[단독]Eight months postponement of the launch of the Nuri… caused by defects in front and rear fuselage parts

The delay in the development schedule of the Korean launch vehicle (Nuriho, KSLV-II), which was originally scheduled for a test launch last month, was confirmed to be affected by defective parts supplied by Lotte Group affiliates. Korea Aerospace Research Institute (Hang Woo-yeon) has improved the defect rate by entrusting the parts to other mid-sized companies.

According to the Ministry of Science and ICT (Ministry of Science and Technology) on the 7th, after a comprehensive inspection of the Nuri launch plan from September to November last year, parts problems were revealed, and the National Space Commission was opened and the Nuri launch plan was postponed.

At this time, there are two main parts that have been problematic in the comprehensive inspection. It was the front fuselage, which is a component that connects the bottom end of the Nuriho (first-stage rocket) and the second-stage rocket, and the rear fuselage that connects the body of the rocket and the engine.

The front fuselage is manufactured using thin and light fiber composites. Initially, this part was manufactured by Deck Airlines, a material company. Deck Air is a Lotte Group affiliate that is 100% owned by Lotte Chemical.

The problem was the defect rate of the parts supplied by Deck Airlines. An official who was involved in the Nuriho project at the time said, “To connect the first-stage rocket with a diameter of 3.5m and a two-stage rocket with a diameter of 2.6m, the purity of the parts is important. It was evaluated that it was difficult to withstand the load of the arc and its durability was poor.” He explained, “Because it is a very precise work, there may be some defect rate during the manufacturing process, but the defect rate of Deck Airlines was not enough.”

The government eventually replaced the component manufacturer with Korean fiber. On the 25th of last month, two months after the supplier was replaced, the Nuri-ho succeeded in a combustion test for 100 seconds.

Hang Woo-yeon explained, “According to the regulations, we imposed a late compensation on Deck Airlines (a cost to be borne in case of non-fulfillment of contractual obligations).” However, he did not disclose the amount of down payment or late prize money.

However, in the process, the national space project, which invested 1,9572 trillion won, was postponed for eight months. Hang Woo-yeon said, “We secured additional labor and technical expenses due to the delay of the launch of the Nuri, but hardware expenses were not added separately.”

Tech Aviation is also in charge of manufacturing other parts for the Nuri. The rear fuselage of the second-stage Nuri-ho rocket, the cable cover of the first, second, and third-stage rockets, and some panels design, manufacture, and assembly are still in progress. According to Hang Woo-yeon, of the parts supplied by Deck Airlines, other parts except for the front fuselage had no major quality problems.

Regarding this, Deck Airlines said, “The Nuri development project is a national project in which a number of companies participate at the same time led by the government,” and said, “It is impossible to comment on the production process of the Nuri, a security matter.”

The rear fuselage connecting the body of the rocket and the engine was also a problem while supporting four 75t-class engines mounted at the bottom of the first-stage rocket. When a load test was performed through the structural test equipment, this part had signs of damage, such as being slightly crushed when a load slightly exceeding the load (300t) that the Nuri was applied during flight was applied.

S&K Airways was in charge of this task, and it was found that there were no problems in the manufacturing process. After reinforcing the design of the parts, Hang Woo-yeon requested S&K Air to remanufacture.

According to Hang Woo-yeon, most of the parts are made by hand on the Nuri. Therefore, in order to replace parts, the rocket must be dismantled and reassembled. This is the background of 8 months delay due to two parts.

“The trial and error experienced in the process of independently designing and manufacturing the Nuri,” said Tak Min-je, a professor of the Department of Aerospace Engineering at the Korea Advanced Institute of Science and Technology (KAIST). It is important.”

“The launch schedule of the Nuri was delayed by about 8 months due to technical problems,” said Lee Chang-yoon, director of the Ministry of Science and Technology, “but the success of the first-stage rocket combustion test last month gave researchers confidence.” I will actively support it,” he said.

Reporter Moon Hee-cheol [email protected]