China has conducted a second test flight of a reusable rocket engine which is similar to the one used by SpaceX helping the country close its technological gaps with the United States on low-cost space flight.
The rocket engine which uses liquid oxygen and kerosene was recently put to the test in a launch and returned back to Earth in one piece according to the Xian Aerospace Propulsion Institute in a statement via its WeChat account on Tuesday.
No further details of the flight were discussed even though the institute said it was the first time China had reused a rocket engine.
The institute is a subsidiary of the state-run China Aerospace Science and Technology Corporation.
Back in the year 2021, the engine was first used as the main power system for launch and following an inspection and maintenance, the engine was reassembled for the latest flight.
“This successful verification means that our engine reuse technology has entered the practical stage. That enables us to pay more attention to the high reliability, low cost, and high performance of the engine,” Zhang Xiaojun, head of the institute, was quoted as saying in a China News Service report on Wednesday.
China is being credited for its leading role in developing air-breathing engines for hypersonic flight even though it’s still behind on reusable rockets as it uses traditional engine technology.
The liquid oxygen and kerosene rocket engine provides the main power source for space travel.
Carrying their own oxygen they can function either in the air or in a vacuum. They also have an advantage on thrust, the fuel is non-toxic and they create little pollution.
The engine can also be used for vertical take-off and landing similar to the Merlin-1D engine used on the Falcom 9 rockets.
According to the Xian institute statement, scientists are working on the engine in order to overcome technical challenges in every flight stage with the first being the repeat ignition technology needed for a vertical landing.
Before a second ignition, the engine often requires to be cooled off and purged in order to clear away combustion and residual fuel from the first flight.
The institute said it had achieved three uninterrupted ignitions during ground testing and found a method to purge and pre-cool the tank.
The landing process is also challenging because, during the return flight, the vehicle gets lighter due to the gradual reduction of the remaining propellant.
There is some engine thrust required in order to achieve controlled deceleration or soft landing.
The institute said this was also part of ground testing and an earlier test with a Long March 8 rocket.
With repeat use and ignition, the engine also needs to be protected against impact and heat, as outside air pressure changes in the return stage. That means sealing materials are important, and the institute said its protective measures had proven effective during the second test flight.
There is a plan to assess the reliability of the engine when it’s reused and the institute made it known that it had developed and adapted online real-time technology in order to evaluate the engine after a mission which would provide a low-cost and fast way to carry out inspection and maintenance on the rocket engine.
“The progress China has made in repeatedly using the liquid oxygen and kerosene engine is of great significance,” Zhang told China News Service.
He said the second test flight had provided a “valuable experience and paved the way for the subsequent development of a larger thrust reusable liquid oxygen and kerosene engine in China”.
“That will be a big leap from ground zero,” he added.