20 satellites in one rocket! The successful launch of Jielong-3 injects new momentum into commercial aerospace!

At 3:24 on December 6, the Jielong-3 carrier rocket ignited and lifted off in the sea near Yangjiang, Guangdong, and successfully sent the satellite Internet technology test satellite into the predetermined orbit. The launch mission was a complete success. The Jielong-3 is a commercial four-stage solid rocket designed for the rapid networking and launch needs of future satellite constellations. It has made breakthroughs in many key technologies and has the ability to launch 20 satellites with one rocket. Its comprehensive launch cost is currently the best in China, and it will surely inject strong new momentum into domestic commercial space launches.

Long March 3 rocket

Solid rocket advantages are fully utilized

As we all know, solid rockets are relatively simple in structure and have advantages such as high reliability, short fulfillment cycle, and simple launch site support. The Jielong-3 rocket has the characteristics of strong carrying capacity, large fairing envelope space, diversified launch methods, good economy, high launch efficiency, and short fulfillment cycle, which fully demonstrates the multi-faceted advantages of solid rockets.

Public information shows that the total length of the rocket is 31.8 meters, the maximum diameter of the rocket body is 2.65 meters, the take-off mass is 140 tons, the carrying capacity of 1.5 tons in the 500-kilometer sun-synchronous orbit, and it has a 2.9-meter diameter and 3.35-meter diameter fairing. It can be launched at sea and from land vehicles, and has strong mission applicability.

The Jielong-3 rocket is in transit

As the saying goes, "the stronger the power, the bigger the space stage." The Jielong-3 rocket uses a high-performance fiber-wound composite shell integral solid engine with the largest charge and thrust in China. The engine has a diameter of 2.65 meters, a charge of 71 tons, a thrust of 200 tons, and uses a number of new technologies, with comprehensive performance reaching world-class levels.

Through a multi-pronged approach of technical and economic integration, the research and development team of China Long March Rocket Co., Ltd. (hereinafter referred to as China Rocket Company) of the First Academy of China Aerospace Science and Technology Corporation has achieved controllable design costs and improved the comprehensive performance of engine products while ensuring product reliability. In this mission, the Jielong-3 rocket completed the first hot launch of a Chinese rocket at sea, achieving a leap from cold launch at sea to hot launch at sea.

Due to the increase in the size of the rocket body, the Jielong-3 rocket innovatively adopted a frame-guided sea-based hot launch solution, overcoming technical difficulties such as launch stability, launch safety, gas flow guidance and thermal protection design. While ensuring launch safety, it effectively shortened the launch process and reduced launch costs.

During this mission, the appearance of the Jielong-3 rocket was also talked about with great relish - "big head and thin neck". It turns out that the maximum diameter of the Jielong-3 rocket body is 2.65 meters and the minimum diameter is only 2 meters. The development team used a 3.35-meter diameter fairing, which can provide a larger envelope space for the payload compared to solid rockets of the same size. However, this configuration brought great troubles to the rocket structure load design, flight attitude control and complex noise and vibration environment design. The development team worked hard to prepare a more "comfortable" space for the satellite.

The integrated test, launch and command system of the Jielong-3 rocket is also more concise and intelligent. It is understood that the front and back ends of the ground test, launch and control system are fully integrated in the front-end test and launch control cabin and the back-end integrated command and control cabin. The system has a high degree of integration and intelligence, and can achieve "one-click" launch from a laptop.

The successful launch of the Jielong-3 rocket further verified the advantages of integrated production, manufacturing and launch - reducing the complex transportation links between rocket production and launch, shortening the launch chain and greatly improving launch efficiency.

It is reported that the final assembly and testing of the Jielong-3 rocket was carried out at the solid rocket final assembly and testing base of China Rocket Company in Haiyang City, Shandong Province, in a batch production and storage mode. When executing the launch mission, the satellite-rocket docking and fairing docking were carried out; after the necessary tests, the rocket was transported as a whole to the launch ship at the offshore launch home port (Haiyang Port), with a transportation distance of no more than 6 kilometers and a transportation time of no more than 2 hours; after the launch ship-borne rocket was transported to the target sea area, it entered the launch process. The entire process generally takes no more than one week, and the efficiency of a single launch is greatly improved, and a high-frequency launch once a week can be achieved.

It is worth mentioning that during the development process of the Jielong-3 rocket, a large number of autonomous and controllable industrial software such as "Tianxun", "Tianxing", "Tianji" and "Tianxiang" were adopted, realizing the transformation from foreign industrial software to autonomous control, and from ground physical verification to simulation design, reducing a large number of physical ground tests and effectively improving design efficiency.

Thermal launch at sea overcomes difficulties

This Jielong-3 rocket mission achieved the leap for China's rockets from cold launch at sea to hot launch at sea.

Launching rockets at sea has many advantages. First, the launch platform at sea can be deployed flexibly, such as choosing to launch in the sea near the equator, making the most of the earth's rotation speed to send the rocket into orbit, increasing the rocket's payload, and saving the rocket's fuel. Second, the launch range at sea is wide, and the rocket debris can splash on the sea surface, avoiding densely populated areas such as cities, and the landing area is safe.

At present, the advantages of safe, flexible and efficient sea launches have been verified through domestic rockets of different models, and sea launches may become more normalized. More professional Chinese sea launch ships are under construction, striving to achieve multiple launches at sea in one go. Fixed sea launch platforms are being demonstrated in parallel, which can sustainably reduce the requirements for rockets for sea launches, and greatly improve the economy and flexibility of sea launches through the "fixed + mobile" mode. Not only that, Chinese rocket companies are also actively exploring the sea launch capabilities of liquid rockets, truly realizing more complete sea launch capabilities such as "both hot and cold", "solid and liquid compatible", "fixed + mobile", and "multiple launches at sea in one go".

The Jielong-3 rocket is being prepared on the launch ship

So how do we distinguish between "cold" and "hot"? The so-called "cold launch" means that the rocket is first ejected from the launch tube, and then ignites and takes off in mid-air. The high-temperature tail flame of the rocket will not burn the launch platform. The Long March 11 rocket adopts this launch method. The so-called "hot launch" means that the rocket ignites and takes off directly from the launch platform without the ejection process. The vast majority of rockets in my country adopt this launch method.

On the surface, hot launch at sea seems to be simpler than cold launch at sea because it lacks the ejection step, but in fact it is not. Direct ignition of the rocket will produce a strong reaction force, affecting stability, and the high-temperature tail flame of the rocket will also test the bearing capacity of the launch ship and launch equipment. How to solve these problems?

When watching the Jielong-3 rocket mission video, careful viewers may find that the rocket is wrapped in a rectangular "cage" before takeoff. This "cage" is the guide frame. The sea is windy and the waves are high. If it does not rely on external support, it is difficult for the rocket to stand steadily on the launch ship. Therefore, during cold launch, the launch tube supports the stability of the rocket; during hot launch, the rocket is "held" by the guide frame, so that the rocket will not become unstable and overturn due to sea conditions.

In order to solve the problem of high temperature resistance during hot launch of rockets at sea, the developers added a 15-meter-long and 10-meter-wide launch support platform at the rear of the launch ship. With the help of this platform, the rocket tail flame is guided from top to bottom to the horizontal sides, which greatly reduces the impact of the rocket tail flame on the launch ship and launch equipment.

In addition, the developers also added a second layer of insurance to the launch equipment - adding a protective layer to the core components and adding protective steel plates to the parts that are subject to high heat flux density. The ultimate goal is that after the rocket is launched, the main structure of the equipment will not be affected and it can perform the mission again after simple maintenance.

Since there are many problems to be overcome in hot launch at sea, why should we try it? Because compared with cold launch at sea, hot launch at sea is more economical. The guide frame is obviously more cost-effective than the launch tube, and there are fewer disposable consumables, which can be said to maximize the value. With the successful hot launch of the Jielong-3 rocket at sea, we are expected to see more models of rockets make attempts in this regard.

Business needs drive comprehensive upgrades

With the growing demand for space information and the booming commercial space industry, rockets are facing new requirements for low-cost, large-scale, rapid networking and launch. China Rocket Company has adopted a commercial model and a technological and economic integration approach to achieve serial development based on the Long March 11 rocket and create the Jielong 3 rocket, which is committed to providing low-cost, batch, and high-frequency launch services for low-orbit satellites.

The basic starting point for a commercial rocket is to meet the needs of commercial use to the greatest extent possible. The primary indicator of the Jielong-3 rocket is high cost performance, and the cost of rocket manufacturing and launch is controlled as much as possible. The price of the entire rocket launch service per kilogram of payload does not exceed US$10,000.

Cost control is not easy, and the development team has made many innovations in management models. First, with the target cost as the first constraint, iterative optimization of the plan and cost is carried out, and the technical plan is determined according to the principle of "optimal cost, simplest process, and shortest process". Second, explore and form a new model of commercial rocket quality management with differentiated management as the core, and formulate different levels of quality management strategies for different levels of products, processes, and risks. Third, through a series of measures such as mass production, optimization of production processes, shortening of launch chains, and strategic cooperation for win-win results, the cost of rocket production and launch is reduced.

The Jielong-3 rocket is assembled in sections

Product universalization and modularization are also effective means of reducing costs. The research and development team has made extensive use of Long March series rocket technology and a large number of simulation technologies to achieve a certain degree of universality in single machines, tooling, equipment, and facilities, further reducing component costs, shortening the delivery cycle of rocket bodies, and addressing the "gap" in the market for commercial launches.

In addition, a short fulfillment cycle is also important. The development team has done two main things: on the one hand, through the design concepts of rocket body de-tasking and flight software multi-dimensionalization, it serves the mass production of rockets; on the other hand, in view of the "short-term" work related to satellites and rockets, it adopts design methods such as rapid integrated design of satellites and rockets and parallel engineering to effectively break through key bottlenecks. In this way, the fulfillment cycle can be compressed to 3 to 6 months.

In short, it took only 20 months from the project development to the successful first flight of the Jielong-3 rocket, which means that China Rocket Company has explored a new model for the rapid development of commercial rockets. It is reported that China Rocket Company will start the construction of the second phase of the general assembly and test plant in Haiyang, Shandong, and plans to reach an annual production capacity of 20 rockets and a turnover storage capacity of 3 rockets by the end of 2023.

The Jielong-3 rocket was branded as a commercial rocket when it was first launched. During the market development process, China Rocket Company established a regular negotiation mechanism with customers and a strategic alliance with high-quality customers. During the launch service phase, the company exerted its strong market resources and pre-sales capabilities to strengthen collaborative design with satellite parties. During the satellite constellation demonstration phase, the company made full use of the Jielong-3 rocket, Long March 2C rocket, Long March 11 rocket, etc. to provide satellite parties with flexible, economical and efficient integrated launch solutions, improve satellite networking efficiency and reduce launch costs.

Around the Jielong-3 rocket, China Rocket Company has also explored a series of brand value-added services, such as rocket body advertising, brand collaboration, science education, cultural tourism and cultural creation.

The successful maiden flight of the Jielong-3 rocket has further improved the spectrum of related solid rocket models. The carrying capacity of the 500-kilometer sun-synchronous orbit covers 200 kilograms to 1.5 tons, and the diameter of the fairing covers 1.2 meters to 3.35 meters, with a more reasonable carrying capacity gradient. At the same time, through de-task design, batch production, integrated services, and integrated launch, it can provide satellite customers with safer, more flexible, economical, and efficient launch services.

In the future, the development team will continue to optimize and upgrade the Jielong-3 rocket, further closely follow the current and future low-cost, batch, and high-frequency launch requirements for low-orbit satellites, and determine the performance indicators and usage modes of the rocket. For example, by reducing the weight of the structure to increase the carrying capacity, replacing the liquid upper stage to improve the launch adaptability, etc., strive to provide commercial satellite customers with better quality and cheaper launch services.

The Jielong-3 rocket is not the "end" of the series. China Rocket Company is currently demonstrating the Jielong-4 rocket with greater thrust, which will have a carrying capacity of 2.5 tons to a 500-kilometer sun-synchronous orbit. The development team will reduce development costs, enhance market competitiveness, and better meet the diverse needs of satellite customers through measures such as modular combination of solid engines, unified onboard electrical systems and ground test, launch and control systems.