Genius is just the threshold for me!

Chapter 12 Small-capacity turbofan

"Foreign trade version."

Cai Wei replied earnestly, "An elder in my family is in charge of this part of the business and can get some spare parts at an internal price, but we need to send a letter through Chengdu Aircraft Industry Group's laboratory."

"No problem, I'll handle the correspondence, and I'll cover the cost!"

Lin Dong nodded decisively. Although it was an export-grade avionics equipment, it was still military-grade equipment, far exceeding the equipment he could collect.

With these factors in place, there is room for the next technological upgrade of model airplanes.

As for funding...

He checked the bank card Zhang Xiali gave him last year when he had a spare moment, and the seven-figure sum was enough for him to do whatever he wanted for several years.

"These are the books and papers I selected that are both theoretically sound and easy to understand."

Lin Dong switched computer interfaces and, almost without thinking, found more than forty papers to print. Then he took out five books on aerodynamics and fluid mechanics from the bookshelf.

He numbered all the books and papers and slammed them down in front of Cai Wei: "Books are the foundation, papers are the advanced level."

You should read through the books within twenty days according to the assigned numbers, and then read the corresponding paper after finishing each book.

"Twenty days?"

Looking at the five books, each thicker than a brick, Cai Wei began to question the meaning of life.

With such an exaggerated thickness, even a novel would be difficult to finish in three days.

Not to mention the specialized knowledge in aerodynamics and fluid mechanics.

"Yes, twenty days. You don't need to read it page by page. The key is to understand and thoroughly grasp the knowledge inside."

"Of course, you can also complete it in one summer vacation."

Lin Dong nodded and said calmly, "However, don't you want to design and build a canard-configured subsonic dogfighting model aircraft to participate in competitions?"

What?

Cai Wei's eyes widened, staring at Lin Dong with disbelief...

He originally thought that learning the aerodynamic layout of canards was already outrageous enough, but he didn't expect that after Lin Dong agreed, he would raise his requirements by eight levels.

Design a subsonic dogfighting model aircraft with a canard configuration to participate in a model aircraft competition?

He's still a freshman.

Not Bo Yi.

Are they sure this is something they can accomplish?

"Model airplanes aren't real fighter jets, so they're not that difficult. There are three of you, so if you work hard this summer, that should be enough."

Lin Dong pointed at Wang Rui, who was immersed in the sea of ​​knowledge: "Imagine that when everyone else has conventional wings, you have canards; when everyone else has model airplanes, you pull out a dogfighting model airplane and use aerial scalpels to cut down your classmates' model airplanes one by one. Wouldn't that open up the channel for direct admission to graduate school and doctoral programs?"

Holy crap!

Cai Wei's mind was filled with the imagery Lin Dong had described... This really got him excited! What to do!

"Can we really do it?" Cai Wei swallowed hard, looking at Lin Dong with some excitement.

"Aren't you guys helping to build one of these model airplanes right now?"

Lin Dong said calmly, "You can learn while helping out, combining theory and practice. By the time my model airplane is finished, I believe you will have learned enough."

"That's right."

Cai Wei paused for a moment, then exclaimed excitedly, "Alright! Twenty days it is! Let's give it our all!"

"Good job, then you can go read your book now."

Lin Dong nodded: "If there are any problems with Zhang Yue's processing and production, please keep an eye on it for me and combine theory with practice."

"Understood, thank you, Dong Shen."

Cai Wei, carrying the book, walked confidently to the side and began to immerse himself in the learning process.

Seeing Cai Wei and Wang Rui's focused expressions, Lin Dong nodded in satisfaction.

As expected of college students, their passion is undeniable.

Zhang Yue will be in charge of the manufacturing process, Cai Wei will provide technical guidance for the fuselage and aerodynamics, and Wang Rui will provide technical guidance for the aero-engines...

He only needs to complete the design work and solve a few problems that the three of them can't figure out or understand, and the subsonic combat model aircraft will be done.

"It feels great, my workload has been reduced by more than half."

Lin Dong stretched and continued to refine the details of the fuselage aerodynamic design, as well as the design of the aircraft engine.

As his first model airplane, Lin Dong still had some aspirations.

The fuselage adopts a canard layout, so the engine must be a low-bypass turbofan engine, and it must be a twin-engine configuration.

Over the years of development of jet aircraft, there are only four types of aircraft engines that are relatively common.

—High bypass ratio turbofan, low bypass ratio turbofan, turbojet, stamping.

High bypass ratio turbofans are mainly used in civil aviation or transport aircraft. They are primarily fuel-efficient, but their maximum speed cannot exceed the speed of sound. They are technically challenging and require long-term stability.

The low-bypass turbofan engines used in fighter jets have a high degree of thrust and speed, and are suitable for the transonic range of Mach 0.8 to Mach 1.5. They are technically very difficult to manufacture and require a balance between performance and speed.

There were also turbojet engines used in early fighter jets, which focused on maximizing efficiency at high speeds above Mach 1.5, minimizing pollution below the speed of sound, and had the lowest technical difficulty.

The last one is the ramjet engine, which is mainly used in missiles or high-speed reconnaissance aircraft. It is designed for extreme high speeds and has no compressor fan blades. It uses the intake pressure brought by the ultra-high speed to directly ignite the fuel. It has the most demanding requirements for the high temperature resistance of materials and structural design.

Currently, apart from simple electric ducted engines, most unmanned model aircraft use turbojet engines.

The advantage of this type of aero-engine is that it has low technical difficulty and is easy to implement.

Even video bloggers who repair motors can switch careers and become tech bloggers by learning to build turbojet engines by hand after a period of self-study, which is very suitable for aircraft enthusiasts.

However, the drawback of this type of engine is that it has extremely low efficiency and weak thrust at low speeds.

Model airplanes can only fly a few laps before needing to be refueled; they're either on their way to refuel or en route to refuel, and they produce black smoke without needing smoke generators.

Lin Dong has now replaced his model aircraft with a low-bypass turbofan engine, which improves the problem of low efficiency and weak thrust in the low-speed range of ordinary model aircraft using turbojet engines, ensuring the maneuverability of the model aircraft and the space for future supersonic upgrades.

However, the downside is that the technology is quite difficult, the internal temperature and pressure of the engine are very high, and the requirements for material properties are quite stringent.

Fortunately, I still have some reserves.

Thinking of this, Lin Dong pulled open the computer desk and laboriously took out a rusty metal blank.

This was a Children's Day gift from Lin Weiliang, who heard about his plans to design and build model airplanes during the summer vacation.

A blank of nickel-based alloy.

It is said that this was leftover material from the production of a certain experimental engine in the early years. The stress inside the blank has been released after shaping, and it is the optimal natural release.

The aircraft engine parts manufactured in this way are guaranteed to remain free of minor cracks even when operating in harsh environments.

"With this size, after removing the outer casing and combustion chamber, two more blades can be made, which would be perfect for a high-pressure turbine..."

Lin Dong took out calipers and measured the dimensions, then began to calculate and design based on the materials.

A low-bypass turbofan engine is divided into components such as intake, compression, combustion, turbine, and exhaust based on its process and function.

The compressor is further divided into low-pressure and high-pressure, and the turbine is divided into high-pressure and low-pressure.

Because the pressure and temperature increase from the intake to the turbine, the requirements for materials also become more stringent.

The outermost intake turbofan needs to be resistant to centrifugal force and protected against bird strikes, so titanium alloy is a normal choice.

Low-pressure compressors have lower requirements and can be made of stainless steel.

However, when it comes to the high-pressure compressor section, because it needs to withstand the enormous gas compression force, it has to be replaced with titanium alloy again.

Due to the extremely high temperatures of combustion, the combustion chamber typically requires a high-temperature resistant nickel-based alloy, along with a heat-resistant coating.

The high-pressure turbine, which is directly connected to the combustion chamber, must withstand not only the high temperature of combustion but also the enormous pressure of gas combustion and expansion. The minimum requirement is a nickel-based high-temperature alloy, while high-end fighter jets require polycrystalline or single-crystal materials.

"Materials, the eternal shackles of human technology..."

After finalizing the design specifications and measuring the blank, Lin Dong set it aside, picked up the mouse and keyboard, and confidently began typing rapidly.

One by one, structural diagrams of compressor blades, turbine blades, intake turbofans, bypass components, turbine shafts, combustion chambers, and other components began to rapidly take shape on the computer...