Private space launch corporations INNOSPACE said it completed development of core technology for the liquid methane engine to be applied to its next launch vehicle and succeeded in a long-duration ground hot-fire test.
INNOSPACE said on the 4th that it completed core technology development for the 0.4-ton-thrust liquid methane engine "LiMEK-04," which will be applied to the kick stage of the next launch vehicle "Hanbit-Micro," and successfully conducted a 420-second ground hot-fire test.
A kick stage is a space propulsion system that separates after the second-stage engine of a launch vehicle finishes burning and precisely sends the payload to its target orbit. The technology developed this time is the "bipropellant regeneratively cooled methane engine combustor technology" applied to the LiMEK-04 engine.
Regenerative cooling is a technology that protects the combustion chamber from the high temperatures generated during engine combustion and maintains stable combustion. It is considered a key factor that affects engine durability and performance and launch vehicle efficiency.
Conventional methane engines have mainly applied a monopropellant regenerative cooling method that uses only liquid methane as the coolant. This method requires high propellant supply pressure to secure sufficient cooling performance, creating a burden to design the propellant tanks and supply systems more robustly. As a result, there was also a limitation that it could lead to an increase in launch vehicle mass.
The bipropellant regenerative cooling technology developed by INNOSPACE uses not only liquid methane as the fuel but also liquid oxygen as the oxidizer in the cooling process. The company said this increased coolant flow by about 3.0–3.4 times compared with the conventional method. It can secure cooling performance even under relatively low pressure conditions, contributing to weight reduction of the propellant tanks and supply systems.
INNOSPACE conducted a 237-second ground hot-fire test last May for the 0.4-ton-class methane engine combustor for the Hanbit-Micro kick stage. It then completed a 420-second long-duration ground hot-fire test this May. The company said the test confirmed the engine's durability and stability and verified its applicability to an actual launch vehicle.
Chief Executive Kim Su-jong of INNOSPACE said, "Small launch vehicles are highly sensitive to mass, so structural light-weighting technology has a significant impact on payload performance and launch service competitiveness," adding, "This technology has potential applications not only for the kick stage but also for methane engines for future reusable launch vehicles and space exploration propulsion systems."
Meanwhile, INNOSPACE has been conducting cause identification, related parts upgrades, and process improvements since the first commercial launch mission of "Hanbit-Nano" in December last year ended early. It is currently undergoing launch license review by the Korea AeroSpace Administration and, after the final approval process, plans to pursue a follow-up launch within the third quarter of this year.