Chapter Forty-Seven: Ignition in the Combustion Chamber

Having spent the entire morning bringing the designs on the blueprints to life, by the time I walked out of the factory, there were already three combustion chambers in the sidecar of the motorcycle. I twisted the throttle all the way, yet the speed simply wouldn’t pick up; the blueprints in the sidecar didn’t even stir. How fast could it possibly go? I couldn’t help but sigh inwardly: this old motorcycle’s technology was indeed a bit dated. After all, it was World War II German engineering. Though it carried BMW’s heritage, it had by now become thoroughly localized in the Republic.

Still, I managed to return to the institute. From a distance I could see the two remaining colleagues from our department standing by the gate. Before the bike had even come to a stop, Tian Zhuang had already grabbed the combustion chamber samples from the sidecar and was examining them.

“You’re quick on your feet. Here, take these as well,” I said, handing him the rest before going to return the keys.

Section Chief Wu picked up the blueprints and led the way. This time, instead of heading toward the office area, we turned onto a side path leading to the institute’s engine testing center. There, the equipment was more than adequate—testing a miniature turbojet combustion chamber was almost trivial.

From quite a distance, the shrill roar of a turbojet engine reached our ears—far more imposing than anything our still-in-development miniature engine could muster. Amidst the piercing wail, the three of us finally arrived at the southeastern corner of the testing center.

There weren’t many engines running here, only all sorts of testing instruments and a tangle of wires in various colors, connecting sensors at one end to analytical devices at the other.

Given the institute’s current state, with so few projects underway, most of the equipment in the component testing area stood idle. Those few machines still running had drawn crowds of idle staff, clustered thickly around them.

Nevertheless, someone soon noticed the three of us, our combustion chambers in hand. After a moment’s careful scrutiny, he recalled that there was indeed a recent project—though the name hadn’t sounded promising, any work was better than none.

“Everyone, come here! There’s a new project!” he called from atop a platform. Instantly, the onlookers flocked over in a wave, all eager to inspect the combustion chambers—hardly interested in the three of us.

“So small? What could this possibly be used for?”

“Not even a missile, I’d wager.”

“Missiles use solid fuel—that’s obviously not what this is.”

“Then what is it...?”

A babble of voices debated back and forth, but no matter how hard they tried, no one could figure out what kind of engine this belonged to. Only a few in the design center had heard about the model aircraft project, and even now, no one was willing to mention the miniature turbojet—it simply had too little presence.

Eventually, someone remembered that the institute had approved a self-funded model aircraft project, and this must be it.

“A combustion chamber for a model aircraft engine, right? The institute’s footing the bill.”

At last, these technically-minded testers, indifferent to outside affairs, understood. It all made sense now—no wonder it was so basic and small.

“That’s right, it’s a combustion chamber for a model aircraft. We kept the design simple, just enough to function,” Section Chief Wu explained, having intended to say little, but seeing so much speculation, he decided to elaborate.

“The test pieces are ready. Now it’s up to you to run the tests. If the combustion chambers pass, we’ll be ready for final installation trials.”

In the end, all discussion came back to the main point: testing the combustion chambers.

“This one doesn’t have high requirements—we’ve omitted some of the less critical tests. There are three chambers here; each is designed for a service life of about twenty-five hours. That should be enough for our purposes,” he said, pulling out a test sheet and preparing to hand it to the supervisor.

The supervisor glanced over the test plan and immediately began to organize things, cutting off the chatter to assign tasks.

“We’ll use one of these for mechanical testing—take it apart and run the necessary checks,” he said, examining one chamber before passing it to the team responsible for mechanical analysis.

The recipient, pleased to finally have work to do, gathered his team and left with the sample.

As the crowd thinned, the supervisor continued, “The other two will be used for combustion performance tests.” He handed the remaining chambers to two group leaders, and the rest dispersed to their tasks.

Noticing the signature on the test sheet, the supervisor was a bit surprised.

“Come on, I should call you Section Chief Wu now, right? Let’s fill out the test forms first,” he said.

Wu had been at the institute for over a decade, always working with combustion chambers. He’d been to the testing center countless times and was well acquainted with the supervisor.

Just as they were heading inside, Yang Hui finally arrived at the component testing area.

“Hey, Chief Wu, you’ve already started the tests?” Not seeing the combustion chambers around, Yang Hui realized the process had already begun.

“Not yet, we just handed out the samples. I’m about to fill out the test forms—come along and have a look,” Wu replied, inviting Yang Hui to join.

“Oh, and let me introduce you: this is Chief Li, responsible for component testing here. We’ve been friends for years—he’s easy to work with.” Wu made the introductions, then continued, “And this young man is Yang Hui, who joined us this year—he’s the overall lead for the model aircraft power system.”

“Pleased to meet you,” the two exchanged greetings before the three of them walked to the office. Tian Zhuang and his companion had already hurried off to observe the tests.

Inside, they completed the test forms and Wu signed them. Then Li suggested they head to the test site, needing to distribute the forms—without them, no testing could proceed.

By now, a group of lab-coated staff had already installed the combustion chamber onto the test rig, securing it in place. Sensors were attached both on the outside and inside the combustion tube walls.

Seeing that the temperature testing team had finished preparations, Li handed over the relevant test form to the local supervisor before hurrying off to distribute the others.

An important test was about to begin. Naturally, Yang Hui and Wu weren’t going anywhere—they had to see this in person.

“Alright, the test form is here. We can begin,” the supervisor announced.

Yang Hui and Wu quickly withdrew beyond the safety barrier—combustion chamber tests were not without risk, best to keep their distance.

“All personnel, please note: combustion chamber temperature test about to commence. Unrelated staff, please move to the safety zone.”

After confirming readiness with hand signals from every section, the supervisor continued.

“Fan system preparing to start, introducing air.”

“Fan system operational, air pressure increasing.”

The large fan began forcing air into the combustion chamber.

“Prepare propane.”

“Propane ready. Injection authorized.”

“Commence propane injection.”

On the old monitor, the ratio of propane to air shifted steadily toward the optimal combustion mix. Once the data reached target levels, the supervisor pressed the ignition button.

With a faint pop, ignition succeeded on the first attempt—a reliable start, so far everything was going smoothly.

All eyes were glued to the monitor, watching the constantly updated data—the temperature sensors feeding back readings from the chamber and tube walls.

Once temperatures rose above gasoline’s flash point, reaching 446 degrees, the order was given.

“Inject gasoline, stand by to cut propane.”

A series of sputtering pops followed—clear evidence that gasoline combustion was unstable at first. Eventually, the transition to fuel combustion succeeded, though occasional flameouts at some inlets still occurred, until reignited by flames from neighboring jets.

Seeing this, several of the team furrowed their brows—it was clear there was a combustion problem, most likely related to the fuel.

“It’s probably a fuel issue,” Yang Hui observed, pinpointing the key cause of the combustion instability.