Innospace, a domestic private space company, has succeeded in a ground firing test of a liquid-methane rocket engine that reduces weight compared with existing ones. Innospace plans to equip its small launch vehicle currently under development, ‘Hanbit-Micro’, with the engine.

On the 3rd, Innospace announced that it had succeeded in a ground firing test of the 0.4-ton-class engine ‘LiMEK-04’, which uses liquid methane as fuel. The burn duration was 420 seconds. Success in the ground firing test means that the core technologies of the methane engine have been completed.

This engine is scheduled to be installed on the ‘kick stage’ of Innospace’s Hanbit-Micro launch vehicle. Hanbit-Micro is a 22.5ｍ launch vehicle that places small satellites at an altitude of 500㎞. The kick stage, a mini rocket mounted at the very top of Hanbit-Micro, is responsible for delivering the satellite precisely to its designated orbit.

Unlike kerosene (jet fuel), a rocket fuel widely used worldwide, methane leaves no soot after combustion. That makes it suitable for reusable launch vehicles. After recovery, it can be relaunched quickly without spending a long time on extensive engine cleaning. SpaceX has for years been conducting test launches of ‘Starship’, a representative launch vehicle that uses methane engines. Development of methane engines is accelerating domestically as well.

The distinguishing feature of the Innospace methane engine that succeeded in this ground firing test is its reduced weight. The approach was to improve the engine cooling method. Conventional methane engines used only liquid methane (minus 161 degrees Celsius) as the coolant to cool the engine. Therefore, to secure sufficient cooling performance, high pressure was required to circulate the methane vigorously, and the weight of related components increased to ensure durability.

However, the Innospace engine also uses liquid oxygen (minus 183 degrees Celsius) as a coolant. The amount of coolant has increased by about three times. This enables stable cooling performance even at relatively low pressure, allowing components to be made lighter.

Kim Su-jong, CEO of Innospace, said, “In small launch vehicles, the technology to reduce structural weight is a key factor that determines payload performance and the competitiveness of launch services,” adding, “We expect this technology to be widely applied in the field of space propulsion systems.”