Four days after Lin Yuan said those words, the Thunderclap Project was progressing twelve hours faster than he had expected.
March 31, C.E. 71. Underground firing range, Western District Weapons Test Site, 811 Institute.
Fang Heping mounted a barrel assembly nearly two meters long onto a fixed support. An ammunition belt snaked upward from the feed box at the side, each link holding a dark gray round the size of an adult's fist.
Spiral grooves gleamed with an oily metallic sheen beneath the firing range's cold lights.
"This is for a Mobile Suit?" Han Zheng stood outside the safety line, craning his head forward half an inch.
"Obviously." Fang Heping patted the recoil buffer ring at the rear of the barrel, his voice hoarse from seven straight days of rushing work. "Seventy-five-millimeter caliber, belt-fed, forty rounds. Every one of them is a Rocket-Assisted Delayed Implosion Round. Muzzle velocity is eight hundred meters per second, with the rocket stage accelerating it to fourteen hundred."
Han Zheng whistled.
"What are you whistling for?" Fang Heping shoved his wrench back into his tool bag and crouched to inspect the feed box's locking mechanism. "Do you know how much recoil this thing has? Its peak impulse per shot is six times that of the United Army's standard Short Sword autocannon. Six times."
"Black Iron can take it."
"Whether Black Iron can take it is Xu Yanqiu's problem. What I'm telling you now is whether you can take it."
Fang Heping stood up and rubbed the dust from his hands onto his work pants.
"After more than three consecutive shots, the torque feedback from the unit's right-arm servo motor will transmit directly into the control stick. Your wrist will feel like someone is hammering it. Over and over."
Han Zheng pulled his head back and flexed his right wrist.
"Team Leader Fang, I've fired a seventy-six-millimeter autocannon on a Short Sword."
"The recoil of a seventy-six-millimeter autocannon is nothing compared to this." Fang Heping returned to the control console, his finger resting beside the firing button. "Don't compare credentials with me. We're firing at targets first today. You watch from behind the safety line."
At the far end of the range, a retired Short Sword cockpit module had been welded onto a test rig, its exterior covered by a standard-thickness titanium alloy armor plate.
Lin Yuan stood behind the observation window in the control room. Sheng Lan was on his right, and the high-speed camera on the terminal screen had entered standby mode.
"Fang Heping, are you ready?" Lin Yuan pressed the comm button.
"Ready. Single-shot mode, first round."
"Fire."
What erupted from the muzzle was not flame.
It was a concentrated orange-red exhaust plume that flared to life eighteen meters after the round left the barrel, like a low-flying meteor trailing fire as it smashed toward the target stand.
The entire firing range shook.
Sheng Lan felt the tremor through the soles of her feet, while a cup on the control room glass shuddered and left a streak of water.
The high-speed replay appeared three seconds later.
The round struck the armor plate, penetrating thirty-one millimeters. The rocket-assisted stage continued advancing another seven millimeters inside the armor before the delayed fuse triggered and the implosion chamber detonated.
The armor plate had not been penetrated.
But the inner wall of the cockpit module behind the target stand had shattered.
Sensor readings streamed densely across the console: the stress peak produced by the shockwave on the armor's inner surface vastly exceeded the cockpit structure's load limit; the seat's mounting bolts had snapped; the instrument panel had blown apart; and the gel dummy simulating a human torso had completely deformed below the neck.
Fang Heping's voice came from the other end of the range, unnaturally flat.
"Director, the warhead didn't penetrate the armor."
"I saw."
"But the cockpit module is scrap."
"I saw that too."
The firing range fell silent for two seconds.
Han Zheng's voice squeezed in from behind the safety line.
"Team Leader Fang, if this thing hits someone, what happens to the pilot inside?"
Fang Heping did not answer him.
Lin Yuan pressed the comm button.
"Burst-fire mode. Three-round burst. Second target."
The second target stand held a Phase-Shift Armor simulation panel reconstructed from the Spark Data. Its thickness and materials precisely replicated GAT-X series standards, with a battery pack beneath it maintaining the energy supply.
Fang Heping adjusted the barrel's aim, his finger hovering over the firing button.
"A three-round burst will stack the recoil peaks. I doubled the anchor bolts on the fixed support. It should hold."
"Fire."
Three muffled booms erupted in rapid succession, less than 0.4 seconds apart.
The first round struck the PS Armor's surface. The energy layer flickered once, and the round ricocheted away, leaving only a shallow crater.
The second landed two centimeters off, hitting the edge of the same area. Visible ripples appeared in the Phase Shift Armor's energy feedback.
The third hit the overlap between the first two shots dead center.
At that instant, the PS Armor's energy layer flashed from a localized overload. The round embedded itself in the surface during that fraction-of-a-second gap, its rocket stage igniting and driving it twelve millimeters in.
Then it exploded.
The armor plate did not crack apart, and the PS energy layer quickly recovered, but a stress fracture radiated outward from the center of the plate.
The battery's charge reading dropped by fourteen percent.
Fang Heping stared at the data for a long time.
"A three-round burst can drain fourteen percent of the PS Armor's charge. If we maintain continuous output..."
"No need to calculate it." Lin Yuan's voice carried down from the control room. "PS Armor has limited stored energy. As long as we maintain fire coverage, it will shut down on its own. Once it does, it's just ordinary alloy."
"And then the fourth round turns the person inside into paste." Fang Heping locked the firing button and slowly let out a breath.
Han Zheng did not whistle again.
In the control room, Sheng Lan sent the high-speed footage's frame analysis data to Lin Yuan's terminal.
"Director, the barrel temperature rises rapidly in burst-fire mode. After three rounds, the bore wall temperature is already close to the material warning threshold. If it is to sustain output in actual combat, it needs a cooling solution."
"Fang Heping will handle it. What else?"
Sheng Lan turned another page of the record.
"With belt feeding, the interval between the second and third shots was 0.7 seconds slower than the design value. The feed box's belt-link transmission mechanism underwent slight displacement in the high-recoil environment."
Lin Yuan's gaze paused on the data.
"0.7 seconds."
"0.7 seconds. On the battlefield, that's enough time for a ZAFT Ginn to make an evasive turn."
Lin Yuan closed the terminal.
"Inform Fang Heping. Redesign the ammunition belt transmission mechanism. Tighten the tolerance to within 0.1 millimeters. Before that, mount the Bombard Gun on Black Iron for a static weapon-handling test."
Sheng Lan made a note in her memorandum.
"What about Han Zheng's condition?"
"He keeps asking when he can get in the cockpit."
"Tell him tomorrow."
Sheng Lan's pen tip paused.
"Director, Black Iron's right-arm joint actuator hasn't been replaced with the reinforced version yet. Xu Yanqiu's report this morning said the fit clearance between the Ceramic Steel external armor plates and the joint bearings is too large, causing uneven load distribution."
Lin Yuan walked toward the control room exit, his hand resting on the doorknob.
"That's why we need to test it. If we never put it in the cockpit, we'll never know where it will crack."
The next morning.
811 Institute Comprehensive Test Grounds.
Han Zheng sat inside the cockpit of the Black Iron Prototype, his right-hand control stick linked to a Bombard Gun thicker than his entire arm.
The unit stood on a fixed support. Its power was not activated; it was purely a static posture test.
He pulled the trigger.
One shot.
The barrel roared, and the recoil traveled back through the unit's right arm into its torso. The control stick in the cockpit jolted violently, numbing Han Zheng's wrist.
Two shots.
Three shots.
As the third round fired, the stress curve at the right elbow joint suddenly shot upward on the monitoring screen, and a metallic shriek entered the cockpit from the unit's outer shell.
"Cease fire!" Sheng Lan's voice exploded over the comm channel.
Han Zheng released the trigger.
Xu Yanqiu had already rushed to the edge of the test grounds, still wearing the goggles around his neck.
"Who approved firing a three-round burst before the right arm was replaced?"
His voice could penetrate the soundproof wall.
"Which idiot designed this joint transmission system? The stress distribution of the bearing housing didn't account for lateral impact loads at all! Was this designed for serving tea or for war?"
The two engineers from the structural team shrank into a corner, and neither dared answer.
Lin Yuan stood beside the control console, the crack propagation diagram for the right arm still flashing on the screen.
He was not looking at the cracks.
He was looking at another set of data.
Ammunition belt feed timing.
The interval between the first and second shots was normal.
Between the second and third shots, the feed had been delayed by 0.7 seconds.
Exactly the same as yesterday.
He pressed the comm button.
"Fang Heping."
Fang Heping's panting came through the comm channel. He was recovering shell casings over at the firing range.
"Here."
"The issue with the ammunition belt transmission isn't tolerance."
Fang Heping stopped panting.
"What do you mean?"
"Both yesterday's target test and today's weapon-handling test had a 0.7-second delay in belt feeding. The error was completely identical. If it were a random fault caused by physical displacement in the transmission mechanism, the two sets of data shouldn't match so precisely."
Silence fell on Fang Heping's end.
"Check the feed box's electromagnetic release valve." Lin Yuan rested his finger beside the 0.7 figure on the screen. "The valve's response curve may be developing a fixed delay at high temperatures."
The comm channel disconnected.
Xu Yanqiu was still cursing in the test grounds. His voice gradually shifted from fury to the commanding roar of someone coordinating work, and he began directing the structural team to remove the right-arm joint for inspection.
Sheng Lan walked over to Lin Yuan, her memorandum already turned to a fresh page.
"Director, there's an update from the Pacific Fleet."
Lin Yuan turned his head.
"The Atlantic Federation's Third Detachment crossed the median line four hours ago. It is now less than eighty nautical miles from East Asia's warning line. The vanguard consists of two Drake-class ships carrying an unknown number of Short Sword Mobile Suits."
Lin Yuan lifted his gaze from Black Iron's damage data and looked at the thin situation report in Sheng Lan's hand.
"Speed?"
"Standard cruising speed. No acceleration."
"Formation?"
"A dispersed search formation. It doesn't look like a decisive battle. It looks more like they're searching for something."
Lin Yuan shut off the control console screen.
"They're not looking for something. They're measuring East Asia's response time."
Outside the test grounds, Xu Yanqiu's cursing still echoed.
Lin Yuan removed his communications headset and set it on the console.
"Sheng Lan, notify He Changying. Black Iron's right-arm joint must be replaced within forty-eight hours. Replace the ammunition belt feed valve at the same time."
Sheng Lan's pen stopped.
"Director, even after forty-eight hours, Black Iron's condition may not be fully intact."
"I know."
"What if they cross the line within those forty-eight hours?"
Lin Yuan picked up his headset and walked toward the test grounds.
"Then we fight with a half-finished product."
Before you continue