210: Chapter 210: Test started at 7:00 AM; shock absorption data is out.

6:58 AM. Cockpit.

The two bowls of gruel sent by Song Ya were empty, the empty bowls left on the left side of the console.

Lu Chen sat in the pilot's seat, his hand resting on the engine start control panel.

Lin Wan's voice came through the communicator, echoing.

"City Lord, I'm next to the seventh set of Hydroponic Racks in the Greenhouse. The stopwatch is ready. Once you start, call out the speed, and I'll record the bump amplitude."

"Okay."

"Old Du is here too. He brought a vibration frequency measuring rod to measure the engine's vibration frequency in real-time."

"Okay."

Lu Chen flipped open the protective cover of the engine start control panel.

The main engine had been idling for a long time and was ready to move.

He pushed the main engine power up from eight percent idle.

The entire Polaris emitted a low-frequency hum. The vibration traveled from the chassis to the ground, then crawled up the walls.

"Lin Wan, engine started. Currently at fifteen percent power."

"Recorded. The seventh set of Hydroponic Racks is shaking, amplitude within two millimeters, no signs of root dislocation." Lin Wan spoke quickly. "Old Du measured it; the engine vibration frequency is currently 4.2 times per second. It's outside the spring's natural frequency of ten times, so there's no resonance."

Lu Chen continued to push the lever.

"Thirty percent."

The tracks engaged, and the Polaris pressed forward as a whole, speed climbing from zero.

"Five kilometers per hour."

"Lin Wan, five kilometers."

"Seventh set of Hydroponic Racks, amplitude three to four millimeters, roots swaying, no dislocation." Lin Wan took a breath. "Engine vibration frequency is 6.8 times per second, still within the safe range."

"Ten kilometers per hour."

The vehicle's vibration developed a rhythm. Low-frequency vibrations leaked from the engine room, surging up along the steel frame.

"Lin Wan, ten kilometers."

"Amplitude five to seven millimeters, root swaying intensified." Faint noises came from Lin Wan's end. "One rootlet at position three has poked its head out of the nutrient solution, but hasn't fully dislocated; the solution is still wetting the root. Old Du says the engine vibration frequency is 9.1 times per second, approaching the lower edge of the resonance range."

Lu Chen kept the speed at ten kilometers and didn't push it higher.

"9.1 times. How far from the lower edge of resonance?"

"Old Du says the spring's natural frequency is ten times per second. Now it's 9.1, so there's a margin of 0.9 times before the resonance range. Pushing it further would be dangerous."

"What would the engine vibration frequency be at forty kilometers?"

"Old Du doesn't have high-speed data. He says based on a linear estimation, forty kilometers would be thirteen to fifteen times per second, which would pass through the resonance range."

Lu Chen pulled back the engine power. The Polaris slowed down and came to a steady stop again.

He leaned back against the seat, watching the speed indicator on the panel return to zero.

"Ten kilometers, 9.1 vibration frequency, nearing the lower resonance edge."

"Forty kilometers, thirteen to fifteen times, passing through the resonance range."

"The effect of the damping layer within the resonance range will inversely amplify the bumps."

"This is more troublesome than estimated."

"Lin Wan."

"Here. I've finished checking all the roots. Swaying, no dislocation, data is stable."

"Is the damping effective within ten kilometers?"

"Yes, the bump amplitude is reduced by twenty-five to thirty percent compared to before having the damping layer. Old Du says the springs are working normally in the non-resonance range."

"The problem is that it will enter the resonance range above forty kilometers."

"Right." Lin Wan paused for a second. "Old Du says if we want to push the resonance frequency up to eighteen to twenty times, we need to increase the number of spring coils, changing it from the current six to eight coils to ten."

She took a breath and spoke faster.

"Wait, increasing two coils makes the spring softer, and the natural frequency decreases. No, that makes resonance more likely."

"So we should reduce the number of coils to make the springs stiffer and push the natural frequency higher."

"Old Du says reducing it to four coils can push the natural frequency to eighteen to twenty times per second. That way, at forty kilometers, the engine vibration frequency of thirteen to fifteen times won't be in the resonance range."

"If the spring coils are reduced from six to eight to four, the stiffness increases. Will the attenuation amplitude decrease?"

"It will decrease slightly. Old Du estimates it will drop from thirty percent to twenty-two to twenty-five percent." Lin Wan replied. "But at least it won't inversely amplify at high speeds."

"Change it." Lu Chen finalized the matter. "Replace all the springs with four-coil ones today. How much steel rod is left?"

"About five meters. Old Du says with four coils, each spring uses sixty centimeters of steel rod, so five meters can make eight." Lin Wan did the math. "If we really replace them all, sixteen hundred springs would need nine hundred and sixty meters of steel rod. We don't have enough material."

The Cockpit went silent.

"Use an incomplete plan." Lu Chen wrote a few lines in his notebook. "Prioritize replacing the springs for the Hydroponic Racks in the main load-bearing areas. Keep the original six to eight coils for the ones at the edges. Replace the sixty sets in the central area first."

He paused.

"These sixty sets will have effective damping at high speeds. The forty sets at the edges will accept minor resonance; the losses are controllable."

"Sixty sets, four coils, requires nine hundred and sixty meters of steel rod. How much is left of that batch of steel rods from The City-State?"

"Five bundles were brought in, each two hundred to two hundred and fifty meters. Subtracting what's been used, there are nine hundred and fifty to one thousand meters left."

"Enough."

"Okay." Lin Wan let out a breath over the communicator. "I'll have Old Du start the replacement today. It should be finished by 2:00 PM. We'll do another high-speed test tomorrow."

"Good, push the speed to forty kilometers and see the actual effect." Lu Chen put down his pen. "The meeting is in two hours. Get to work, I'm going to call the others."

"Understood."

The communicator hung up.

Lu Chen looked at the panel.

The fifth pale red record in the signal log was stuck there, timestamp 05:49:07.

8:00 AM sharp. Cockpit.

Zhou Yuan, Zhao Tiezhu, and Lin Xiao entered one after another.

Zhou Yuan's eyes were bloodshot from staying up late, but his expression remained steady.

Zhao Tiezhu looked at the panel first upon entering. Seeing the color of the fifth signal had changed, he didn't say a word and found a seat.

Lin Xiao paused at the door, looked up at the bottom right corner of the panel, his eyelid twitching. He walked in and took a chair near the edge.

Lu Chen looked at the three of them.

"The fifth signal, 5:49 AM today, 2.8 seconds, seven degrees west of due north." Lu Chen began. "The main force of the Iron Hoof Legion has entered the departure window. At the earliest, they will reach the Rustwind Wasteland on the seventy-first day, which is eight days from now."

No one in the Cockpit responded; only the sound of breathing could be heard.

"The confirmed time we have left is eight days." Lu Chen flipped his notebook to today's page. "There are three things to do in these eight days."

He paused for a beat, letting the three of them digest the words.

"First, from today onwards, the relocation speed must be no less than eight hundred people per batch. Do as many as possible. There are 9,085 registered residents today. Within eight days, I want to push this number to over 16,000."

Lin Xiao nodded but didn't speak.

"Second, the adjustment of the damping layer will be completed today, and a second test will be conducted at 7:00 AM tomorrow. If the results meet the standard, the Polaris will enter a state where it can travel at full speed immediately."

Zhao Tiezhu put his hands on his knees and rubbed the seams of his pants.

"Third." Lu Chen closed the notebook and looked at the three. "The degradation window for The City-State's remains—we need to make a final judgment. The Auxiliary Engines are expected to run out on the seventy-third or seventy-fourth day, and the Iron Hoof Legion will arrive as early as the seventy-first day. Is there a window, and where is the limit? I need an answer today."

Zhou Yuan looked up.

"City Lord, I recalculated yesterday. If the Iron Hoof Legion establishes a Forward Base after arriving at the Rustwind Wasteland on the seventy-first day, that process will take two to four days." Zhou Yuan reported the data, his throat dry. "We can utilize this two-to-four-day Base-building Window and degrade The City-State's Auxiliary Engines as soon as they run out on the seventy-third day."

"The Base-building Window is two to four days. How long does the degradation take?"

"Based on the previous degradation experience of the two Lv.3 wrecks and the Ice Thorn Lv.4 wreck, The City-State's remains are larger in scale and will take five to eight hours." Zhou Yuan paused. "Two to four days for base-building, five to eight hours for degradation. Time is sufficient, but there is one prerequisite."

"Speak."

"During the Iron Hoof Legion's base-building period, they cannot actively harass our position. If they send scout vehicles while building the base, the Polaris will be stuck in place during degradation. A sitting duck."

The Cockpit was so quiet that only the sound of the wind from the vents could be heard.

Lin Xiao crossed his hands on his knees and looked up at Lu Chen.

"Lu Chen, how many Truth Points can you get from degrading the remains over at The City-State?"

"Estimated to be over thirty thousand."

Lin Xiao swallowed hard.

"Is it worth the risk?"

Lu Chen weighed this question in his mind for three seconds.

"Thirty thousand points."

"Based on the second batch of Lv.3 nodes ranging from seven thousand to fifteen thousand points each, thirty thousand points can unlock three to five nodes."

"Radiation-proof Lead-lined Inner Shell, Gas Turbine Generator Set, 155mm electromagnetic acceleration railgun."

"155mm electromagnetic acceleration railgun."

These words rolled around on the tip of his tongue.

"It's worth it." Lu Chen spoke. "But I need the cooperation of the Dawn Legion. During those five to eight hours of degradation, can Forge provide us with real-time intelligence on the positions of the Iron Hoof Legion's scout vehicles?"

He looked at Zhou Yuan.

"Let me know how far their people are from us."

Zhou Yuan put his hand on the communicator.

"I'll ask Forge today."

"Good." Lu Chen stood up. "Today's meeting ends here. Everyone, get to work. I want the first progress report at 4:00 PM."

The three of them stood up and walked out.

Lin Xiao was the last to leave. He paused at the door and turned to look at Lu Chen.

"Those thirty-thousand-plus people," Lin Xiao said, his voice tight, "are still waiting in The City-State."

"Understood." Lu Chen replied. "Go and accelerate the relocation."

Lin Xiao said no more, turned, and walked out.

The Cockpit door closed.

Lu Chen sat back in the pilot's seat and looked at the panel.

"Signal log."

"The fifth pale red record, 05:49:07."

"Eight days."

He picked up a pen and wrote a line at the bottom of today's list.

"degradation window assessment, contact the Dawn Legion, wait for Forge's reply."

He closed the notebook and waited for the 4:00 PM news.