Making History: Inside the Hanwha-made Engines and Pumps That Took the Nuri Rocket into Orbit

The first mission the Nuri rocket accomplished was lifting a 300-ton body off the ground and powering it through the immense weight of Earth’s gravity. How did it do this? By channeling enormous amounts of pressure down the launch vehicle in a very short time. At the bottom of the space launch vehicle, four 75-ton engines provided by Hanwha Aerospace powered the rocket’s first big lift.

For engines to produce that much power at exactly the right time, the engines have to be supplied with large amounts of fuel at constant and high speed. The key to this lies hidden inside Nuri, with another Hanwha technology that ensures a steady supply of fuel to four powerful engines.

During a rocket launch, the launch vehicle sends fuel from the propellant tank to the engine combustor using one of two methods: pressurization or a turbopump. Pressurization sends fuel by directly pressurizing the oxidant tank and the fuel tank. But there’s a challenge with this method: as fuel and power demands increase, we inevitably need stronger and heavier tanks to bear that massive amount of pressure. Yet when it comes to launching rockets, just a few grams can change the whole game. That’s why Nuri used Hanwha Aerospace’s turbopump technology, which only requires a minimal amount of pressure delivered to the propellant tank, shaving off excess weight while delivering all the pressure needed for take-off.

As they prepared for lift-off, the four 75-ton engines emitted hot combustion gas that reaches a scorching 3300 °C to 3500 °C (5972 °F to 6332 °F). To counteract these extreme temperatures and make sure Nuri was ready for the later stages of its journey, Nuri carried with it some extremely low-temperature materials, allowing it to produce the heat it needed by bearing the extreme cold.

Each of Nuri’s three stages of propulsion was tied to its own levels of altitude, and a different amount of energy was released at each stage to help it reach its orbital target. Stage 1 lasted from 0 km to 55 km and included the initial lift-off, while Stage 2 spanned from 59 km to 243 km, and Stage 3 stretched all the way from 248 km to 701 km, pushing Nuri into the final stage of its mission where it delivered its load. At each stage, Nuri intentionally shed parts, dropping off pieces of its engine after they served their purpose, until Nuri was left alone in space.

But even when combustion for one stage ends, the enormous power gained from that stage is not lost. And since the bottom of each rocket has a higher thrust than the top, special tools were needed to prevent collision and ensure a clean separation that returned each stage safely to Earth and continued the top on its journey up.

The main players in achieving this were the ‘retro motor’ and ‘ullage motor,’ and Hanwha Corporation participated in the domestic development of both. The job of the retro motor is to block the movement of the lower part after separation, while the ullage motor adds propulsive force to the upper part of the rocket. The retro motor uses eight units when the first and second stages are separated, and two units when the second and third stages are separated. In the first stage of separation, the retro motor generates a monstrous 20-tons of thrust in about one second to push the first released stage away from the rocket in the opposite direction, while the ullage motor pushes the second stage in the direction of the flight. Even a slight error in timing can lead to a collision between stages or cause the engines to deviate from the orbit. Nuri had only a short flight window, and during that window it was crucial to ensure a clean and clear separation of stages, so that the upper and lower ends could both reach their goals.