word, he returned to the Academy in less than a moment. At this time, it was the end of class. The Academy was full of laughter. There were several loud shouts from the basketball court. The leisure students walked in the Academy. When they saw Zhang Feng, they came forward to say hello.

"Hello, Dean."

"Hello."

Zhang smiled and continued to walk to his residence.

But when he passed the basketball court, a sad sigh attracted his eyes.

I saw a group of people around the basketball court, wearing short sleeves, as if talking about something.

Curiosity tempted Zhang Feng to walk over. He looked at the crowd and asked, "what are you doing here?"

Hearing the speech, everyone turned their heads together. At a glance, it was Zhang Feng. They quickly stood up and said respectfully, "Hello, Dean."

Zhang Feng nodded and continued to ask, "what are you talking about here?"

The people bowed their heads. You look at me, and I look at you as if it were hard to say.

Zhang Feng was a little disgusted and swept up an acquaintance in the crowd: "Yun Ping, what's going on? Don't grind like a woman."

"This..."

Yun Ping hesitated to look at the crowd. At last, he said slowly, "Dean, it's like this. After class, we played with another team of the college. It's unexpected that we lost..."

At this point, he paused with a blush on his face.

"And then? Go on."

Zhang Feng hurriedly urged him. When he was listening to his enthusiasm, the boy stopped talking. I really doubt whether this guy is deliberately trying to tempt himself. He has to clean up in the future.

"Later, we all refused and agreed to fight later. Now we are not here to discuss tactics."

Yun Ping has some grudges. When he speaks, he still doesn't look back at his companion. It seems that he is saying that you did it all. Now he has been caught by the dean.

Like a little quail, he lowered his head tightly and waited for Zhang Feng's punishment. So did the people behind him, as if he was afraid of Zhang Feng's punishment.