Chapter Forty-Six: The Combustion Chamber Is Complete

With the blueprints in hand, Yang Hui and Wu Dabo hurried to the factory assigned by the institute. The place didn’t even have a name, just a code, so no one bothered with such details.

They found the person in charge and explained their purpose, showing him the blueprints. Unexpectedly, the response was, “I don’t need to look at that; just go straight to the sheet metal workshop. What you’ve designed is a stamped part, but we’re only helping to make a prototype, so we won’t be making stamping dies. But it’s fine; your sheet metal workers can handle this.”

Thinking it over, Yang Hui realized the technical requirements for their part weren’t that high—making the combustion chamber by hand was feasible. After saying their goodbyes, they headed straight for the sheet metal workshop they’d noticed on the way in.

Even before entering, the distinctive clang of metalwork reached their ears—the unmistakable sound of the sheet metal shop at work. A man who looked like the workshop foreman was dealing with a defective part, though it seemed the issue was with the measuring instruments.

Once the matter was settled, Yang Hui approached the middle-aged man to discuss their business. The man was easy to talk to; after hearing Yang Hui’s request, he agreed immediately and led them to his cluttered office to look over the blueprints.

The office was a mess, papers and blueprints piled everywhere—some bound, some folded, some rolled up—evidence of the man’s busy schedule. He cleared a little space and spread out Yang Hui’s drawings, placing the smaller sheets atop the others.

“This is pretty simple. Are you sure you want the combustion chamber made like this?” His question revealed his expertise—he immediately recognized that the combustion chamber Yang Hui and Wu Dabo brought was quite different from the standard design.

Since they’d been found out, Section Chief Wu simply gave a brief introduction. “Let’s talk about the flame tube first. Since the operating environment isn’t too harsh, we’re using GH39 alloy. Maximum diameter 168, length 150. The tube is in two sections with six fuel inlets. The heat capacity of the flame tube is 1200–6500 KJ/(m^3·h·Pa), with three cooling air films at the head, middle, and tail, using a corrugated ring pressure inlet method. These are straightforward to manufacture; for details, see the second flame tube drawing.” As he spoke about his design, Wu was unstoppable, clearly eager to explain more.

The workshop foreman, adept at listening and reading blueprints, interrupted when Wu finished. “The shell of this combustion chamber will need machining; you’ll have to go to the next shop.” He jotted down a few figures on a blank sheet of paper, then returned the bound drawings to Section Chief Wu. “I’ve got what I need in my head now. No need for the blueprints—just head next door to the machine shop for the shell.”

This left Yang Hui quite impressed. It was rare to meet such a seasoned foreman who could memorize the essential data at a glance, something few workers could do.

Since they no longer needed the blueprints here, Yang Hui called for Section Chief Wu to join him in seeking out Old Wang next door. As it happened, the machine workshop was indeed run by an engineer named Wang. Before they even entered, they heard someone say, “Engineer Wang, this one’s done!”

Engineer Wang inspected the freshly machined part with a smile. It was flawless—fully up to standard. He set aside his measuring tools and turned to leave.

“Engineer Wang, our part is…” The ritual introduction followed: stating their purpose and presenting the blueprints.

Putting on his glasses, Engineer Wang studied the inner and outer shells of the combustion chamber, commenting on key details as he went. “30CrMnSiA structural steel, the front mounting edge of the outer shell connects to the rear of the engine casing, the inner shell has two bearing supports, the diffuser case and conical support plate are joined, and the rear end mates with the guide vane case…” He muttered to himself for quite a while, thoroughly digesting the drawings. Then he called over a young apprentice, gave him instructions, and handed him the blueprint.

“All right, this part is pretty simple—probably the easiest job in the whole shop right now. This lad can handle it. Just wait a bit and it’ll be done. I’m off to take care of something else.” Seeing the engineer entrust the job to a clearly inexperienced newcomer left Yang Hui at a bit of a loss.

“Is your design really that simple?” Helpless, Yang Hui had to ask Section Chief Wu, wanting to know just how minimal the requirements were for this combustion chamber.

Section Chief Wu was also puzzled. “I designed it based on your framework. When we calculated the specs, we used the required thrust as the basis, so the combustion chamber can be made rather roughly. That’s your doing.” His innocent expression seemed to say, “It’s your excellent design with such generous tolerances—don’t blame me.”

Yang Hui was left speechless. He hadn’t expected his design to be so robust. It truly was the first engine component he’d ever designed—he’d never done this in his previous life, having at most listened to flight test bragging.

“This really is a surprise. I didn’t expect it either.” He was the very image of someone taking advantage while playing it humble—someone who deserved a good-natured scolding.

Regardless of Yang Hui’s astonishment or satisfaction with his own work, time passed, and soon the combustion chamber shell was finished. The engineer Wang called them over to inspect the first part. Once it was confirmed to be correct, the apprentice set about making the other two shells. They needed three combustion chambers to complete all the test items. For a model jet engine, these components were consumables anyway—even in later years, they rarely lasted more than twenty or thirty hours before being scrapped. These were, after all, for model aircraft; cheap goods never last long.

Looking at this pile of parts, Yang Hui couldn’t help but feel delighted. This was, in the truest sense, the first major component of the model aircraft project to come off the drawing board—the future suddenly seemed hopeful.

With that thought, he hurried next door to check if the flame tubes were finished. Once they were ready, he could assemble them and see the combustion chamber take shape.

Sure enough, the sheet metal workshop was efficient—they’d already completed two flame tubes. After a brief exchange, Yang Hui took one and, walking along, marveled at the craftsmanship.

In the machining industry, every specialty leaves its own distinctive marks. For a flame tube made by hand from sheet metal, you’d expect at least some faint hammer traces, even if a mallet was used. But on this flame tube, Yang Hui couldn’t detect any evidence of hammering. It was a masterpiece—he couldn’t help but admire the foreman’s exceptional skill.

Lost in admiration, he arrived at the machine shop, where workers were already assembling some parts in the yard. However, since the flame tube was still missing, assembly wasn’t complete.

Yang Hui handed the flame tube to the worker, who checked it against the assembly drawing and began the careful process of fitting it together. Thanks to its generous tolerances and thoughtful design, assembly was straightforward. In just a few minutes, the combustion chamber was fully assembled.

Comparing the finished piece with the rendering on the drawing rack, everything seemed in order—at least at first glance. Of course, only subsequent tests would reveal any hidden design flaws.

“According to your blueprint, you’re using gasoline as fuel. Why don’t we give it a try? We have a blower and gasoline—enough to try igniting the combustion chamber.”

The worker who’d just finished assembling it was clearly eager to try it out. Yang Hui was tempted too—his curiosity piqued—but reality intervened. This combustion chamber required preheating with gas before ignition, a somewhat troublesome process, and there was no propane available here. So he had to disappoint the enthusiastic worker.

“We can’t. The design calls for propane preheat and ignition. Starting with liquid fuel won’t work,” Yang Hui explained regretfully.

Damn, this engine really is a pain, the worker must have thought. That was probably the only way to sum up his feelings.