Liquid oxygen-kerosene rocket engine: the "new engine" supporting China's space program

Author: Huang Xianghong Duan Yuechu

In the journey of human exploration of the universe, the rocket engine is undoubtedly the most critical "heart". The liquid oxygen-kerosene rocket engine, with its unique charm and excellent performance, has become a powerful booster for China's aerospace to move towards the stars and the sea. Looking back on January 19, 2025, it was a day that made Chinese aerospace people excited. In the Baolongyu test area of ​​the 165th Institute of the Sixth Academy of China Aerospace Science and Technology Group, my country achieved the "three tests a day" of the liquid oxygen-kerosene rocket engine for the first time. At the test site, the huge roar was deafening, and the blazing flames ejected from the engine illuminated the sky, as if announcing to the world a new breakthrough in China's aerospace propulsion technology. The significance of this achievement cannot be overstated. It marks that my country's new generation of carrier rocket main power engines have achieved a qualitative leap in the test verification capability to adapt to mass production and delivery, and has also laid a solid foundation for the high-density launch of the Long March series of rockets in the future.

1. Excellent performance, showing the "hard core" strength of aerospace

The advantages of liquid oxygen-kerosene rocket engines are reflected in many aspects. Take thrust for example. The 120-ton liquid oxygen-kerosene engine uses the world's top high-pressure regenerative cycle system, which is like injecting powerful "magic" into the engine. It greatly increases the engine's thrust by more than 60% compared to my country's existing Long March series of launch vehicle engines, and its carrying capacity is increased to about 3 times the original. Imagine that this is like replacing a truck that can only carry a small amount of cargo with a super powerful engine, allowing it to easily carry more supplies and go farther. With such a powerful thrust, my country's rockets can carry more scientific research equipment and spacecraft into space, providing a strong guarantee for the realization of grand goals such as manned lunar landing and deep space exploration.

In terms of environmental protection, the liquid oxygen-kerosene engine can be called a "green pioneer". The liquid oxygen and kerosene it uses are both environmentally friendly fuels, and the products after combustion are only water and carbon dioxide. Compared with traditional rocket engines, this is a world of difference. In the past, engines that used highly toxic propellants were like "time bombs" during production, storage and use. They posed great safety risks and caused serious environmental pollution. The emergence of the liquid oxygen-kerosene engine means that we no longer need to worry about environmental pollution on the road to space exploration, and can move more safely into the depths of the universe.

Cost-effectiveness is also a highlight of the liquid oxygen-kerosene engine. Kerosene is relatively cheap, and its cost is about 60% cheaper than conventional engine propellants. Each launch can save more than 10 million yuan in propellant alone. This is not a small amount for the aerospace industry. Lower costs mean that we can use the same funds to carry out more aerospace projects and make more dreams come true.

2. Unique advantages make it the "new darling" of aerospace

Compared with other types of rocket engines, the liquid oxygen-kerosene engine has many unique features. From the perspective of propellant, it is completely different from the traditional nitrogen tetroxide/undimethylhydrazine engine. The propellant used in traditional engines of this type is highly toxic and requires extreme caution during operation. Once a leak occurs, the consequences are disastrous. The propellant of the liquid oxygen-kerosene engine is both safe and environmentally friendly, and the risks are greatly reduced during production, storage and transportation.

Compared with hydrogen-oxygen engines, liquid oxygen-kerosene engines have obvious advantages. Although hydrogen-oxygen engines have a higher specific impulse, the storage and transportation of hydrogen is a headache. It requires special low-temperature storage equipment and has extremely high requirements for safety measures. Liquid oxygen and kerosene are relatively easy to store and transport at normal temperature and pressure, which undoubtedly brings great convenience to practical applications.

In terms of circulation, the high-pressure regenerative cycle system used by the liquid oxygen-kerosene engine is the key to its excellent performance. This circulation system allows the propellant to burn fully in the combustion chamber, just like letting every drop of fuel release the maximum energy. However, its structure is quite complex, and the requirements for design and manufacturing process are almost harsh. To create such a high-performance engine, countless aerospace researchers need to study and tackle key problems day and night.

3. Performance parameters, witnessing the "wisdom" of aerospace

The performance parameters of my country's liquid oxygen-kerosene engines are very impressive. Taking the YF-100 engine as an example, its thrust on the ground is about 1200kN (120 tons), and in a vacuum, this number is increased to about 1340kN. The ground specific impulse is about 2942m/s, and the vacuum specific impulse is about 3286m/s. The pressure in the combustion chamber is as high as 18MPa, the consumption of oxidizer reaches 296.39kg per second, the consumption of combustion agent is also 113.31kg per second, the total flow rate of propellant is 409.70kg per second, and the mixing ratio of propellant can be flexibly adjusted between 2.6 and 2.7. The nozzle area ratio is 35, and the thrust chamber nozzle area is 1.406m². As a single-chamber engine, the YF-135 liquid oxygen-kerosene engine has a sea level thrust of 360 tons, a specific impulse of 321 seconds, and a thrust-to-weight ratio of up to 90. Behind these seemingly cold numbers are the wisdom and sweat of countless aerospace workers. They have witnessed the rapid development of China's aerospace industry in the field of power technology.

As a space enthusiast who has been paying attention to the aerospace industry for a long time, I am deeply attracted by the charm of liquid oxygen-kerosene rocket engines. Whenever I see a rocket carrying a liquid oxygen-kerosene engine taking off, I can't help but feel excited. It is not only a symbol of China's aerospace technology strength, but also a manifestation of the human spirit of exploring the universe. From the initial difficult exploration to the major breakthrough today, the development of liquid oxygen-kerosene rocket engines is full of challenges and miracles. I believe that in the future, with the continuous advancement of technology, it will continue to support China's aerospace dream and move towards the deeper and more distant universe.

Liquid oxygen-kerosene rocket engines, with their incomparable advantages and excellent performance, have become the mainstay of China's aerospace development. They have brought us one step closer to the mysteries of the universe and have also allowed the world to see the rise and development of China's aerospace industry.