Republic of China: Ace Pilot

Chapter 558 Large Aircraft Modification, World War II Lithography Machine, Ah Quan's Wife
The telegram sent by Bai Yunfei reads as follows.

The previous matter has been resolved; there is indeed a way to conduct preliminary surveys and create topographic maps of Yanchuan.

[We have a group of international fighters from Korea in our ranks. Some of them intend to return home to organize revolutionary activities against the Japanese invaders, which perfectly aligns with your plan.]

The original plan was to have them infiltrate a passenger ship bound for North Korea. Now we have a new suggestion: could you fly them to North Korea in a plane and conduct an airborne infiltration?

Fang Wen knew about the North Korean international fighter.

After the Korean Peninsula was annexed by Japan in 1910, a large number of Korean anti-Japanese patriots fled to China.

One of the men involved in the assassination attempt on a Japanese general organized by Wang, the leader of the Axe Gang, was a Korean.

After Shanghai fell, they retreated to Wuhan, where they established the "Korean Volunteer Corps." Their North China branch entered the Jin-Cha-Ji base area at the end of the year and joined the anti-Japanese war struggle in the base area.

Fang Wenzheng knew of the existence of this group of people, which is why he sent a telegram to Bai Yunfei.

Now that the results were in, Fang Wen immediately went to the telegraph office to send a reply.

[This plan is feasible. Have they received skydiving training?]

One hour after the telegram was sent, a reply was received.

Not yet. We're planning to arrange for him to receive skydiving training at the flight regiment.

Fang Wen felt it was better to train himself, as it would be faster that way, and once he was trained, he could immediately carry out the mission.

He then explained to Bai Yunfei that he would come over in two days.

The trip to the Jin-Cha-Ji base area was scheduled for two days later because Fang Wen needed to make arrangements for other work.

After sending the telegram, Fang Wen took Gong Xiuneng and flew the plane to the base in northern Myanmar.

Upon disembarking from the plane, Fang Wen went to the No. 2 Aircraft Manufacturing Plant to inspect the modification of the large aircraft.

He carefully observed the parts that had already been modified.

During this period of renovation, the aircraft's nose shell has been completely removed, and the internal keel has also been modified.

The original aircraft's wings and propeller were fixed together by steel cables, giving it a biplane-like appearance, but this has to be removed. The new aircraft's wings and propeller engine are now integrated.

After reviewing the documents, Fang Wen convened a meeting with engineers from each engineering team.

"I've checked on the aircraft's modifications, and things are going well so far. Maintain this condition, finish the wing modifications, and install the engines and propellers when I return. Are there any problems with your work?"

“Yes.” An engineer stood up and said, “The workload is too large, and the original design drawings of the F.220 are not complete and there are some inconsistencies with the existing design drawings. When we encounter these situations, we can only temporarily abandon the modification of those parts to avoid problems that lead to a complete rework.”

Fang Wen nodded: "Really? Take out the drawings of the problematic parts, let me take a look."

Immediately, the engineers produced several sets of blueprints.

These drawings are all in duplicate.

The aircraft structural diagrams provided by Falman Corporation, as well as the modification design drawings made by Fang Wen.

“Look here,” an engineer pointed to the markings on the drawing where the wing connects to the fuselage. “In the original drawing by Faleman, this area was reinforced with cross-cable steel cables, relying on the aerodynamic layout of the biplane to share the stress. But your modification drawing has removed this structure, keeping only the high-wing, and you also need to add two of our V12 engines at the wing root, which means that the original load-bearing nodes will have to withstand more than three times the tensile force.”

He traced an arc along the edge of the blueprint with his fingertip: "We measured the thickness of the original fuselage's aluminum alloy keel, and according to the stress calculations in the modification drawings, it needs to be increased by at least 2.5 times. But if we directly thicken it, all the rivet holes in this part will have to be redone. I think it's better to remove the wings and remake them."

Another engineer added, "There's also the tail fin linkage rod. The original design used a steel cable for traction, but the modification drawings changed it to a hydraulic push rod. However, the drawings from Falemand didn't clearly show the routing of the pipelines inside the tail section. We only discovered this after we disassembled the fuselage skin. There are three steering pulleys for the control cables hidden there. The hydraulic push rod simply can't be installed unless the entire tail fin frame is sawed off and re-welded."

Fang Wen picked up the two drawings, stacked them together, and examined them under the light. Faleman's original drawing had rough lines, marked "Drawn in 1932," and had traces of coffee stains on the corners; while on his modified drawing, the force arrows marked in red pencil were densely packed, forming a dense triangular area at the root of the wing.

“Regarding the load-bearing capacity of the steel cable,” Fang Wen suddenly circled an inconspicuous small square on the original drawing with a pencil, “there is a spare reinforcing rib interface here. We can widen it into a 10-centimeter square connector, and then make an adapter using chromium-molybdenum steel. Weld one end to the original keel and the other end to the load-bearing beam of the new wing—this way, we don’t need to change the original stress mechanism, and the wing’s load-bearing strength is sufficient.”

He then turned to the tail section: "The hydraulic push rod doesn't need to be installed where the original steel cable was. See this vent? Drill an 8-centimeter diameter hole here and pass it through. Fix the push rod diagonally to the tail wing strut, and use a gearbox to change the angle for transmission."

The engineers immediately bent down to take notes, their pens scratching across the drawings.

Fang Wen pushed the original drawing back: "Falaman's drawing only shows the visible structure. The hidden pipes and spare interfaces are the key. Those are not in the drawing. You should form a statistics team, number the old parts that have been removed according to their location, and make supplementary annotations based on the original drawing to avoid encountering similar problems next time."

But these are not enough.

The aircraft structural drawings provided by Falman Company contained a large amount of implicit data that was not recorded; they were only rough drawings. Fang Wen had to re-annotate the original drawings to make them match his own modification plans.

Then, for the next day, he spent his time annotating the original drawings of Faleman with various hidden parameters and components, covering the entire drawing with dense writing.

With his annotations, the engineers at Taishan had better guiding data for their future work.

Fang Wen instructed them to work carefully and not to worry about not having enough time. He told them to work slowly and meticulously to modify the large aircraft.

With the large aircraft modification arrangements completed, Fang Wen returned to the Taishan Research Institute.

He needs to write down his ideas about scientific research so that researchers at the institute can follow his line of thinking to conduct research and development.

The main focus is on the concept of integrated semiconductor chips.

Currently, Taishan Semiconductor Radio uses integrated circuit boards, making the radio much smaller than vacuum tube radios and achieving portability.

But this is far from enough.

Miniaturizing integrated circuits requires a breakthrough technology.

That was the breakthrough in semiconductor technology made by Fairchild Semiconductor, which is still building airplanes today, in the late 1950s.

That technology is called planar processing, which involves creating metal interconnects on the surface of a silicon wafer to achieve planar circuit integration.

That technology is better than existing semiconductor integrated circuit boards, but to realize it, another technology is required: photolithography.

This was the precursor to the now-famous lithography machine technology, though it wasn't that advanced back then.

Fang Wen happened to know the principle of this early photolithography technology, and immediately wrote it down on paper.

Photolithography, inspired by printing, achieves micron-level precision pattern transfer through photochemical reactions, enabling the fabrication of circuits on silicon materials.

Its principles have three main points:

Photoresist effect: This technique utilizes the chemical changes (crosslinking and decomposition) that occur in photoresist under specific wavelengths of light to "copy" a mask pattern onto the surface of a silicon wafer.

Selective etching: This involves using a chemical solution to remove areas not protected by photoresist, forming structures such as PN junctions and metal interconnects required for semiconductor devices.

[Diffusion doping: Injecting impurities (such as boron or phosphorus) into the windows formed by photolithography to precisely control the conductivity type and properties of the semiconductor.]

Therefore, photoresist is the core of this technology; everything else is achievable under current conditions.

So where does the photoresist come from?

This is something that Fang Wen knows about.

He wrote on the second sheet of paper.

Photoresist: Polyvinyl cinnamate

[Ingredients: Polyvinyl alcohol (PVA) (as a polymer backbone, providing film-forming properties and mechanical strength), cinnamic acid ester groups (grafted onto the PVA chain via esterification reaction, imparting photosensitivity), sensitizer 5-nitroacenaphthene (extends the photosensitive wavelength and improves the response efficiency to ultraviolet light)] The subsequent synthesis process is described in a dense and lengthy manner.

The preparation of polyvinyl alcohol (PVA) was completed by European chemists more than 20 years ago.

Adding an alkali (potassium hydroxide) to an alcoholic solution of polyvinyl acetate yields a resinous product, which is polyvinyl alcohol.

Cinnamic acid, on the other hand, can be prepared using the perkin reaction.

Cinnamic acid is then mixed with pyridine and an intermediate is produced at a certain temperature, which is then esterified with PVA.

The reaction solution was then poured into a large amount of methanol, causing polyvinyl cinnamate to precipitate out as a white flocculent precipitate, while unreacted PVA and byproducts dissolved in the methanol.

The precipitated polyvinyl cinnamate was modified into powder, and then cyclohexanone was used as a solvent to prepare a 5%-10% concentration of adhesive solution. 5-nitroacenaphthene (accounting for 1%-3% of the weight of the adhesive solution) was added as a sensitizer, and after stirring evenly, it was allowed to stand to degas.

This is the manufacturing process of photoresist.

One of the substances is 5-nitroacenaphthene, for which Fang Wen did not provide a specific production method.

However, it is not impossible. As early as 1834, German chemists had already separated acenaphthene from coal tar.

Fang Wen vaguely remembered that as long as acenaphthene was present, it could be added to glacial acetic acid, and after a series of chemical operations, 65% nitric acid was added. After stirring at 23-26℃ for one hour, 5-nitroacenaphthene could be generated.

But he didn't know what specific chemical operations were required.

This requires chemists at the Taishan Research Institute to conduct continuous experiments to find the correct results.

He then assigned the experimental work of producing 5-nitroacenaphthene, allowing the chemists at the research institute to focus on finding the substance he wanted.

As for the preparation of photoresist and the realization of photolithography technology, we'll have to wait until he returns from the north.

Two days later, Fang Wen prepared to head to the Jin-Cha-Ji base area.

Before leaving, he put two pieces of paper with the information about photolithography technology into a leather bag, got up, opened the door, and went to the archives room on the second floor to store them.

But then it stopped in front of the door.

He knew the importance of this futuristic technology and was determined not to let it be stolen by Japanese spies.

After all, who knows if there are still Japanese spies lurking in the base in northern Myanmar?

After hesitating for a moment, Fang Wen decided to find a new place to store his collection that only he knew about.

He glanced around the room.

His office was simply furnished, with a desk, a filing cabinet, and a leather-covered sofa for guests.

If hidden among these objects, they could still be violently destroyed and searched out if someone breaks in.

But there's one place you'd never expect.

That's the window frame.

Fang Wen walked over, opened the brown paper bag, took out two sheets of paper, folded them into a long strip, then pried open the window frame and stuffed the strip of paper into the gap in the window frame.

That's settled.

He burned the brown paper bag, turned around, and left.

The general manager left the research institute and went to the airport with Gong Xiuneng to fly away.

It was 6 p.m., and the research institute closed for the day.

Most of the researchers in the institute left the office building and went to the cafeteria for meals.

The cafeteria where they eat is separate from other departments, so they can be more relaxed when talking to each other than in public.

They ate and chatted at the same time.

"What are your thoughts on the fact that the general manager personally assigned this research task?"

"The process involves extracting acenaphthene from coal tar to create a new type of chemical. Once you have a direction for your chemical experiments, they are not actually that difficult."

"It still depends on luck. Sometimes you can find the substance you want in one go, and sometimes you have to try repeatedly without any results."

"Yes, that's how chemistry is."

Their conversation was overheard by a cleaning lady.

The woman swept along the ground, shoveled up the trash, and mopped the floor, working very diligently.

The cafeteria's chefs and staff couldn't help but sigh:

“Look at how she works, Quan can’t compare to her.”

"Ah Quan is so lucky to have such a capable wife. Even when he's sick, his wife can still help him with the work."

"The cafeteria has a rule that outsiders are not allowed to come. Will it have any impact if Ah Quan's wife works for him?"

"Go away, it's just sweeping the floor, it's nothing."

Their words disregarded the woman, prompting her to turn around and reply in a Hebei accent, "I'm just sweeping the floor, what's the big deal? Do you expect my husband to lose his job?"

Everyone burst into laughter and dispersed.

An hour later, the cafeteria closed for the day, and the staff began to clean up. After finishing their work, everyone said goodbye and left.

Ah Quan's wife also changed out of her work clothes and went home carrying a food box.

She returned to her single dormitory room, closed the door, put down the food box, and her simple and honest expression gradually faded, replaced by shrewdness.

The husband, A-Quan, walked over eagerly, bowing and scraping, and said, "You're back."

They didn't display any domineering behavior towards each other in public.

The woman ignored him, took out a box from under the bed, and took out paper and pen to write.

After she finished writing, she folded the note and handed it to Ah Quan.

"Tomorrow, go out under the pretense of buying medicine and deliver the note to the location I told you to go."

Ah Quan's forehead was sweating: "There's a hospital in the base, this excuse won't work."

The woman glared at Ah Quan, her face cold: "There are radio monitoring devices here. You can't send messages, but you must send out intelligence. Your illness is the best excuse. Tomorrow, make it look more serious. Say there's a miracle doctor in a village outside who can cure your illness. Remember, your family is in our hands. If they don't obey, they'll all die."

Ah Quan panicked: "I promised to help you, you can't go back on your word. In that case, I'll go out to deliver the message, but you have to let me see my family."

The woman looked at Ah Quan as if he were dead, then smiled and said, "Alright, after you deliver the letter tomorrow, I'll let you see your family."

(End of this chapter)