Chapter 470 Back to the old problem
Sitting on a chair, two comrades next to me were talking quietly.

"You think this thing won't fall down?"

"Go away, can't you say something nice?"

"Comrade, we must not be feudal and superstitious."

"Even if you don't believe in feudal superstition, you can't make yourself unhappy, right? Really."

Gao Zhendong listened and said with a smile: "It's hard to say anything else, but this plane is really not that afraid of falling."

If a plane falls, as long as it does not disintegrate or directly crash, there are several possibilities.

It either glides to the ground without power, stalls, or goes into a spin.

But this flying tractor is not afraid of these situations at all.

This thing has extremely strong gliding ability and excellent low-speed performance. The speed required for gliding is very low. Even if it has no power, it can still glide slowly and find a place to make an emergency landing. There will be no problem.

It is also difficult to make it stall. Its low-speed performance is so good that there is no minimum take-off speed in its parameters. According to unreliable information, it is 45km/h, which means that an excellent cyclist can take off at the speed they pedal. In windy days, it is not impossible for it to take off on the spot.

The take-off and landing distance of this aircraft is no more than 200 meters, and it is also a proper transport aircraft, which is quite amazing.

There was a famous scene. The plane flew in the air for a long time, and when it saw the landmark, it did not move. The flying speed and the headwind speed canceled out... canceled out...

As for what to do if the aircraft really stalls or goes into a spin for any other reason, well, the tutorial for how to recover from a spin is roughly written like this.

"Let go! Take your feet!"

In other words, as long as the altitude is a little higher, if you let go of the joystick and don't pedal the rudder, the plane will automatically correct its tailspin. Isn't it amazing?

This is the reason why it is still in use after decades. It is very popular due to its simple structure, low cost, good safety, low operating cost and good load capacity.

Don’t worry about whether it’s noisy or not, just tell me whether you can get there or not.

Gao Zhendong roughly explained the advantages of this aircraft to the two comrades who were accompanying him. The two comrades were stunned. It seemed that Chief Engineer Gao knew everything.

This reminded Gao Zhendong of the feeling of bragging about his equipment to his desk mate in high school. His desk mate just stared at him with a pair of big, blinking eyes, as if to say, "I don't want to understand at all, but I really like listening to you talk about it."

It’s a pity that there are two grown men in front of me. Once they are gone, they can’t come back.

The tractor flew in the air for several hours. Gao Zhendong and the comrades in internal security were fine, but the comrade who was engaged in mechanics vomited a lot. Unlike the civil aircraft in the future that could cruise in the stratosphere above 4500 meters, the practical ceiling of the flying tractor was only meters, which was right within the range of more intense atmospheric activity.

I was already shaking, and then the wind blew on me. I couldn't describe how painful it felt.

I wonder if this comrade who works on mechanics will brag about this matter when he returns, Gao Zhendong thought in a rather unkind way.

A few hours later, the plane finally landed safely at the airport on the outskirts of Changji City. To be honest, Gao Zhendong was not really worried about safety. Although this thing was uncomfortable, it was still very safe. He was just worried that if other comrades took it again, they might not be able to withstand it.

To Gao Zhendong's surprise, the people who came to pick him up were not comrades from the Northeast Institute of Optics, but several comrades from the local army.

The leader saluted Gao Zhendong and said, "Hello, Chief Engineer Gao. I'm from the local army. My last name is Zhao. I've been ordered to cooperate with your activities here." After that, he handed over his ID, which was taken by the comrade from the internal security of the Third Branch Factory.

Gao Zhendong didn't know where this order came from. This visit had little to do with the army's work, or it could be said that it had little direct relationship with the work.

But he still expressed his gratitude first. The internal security comrade also handed the documents back and nodded to Gao Zhendong.

Following the visitor, we got on a jeep parked outside the airport and headed straight to the Northeast Institute of Optics as Gao Zhendong requested.

When they arrived at the Institute of Optics, it was already past three in the afternoon. They were received by a comrade in charge of Gao Zhendong's optical system. His surname was Li, the same as that of Deputy Director Li of the Third Rolling Mill.

Gao Zhendong's idea was to cut the Gordian knot, finish all the things as soon as possible, and return to the capital, where there were still a lot of things to do.

However, according to convention, the comrades from the Institute of Optics still took them on a tour of the Institute of Optics, of course, only the part that could be visited.

Finally, Engineer Li took Gao Zhendong outside a laboratory and pointed to the laboratory and said, "Chief Engineer Gao, inside is the laser beam expansion optical system you want. It is now in standby mode."

Gao Zhendong was cheered up and, under the guidance of Engineer Li, he put on protective clothing and entered the laboratory.

The protective clothing is not to protect Gao Zhendong and others, but to protect the equipment, ensuring that no large amount of dust or other particles can enter the laboratory.

What caught Gao Zhendong's eyes was a slightly cylindrical metal object, which enclosed most of the optical system. There was an opening in the middle of the side, which was used to place the mask.

Gao Zhendong and the comrade in charge of machinery carefully examined the machine. The comrade from the Institute of Optics introduced it to them: "The working wavelength of this machine is 355nm, the optical modulation transfer function is about 0.63 in the ideal position, the optical path difference is less than a quarter wavelength, the numerical aperture is 0.029, and the magnification is 1." Gao Zhendong really didn't understand these. Apart from the working wavelength of 355nm and the magnification of 1, he didn't know anything else: "Engineer Li, what does this mean?"

Engineer Li didn't take it seriously. After all, he wasn't an optician: "This means his resolution is 9μm."

9μm? Gao Zhendong was immediately amazed. With this resolution and small deformation, a line width of 10μm is not a dream.

"Mr. Li, how about the deformation of the image?"

"It's very small. The maximum field curvature is within 15μm, the maximum astigmatism is around 7μm, the overall distortion is less than 1ppm, and the image surface non-uniformity is less than 2%. I think there is no problem with your requirements." Engineer Li smiled, and he was quite proud of it.

For this machine, Gao Zhendong required a projection diameter of about 160mm and a distortion of 1ppm, which means less than 1μm, which was completely sufficient for Gao Zhendong's idea.

Gao Zhendong laughed out loud: "Mr. Li, thank you so much! Thank you for your hard work!"

Li Gong smiled and said, "It's good that I can meet your requirements. It's getting late today. How about we continue with other specific matters tomorrow?"

Gao Zhendong nodded repeatedly in excitement: "Okay, I won't bother you today, we will continue tomorrow."

That night, Gao Zhendong tossed and turned, thinking for half the night.

The next morning, Gao Zhendong and his men arrived at the door of the laboratory early. Engineer Li was already waiting there. They changed their clothes and went in.

After Gao Zhendong went in, Engineer Li began to arrange for people to use standard masks to conduct a complete test. After all, although he said it yesterday, the complete test process had to be gone through for Gao Zhendong and others to see, which was considered as the acceptance by Party A.

While the experiment was going on, Gao Zhendong was looking at the indicators of the entire optical system. He wanted to see if he could achieve his idea.

As he watched, he frowned.

"Mr. Li, the light transmittance of this system is more than 30%?" Gao Zhendong asked.

He didn't feel comfortable saying "only more than 30%", which was a bit inappropriate.

Engineer Li showed a bit of embarrassment on his face: "Well, the wavelength of 355nm has entered the ultraviolet wavelength, and the transmittance is inherently poor. Coupled with the material, it is rather ugly."

The wavelength of ultraviolet light is 10nm to 400nm, with high energy but poor penetration. This is a bit like the alpha rays in radiation, which have the highest energy, but the most common alpha rays can be blocked by a piece of printing paper.

This transmittance is because the 355nm wavelength is relatively long and the penetration has not deteriorated to the bottom.

This made Gao Zhendong feel a little difficult. If the second step required miniature projection and the miniature optical system, the transmittance would be further deteriorated. Although that step required focusing, even now, the transmittance was already on the edge of danger. Increasing the laser power was not as simple as working miracles with great force. The higher the transmittance could be retained, the better.

Gao Zhendong couldn't say for sure, after all, it was barely enough, so he just asked, "What is the light transmittance of the current material?"

“400nm波长10mm透光率不小于99%，300nm波长10mm透光率不小于30%，这已经是增加了增透膜之后的效果了。”

Wow, it drops very fast. No wonder the data is so ugly. 355nm is definitely much better than 300nm, but there are multiple lenses in an optical system.

Gao Zhendong nodded and expressed his thoughts while watching the experiment.

"Engineer Li, can the resolution of this system be reduced to 5μm or even better in the second step?"

He wanted to give it a try.

After hearing what he said, Mr. Li shook his head.

"It's very difficult. This is our limit right now. Apart from other things, the processing cost is extremely high. If it is raised to the level you mentioned, our current manual processing method may not be practical even after optimization. The processing cost will be extremely high and it will be impossible to mass produce it."

Gao Zhendong was not intimidated: "If you don't care about the cost, what if you only want one or a few sets?"

Engineer Li's eyes lit up, then dimmed again: "Then processing is possible, but if we increase the speed further, our materials won't be able to support it, and it will still be meaningless."

"Materials? What materials?" Gao Zhendong got to the bottom of the matter.

"As for optical glass, we are currently using crown optical glass, and its parameters such as light transmittance and thermal expansion coefficient are not very good, which will either affect key indicators such as optical modulation transfer function or its environmental adaptability. Slight temperature fluctuations may cause performance degradation. Even the current ones have strict operating temperature range requirements."

Back to the old problem, materials.

Crown optical glass is not a brand, but a type of optical glass.

(End of this chapter)