Naroho

The Naro-ho or KSLV-I (Korea Space Launch Vehicle-I) was developed by the Korea Aerospace Research Institute in 2002 according to the KSLV plan , and was developed three times in 2009 , 2010 , and 2013 . It is Korea's first space launch rocket . About KRW 500 billion was invested in the development , and the first stage rocket used the RD-151 engine developed by Energomarsh of Russia , and the second stage rocket used an 8-ton solid rocket manufactured by itself. The first and second launches failed due to unseparated fairings and air explosions, respectively, and the third launch succeeded in putting the Naro Science Satellite (STSAT-2C) into low earth orbit.

After the success of KSLV-I, Korea Aerospace Research Institute has been carrying out a plan for a rocket (KSLV-II) for launching low-orbit practical satellites with a domestically produced first-stage rocket, and as a result, in 2021 Nuriho was developed.

The name 'Naro' was selected through a national naming contest and was the first space center in Korea where a rocket was launched. The name of the Naro Space Center and Jeollanam- do, where the space center is located Goheung-gun It is derived from Oenarodo .[1] It is said that the name Narodo comes from the fact that the island looks like windblown silk when viewed from the sea . #

 more detailsNaro/Development History documentcastPlease note.

For reference, the thickness of the fuel tank is only 2 mm , and since such a tank cannot withstand its own weight or is easily damaged when empty, it is filled with helium during transportation. This tank structure has long been used to reduce the weight of rockets.[5] It is one of the commonly used methods and can collapse or collapse if it fails to maintain internal pressure.[6]

Initially, the name of the satellite created to launch KSLV-I was Science and Technology Satellite No. 2 . To be precise, two identical satellites were created to launch the first and second launches of the Naro, and were numbered STSAT-2A and STSAT-2B, respectively. The problem was initially made to prepare for the launch in 2005 according to the plan, but as the launch continued to be delayed, it went to storage for over four years. In this way, both the first and second launches, which were barely performed, failed, and both satellites could not reach orbit and were consumed.

Therefore, the newly manufactured Naro Science Satellite (STSAT-2C) for the third launch was smaller and had more simplified functions than before for reasons such as time and budget. It orbits the Earth once every 103 minutes and performs missions such as measuring space radiation, observing the space ionosphere, and verifying domestically developed space technology. Since the main mission is to confirm satellite entry into orbit and check satellite status, the expected lifespan was short at one year. It is said that it has been active for about 3 months longer than its expected lifespan and has been no longer in communication since April 2014. #

It is not an exaggeration to say that prior to the development of the Naro, Korea's space launch vehicle-related technology was at the level of a blank sheet of paper that fell short of the rudimentary level. Under such circumstances, he acquired numerous technologies directly or indirectly through cooperation with Russia. Overall, there has been tremendous technological progress, and it is judged that this will be of great help to the future development of the Korean launch vehicle .

Among them, the most prominent technologies are launch vehicle system technology and launch site ground system technology. All systems, not just space launch vehicles, are more than just the sum of their parts. From the initial design stage, it is necessary to decide what form and function to have, what parts to use for this purpose, what are the requirements for such parts, etc. It is necessary to test and verify how to assemble the parts systematically and whether the parts are gathered together and operate smoothly, etc. Even after that, how to operate the assembled system, how to establish the procedure for launching it, and overseeing the entire work A number of systematic developments, such as how to configure control techniques, are required. These technologies cannot be obtained in the form of documents or products, and can only be learned through direct implementation. Korea, along with Russia, which has world-class technology and experience, develops the development process from design → manufacturing → testing → assembly → launch operation → launch. It was learned as it was while working together.

According to the Korea-Russia task division, Russia was in charge of Tier 1 and Korea was responsible for Tier 2, but as the entire system development process was jointly conducted by Korea and Russia, the content of the task division is detailed. Simply dividing the Naro into 1st stage + 2nd stage, 1st stage is a Russian rocket and 2nd stage is a Korean rocket.

Also, a fact that is not well known, the development of a 30-ton liquid rocket engine developed by Hangwoon on its own was also carried out with the Naroho budget. This is because it was originally developed in preparation for the case where KSLV-I development was changed to independent development in the middle.[7] The development of this 30-ton class engine is the Nuri-ho 75-ton class engine . Therefore, it is said that the design similarity between the 30-ton engine and the 75-ton engine is high. Analytical Consideration of Combustor Design of Korean Launch Vehicle Liquid Rocket Engine

In addition, the Naro's two-stage kick motor design will be used as the first-stage propellant of a Korean hypersonic missile .

The fact that the plan was delayed several times during the development process can be seen as a point that should be criticized. It is said that the schedule has been constantly disrupted due to the complex international cooperation system in which Korea Aerospace Research Institute, the Russian government, and three space companies are intertwined. In fact, even if unavoidable cases such as disruptions in parts supply due to the Sichuan earthquake or interruption due to problems during launch attempts were excluded, the agreement was signed and ratified, test items were added, test schedule issues, data analysis issues, etc. until the first launch attempt. This has only been postponed 5 times.

Thanks to this, he succeeded in entering the orbit of a space launch vehicle later than North Korea 's Eunha 3, and was criticized for a long time, but he managed to save face by succeeding in the 3rd launch of Naro anyway.

One of the most famous criticisms of the Naro is the failure to transfer first-stage engine technology. However, in the first place, it was impossible to trade core technologies such as single-stage engine technology within the MTCR system between countries, and both Korea and Russia were aware of this fact from the beginning, so there was no such thing as technology transfer in the initial contract . Criticizing this is like criticizing why you couldn’t receive a technology that was impossible to receive in the first place and had no intention of receiving.

There is also criticism that it is like paying our money and testing the Russian 1st Dan instead, but this is more of a reverse understanding of the context. In fact, joint development was possible because the Russian RD-151 engine used in the first stage was still unfinished. It is also close to impossible to trade finished engines because of MTCR. Considering that the purpose of cooperation with Russia was to acquire projectile system technology through experience through a joint development process, it can be seen as beneficial to both Russia and Korea.

And although this has not been officially revealed, it appears that a significant amount of technology has been acquired indirectly through exchanges between Korean and Russian engineers. The reason why it was not officially revealed is because if this is officially announced, it would be like blatantly certifying that the MTCR was violated (...). If you look at interviews with people involved in development, you can see that in response to criticism that they have not gained anything, they want to say outright that they have learned a lot indirectly, but they seem to be unable to do so, and only give off nuance.[8] The Korean launch vehicle project continued smoothly, and this interpretation gained further support as, in an article in the JoongAng Ilbo on October 29, 2021, Cho Gwang-rae testified that the engine of the ground test launch vehicle, which was known as a model, was in fact the actual RD-151 engine . However, in 2023, after the Russian-Russian War broke out , the Korea Aerospace Research Institute revised and announced that the model rocket it received from Russia was not the original.[9] With this, the official position of the Korea Aerospace Research Institute ended with the fact that the engine itself was a model.

However, since the person who testified that he received the real engine was the director of the Korea Aerospace Research Institute and the person who led the Naro project, this position is completely incoherent. In reality, there was a behind-the-scenes agreement between Russia and South Korea to transfer the original engine and various technologies, but since the confidential information was leaked to the media in the form of a personal interview, it is highly likely that it was just removed at the institutional level.

Looking at the change in engine technology used by business since the days of KSR, you can see that it continues to change from solid (KSR-I, II) → liquid (KSR-III) → solid (top of Naro) → liquid (Nuri). , At first glance, it seems that the development of the projectile proceeded without consistency. However, in fact, this problem is due to the geopolitical problems of the Republic of Korea, which have to pay attention to the four major powers.

Solid fuel rockets have the problem that they can be used as intercontinental ballistic missiles as they are.[10] . This issue is a part in which the United States interferes a lot, and the ROK- US missile range guidelines revised in 1990 prohibited the development of any rocket system with a range of 180 km and a warhead weight of 500 kg or more. It was sluggish. This is because there is no option for space development rockets with a range of 180 km. In the end, according to these guidelines, the development of KSR-II, which was a solid, was not allowed to proceed.

In 2001, when the ROK-US missile range guidelines were revised, civilian rockets were changed to those not subject to these guidelines, but in practice, it was not possible to openly make solid fuels. This is because the four major powers surrounding the Korean Peninsula , the United States , China , Japan , and Russia , will not just watch the development of solid fuel rockets that can be used as ballistic missiles. In the end, it was because of these problems that the first stage went to liquid and the second stage went to solid. This problem was practically resolved only in 2020, when the ROK-US missile range guidelines were revised again to allow the use of solid fuel in civilian rockets.[11] Since then , this problem has been completely resolved as the ROK-US missile range guidelines were abolished in 2021.

On December 12, 2012, about two weeks after the third Naro launch attempt was suspended and the launch date was delayed, North Korea suddenly succeeded in launching the Unha 3 . Some call it the Korean Peninsula version of Sputnik Shock . It is ironic to think that the KSLV plan was initially set for 2005 as well as the satellite launch date set for 2010 after being shocked by North Korea's launch of Kwangmyongsong-1 in 1999.

However, while the launch vehicle itself was successful, the satellite actually went into orbit but did not operate. It is presumed that the Kwangmyeongseong 3 satellite, which is in orbit, is not performing its satellite function properly because it is circling the orbit while somersaulting in space. # A comparison with the Naro Science Satellite, which successfully communicated after going into orbit .

In addition, in the case of South Korea, since it uses an oxidizing agent rather than red nitric acid for peaceful development, it is relatively more difficult to launch, whereas North Korea uses red nitric acid, which can be fired at any time because it can be stored at room temperature. This means that the purpose of rocket development is different in the first place. Difference between Naro and Eunha 3

Meanwhile, around March 2012, ahead of the launch of Kwangmyeongseong-3, North Korea responded to pressure from South Korea by asking, 'Do those who can't even launch Naro have the right to criticize us?' There was a time when I dissed him by saying, However, the launch of Gwangmyeongseong 3 in April 2012, which was carried out after these words were said, failed.

Ironically, the cause of Naro 1's failure is similar to that of Eunha 2's.[13] The reason for the failure of Naro 2 is similar to that of Eunha 3.[14]