China Sets Up Three Technical Approaches for Reusable Rocket Engine

“China is continuously conducting technological research on reusable rocket engines, represented by liquid oxygen hydrocarbon engines, and has established many key technologies such as continuous repeated thermal testing,large-scale thrust adjustment, repeated starting, reuse and immediate processing.” According to LIU Zhirang, Vice President of the Academy of Aerospace Liquid Propulsion Technology (AALPT),who announced the improvement of reuse technology and adaptability of the main engine.

Compared with the single-use rocket, what are the requirements for the reusable rocket? “The return and recovery process places high demands on the adjustment capacity on rocket engine thrust. At present, the rocket engine has the adjustment ability to reduce the thrust to 70% of that rated.The thrust needs to be reduced to 40% rated 40% or even 30% to meet the recovery requirements. The larger range of thrust adjustment means the more difficult design.” LIU Zhirang explained.

China has formulated a Reusable Launch Vehicle (RLV) Development Plan and set up three technical approaches according to its short-, medium- and long-term goals. LIU Zhirang said that AALPT focuses on the reuse of space liquid propulsion and promotes research under the guidance of the plan.

First is to conduct main engine reuse technology research and improve adaptability based upon rocket configurations that are currently in service, finish the recovery verification in the short term, to assure the safety of the landing area, and realize controllable recovery in the landing area and partial reuse by around 2025.

Second is to conduct research on reusable liquid oxygen hydrocarbon engines based on newly developed rocket configurations, support vertical and horizontal recovery plans, have the ability to reuse the first and second stages of the rocket in the medium term, promote the formation of two-stage-toorbit space transportation industry and achieve the engineering application of a reusable two-stage transportation system by 2030.

Third is to conduct research on an air-breathing combined engine based on horizontal takeoff and landing RLV configuration, and realize the engineering application of a single-stage-to-orbit launch vehicle.

A rocket engine inherently operates in a severe operation condition which brings a great challenge for reuse. “A single-use rocket may finish its mission in a few minutes, while the working life of a reusable engine needs to be increased.” LIU Zhirang explained, “this requires the engine design concept adapting from just strength to long-life,enhance technologies in the areas of structural reliability, health management,maintenance and sensors, life prediction and evaluation.”

In addition, AALPT has conducted research on combined cycle propulsion technology and ground integration tests aimed at the future. The successful development of combined cycle propulsion can support the need for a horizontal takeoff and landing RLV which will improve the ability to access and leave space quickly.

“The technology is intended to combine that of the aero-engine, ramjet engine and rocket engine to give full play to their advantages in different environments.” LIU Zhirang said. All the three propulsion forms are being constantly developed. It will be a great innovation if they can be combined together. However there are still many difficulties to overcome to enable the maximum benefits for the whole system, along with the optimization of the orbit and net economic benefits.