Rebirth: Starting from Lighting Up the Tech Tree

Chapter 186 Star Arrow Combination 1

After the fifth recovery of Cangqiong-1, Li Guodong placed the data report on the conference room table, pointed to the wear record of the recovery capsule, and said that according to the decay rate, the lifespan of the first-stage thruster is about eighteen times, and whether it can reach the twentieth time is questionable.

Zuo Cheng asked, "Why?"

Li Guodong explained that the engine nozzle experiences thermal stress concentration during atmospheric reentry, generating microcracks with each recovery attempt, which accumulate to become a potential hazard. Two solutions exist: first, replace the material with single-crystal rhenium alloy instead of the existing nickel-based high-temperature alloy, tripling the cost; second, change the recovery method to a complete system, integrating the spacecraft and rocket for unified landing and reuse.

Zuo Cheng mentally went through the words "whole-body recycling".

This is precisely the core direction of Sky Dome II.

The next day, the research institute held a project approval meeting for the Cangqiong-2 rocket. More than twenty people sat in the meeting room, including technical leaders from various fields such as rocket structure, attitude control, engine, and materials. Zuo Cheng drew a diagram on the whiteboard, labeled "Star-Rocket Integration" next to it.

He said that Cangqiong-1 solved the problem of first-stage recovery, while Cangqiong-2 will solve the problem of overall recovery, ensuring that the rocket remains intact from launch to landing, without disintegration or separation, and can be reused upon return.

Bai Qing, the chief engineer in charge of rocket structure, raised his hand. "Integrated recovery means that the second stage also needs to bring back the return system. Is the payload ratio too low?"

Zuo Cheng said that the target for near-Earth orbit transport capacity is ten tons, with an effective payload ratio of no less than 3.5, which is an indicator that cannot be compromised.

Du Wen, the attitude control chief, said that the difficulty of the overall landing lies in the terminal guidance phase. Cangqiong-1 was a single-stage independent recovery, with a relatively fixed mass. During overall recovery, the amount of residual fuel is unpredictable, the center of gravity continuously changes, and the control algorithm for the final five kilometers needs to be completely rewritten.

Zuo Cheng said that the research institute would handle the algorithm work, while he would assist with the system-level optimization. He didn't specify what he meant by "system," but he knew that the "vertical recovery precision control" blade for the commercial aerospace branch had been unlocked, and with the support of a 1.3 technology boost, the algorithm development speed would be much faster.

Bai Qing's team solved the payload ratio problem in three weeks, merging the two separate engine nacelles into a foldable support structure, adding four small landing outriggers to the second stage that are stored in the side wall of the rocket body and automatically deploy before landing, reducing the structure's weight by nearly 200 kilograms. The payload ratio was ultimately achieved at 3.7, exceeding the target set by Zuo Cheng.

The materials team simultaneously came up with a new solution: adding a film cooling coating to the inner wall of the nozzle. This was much cheaper than replacing the material and could reduce the thermal stress concentration problem by half again. With the two solutions combined, Li Guodong re-estimated the lifespan, saying that thirty cycles was a conservative estimate, and with proper implementation, it could potentially reach forty cycles.

Zuo Cheng directly participated in the derivation of the terminal guidance algorithm. He worked for two consecutive nights in the small conference room of the research institute, his whiteboard covered with formulas. Yu Ying delivered takeout, put down the box, pulled up a chair next to him, opened her own files, and stayed up with him.

She didn't urge him or say anything, only occasionally refilling his water glass. At two in the morning, Zuo Cheng finished drawing the last derivation box on the whiteboard, stopped, and said, "It's working."

Yu Ying looked up and said, "Then go to sleep."

The core of the algorithm is adaptive centroid estimation, which calculates the centroid offset in real time by fusing three signals: fuel consumption rate, inertial measurement unit data, and barometric altimeter data, and updates the control command every 20 milliseconds. The accuracy is two orders of magnitude higher than that of Cangqiong-1.

Three months later, the overall recovery test was carried out at the Northwest Launch Site.

Standing at a height of thirty-eight meters, the Sky-Dwelling No. 2 rocket appeared exceptionally long on the Gobi Desert. The morning wind blew in from the Gobi, carrying sand and dust. The countdown began over the loudspeaker, the engine ignited, and orange flames erupted from the thrusters. The rocket slowly rose, accelerating faster and faster, its exhaust trailing a white beam of light.

Three minutes later, Sky2 broke through the clouds and disappeared into the blue sky. Five minutes later, the payload module separated and entered its designated orbit.

The next step is the recycling phase.

The engine ignited a second time, and the Cangqiong-2 rocket began its return journey. The terminal guidance algorithm was activated, data on the screen was updated in real time, the center of gravity offset changed continuously, control commands were updated every twenty milliseconds, and the rocket's attitude remained precisely pointed towards the landing point.

One kilometer, five hundred meters, two hundred meters.

The landing engine ignited, and the rocket rapidly decelerated in the last hundred meters. Zuo Cheng held his breath.

Landing, touching down.

The rocket stood firmly on the landing platform without any tilting. The numbers on the screen showed a landing deviation of 0.3 meters.

Li Guodong said in a low voice, "It's much better than the 1.2 meters of Cangqiong-1." Applause rang out on the observation platform.

The test results that afternoon surprised everyone: the wear of the engine nozzles was 41% lower than that of the Sky One after the same number of launches. At this wear rate, the Sky Two's design life can reach thirty launches, and the cost per launch will be reduced by one-third.

After submitting the test report, Yu Ying stared at the numbers and said, "The cost of each launch of Cangqiong-1 is 30 million, while Cangqiong-2 can be done for 20 million."

Zuo Cheng said, "Even lower. The next step is a rapid system inspection, with the goal of completing all tests and launch preparations within six hours of landing."

Yu Ying looked up. Six hours?

Zuo Cheng said that the detection system is fully automated. Sensors report in real time the engine endoscope, cable path, and structural stress. Technicians only need to confirm the abnormalities and do not need to check from the beginning.

Yu Ying said, "In that case, theoretically, the same rocket could be launched twice a day?"

Zuo Cheng said, "Yes, this is key to launch density. There are also multiple launch sites operating in parallel and the launch team being expanded; Cangqiong-2 is a core variable in this regard."

She was silent for a while, then looked at the night sky in the northwest and said, "Sometimes I wonder how you managed to figure all of this out."

Zuo Cheng said that he often doesn't understand things clearly, but he seems to understand things clearly because he doesn't talk about them.

Yu Ying chuckled softly and said, "Liar."

The news of the successful overall recovery test appeared online the following day, with tech media headlines such as "Star-Rocket Integration Technology Successfully Verified, Launch Costs of 402 Reduced by Another 30%." Several European media outlets quoted the news, adding that, to date, this technology has no precedent globally.

Zuo Cheng saw these reports in his office without much reaction. He opened the system panel, where a new record was displayed: a new node in the commercial space mission chain has been unlocked, the overall recovery technology has been completed, and the technology enhancement continues to take effect.

He closed the interface, picked up the launch site selection report, and found that the plan for the second launch site had reached the final confirmation stage, with three candidate sites in the low latitudes along the coast.

The foundation has been laid for the goal of launching twelve times in a single month.

He turned to the first page and began to read.