The turbopump has passed the medium test assessment.

In early January 2019, the core component of Jiuzhou Cloud Arrow's "Lingyun" engine (with a thrust of 12 tons)—the coaxial turbopump—successfully completed low-temperature medium testing and evaluation. This test specifically assessed the design accuracy of the clearance between rotating and stationary components within the turbopump, as well as the multi-condition adaptability of its sealing, bearing, and axial force designs. Key performance parameters of the turbopump's critical components were obtained during the test. Throughout the experiment, the turbopump exhibited stable speed, pressure, and temperature curves. Post-test inspections revealed no abnormalities in the turbopump, confirming that the test objectives had been fully achieved.

This experiment is of extraordinary significance. The turbopump for the Lingyun engine marks the first domestically designed and manufactured turbopump to successfully pass rigorous testing in China's commercial aerospace market. The successful completion of this test breaks the previous situation in China's commercial space liquid rocket engine sector, where various combustion devices have emerged but no high-speed rotating machinery has yet made its debut on stage. With this milestone, all major components of the Jiuzhou Yunjian Lingyun engine—namely, the igniter, gas generator, thrust chamber, turbopump, as well as the main and auxiliary system valves and thrust regulation mechanism—have now completed their respective component-level tests.

In the field of liquid propulsion, there is a widely accepted consensus: "He who masters the engine wins the rocket, and he who controls the turbopump secures the engine." As the heart of a liquid-propellant rocket engine, the turbopump is the only high-speed rotating mechanical component among the engine's primary assemblies. Its critical role lies in pressurizing the low-pressure propellants stored in the rocket tanks and delivering them in real time to the thrust chamber and auxiliary systems, where they are combusted to generate the high-temperature gases necessary for propelling the vehicle out of planetary gravity. Do not underestimate the seemingly simple function of "pressurization." To achieve optimal performance of the entire engine system, the turbopump must operate within a multitude of stringent constraints—ranging from temperature and pressure limits at the pump and turbine inlets, flow rate restrictions, weight limitations, to enduring harsh thermal and vibrational environments. Ultimately, it must also deliver an exceptionally high head pressure. In essence, designing a turbopump is akin to an artisan dancing while wearing shackles—every decision and innovation must carefully balance these rigorous demands. Under such exacting conditions, designers must meticulously address a wide array of challenges, including pump dynamics, turbine performance, rotor dynamics, sealing mechanisms, bearing design, axial force balancing, heat transfer, structural statics and dynamics, material selection, and manufacturing processes. Only through the careful integration of these complex considerations can engineers successfully develop a high-quality turbopump capable of meeting the demanding requirements of modern liquid rocket engines.

The Lingyun engine's turbopump was initially designed with commercial aerospace engines and commercial launch services as its primary application scenarios. Given that liquid oxygen/methane exhibits relatively similar physical properties, the final decision was made to adopt a coaxial turbopump design after comprehensively evaluating factors such as reliability, cost, and weight. Compared to dual-turbine pumps for oxidizer and fuel, the coaxial design significantly reduces the number of components, lightens the overall weight of the turbopump, and enhances its reliability. The Lingyun engine utilizes a dual cryogenic propellant combination—liquid oxygen and methane—with pump-end temperatures as low as -190°C. Meanwhile, the driving gas temperature in the turbine end subsystem reaches over 700°C. Operating at these extreme conditions—where one side is icy cold while the other is scorching hot—the turbopump must maintain high-speed operation at tens of thousands of revolutions per minute. Under such challenging thermal environments, material properties and structural behaviors undergo significant changes due to the drastic temperature variations and gradients. These factors necessitate meticulous consideration and stringent control throughout the design and manufacturing processes of the turbopump.

To minimize structural weight as much as possible, every internal design detail of the Lingyun engine's turbopump was meticulously reviewed and refined during the design process. Building upon existing expertise, innovative approaches were also employed. After multiple rounds of iterative optimization, the final design achieved a structural weight of just 31 kg for this turbopump, which delivers an output power exceeding 1 MW. Moreover, the turbopump boasts an impressive power density of 33 kW/kg—a highly challenging technical benchmark, especially for engines in the 10-ton thrust class. By enhancing the power density while maintaining equivalent thrust levels, the turbopump significantly reduces overall engine weight, thereby boosting the payload capacity of customers' launch systems. This aligns perfectly with the evolving demands of the commercial space market.
Over the past year, the team at Jiuzhou has steadily advanced on the path of developing commercial liquid-propellant engines. In April 2018, the turbine pump for the Lingyun engine of Jiuzhou Yunjian successfully completed its conceptual design review; by the end of May, detailed design was finalized, followed by the completion of tooling and fixture designs in June. Full-scale production commenced in July, and by November, the turbine pump assembly was fully ready. Early December saw the successful completion of the turbine pump assembly process. Following medium tests, this turbine pump will proceed to participate in subsystem-level integration testing as well as full-engine hot-fire tests, further evaluating its adaptability to the engine's deep thrust-vector control capabilities, along with the operational compatibility and reliability of all component assemblies. Looking ahead, the Jiuzhou team remains committed to upholding and promoting the spirit of dedication and innovation that has long defined China's aerospace industry. With unwavering focus and relentless effort, we aim to leverage our strengths and expertise, striving to become a leading global provider of liquid propulsion systems tailored for the commercial space market. Ultimately, we aspire to serve as a valuable complement to China's aerospace endeavors, contributing meaningfully to humanity's ongoing quest to explore the cosmos.