• Journal of the Korean Society of Propulsion Engineers
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• v.25 no.3
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• pp.101-112
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• 2021

SpaceX shows various strategies such as constructing various payload portfolio through the reuse of Falcon 9 and Falcon Heavy, constructing the launch vehicles using one type of engine, the transition from kerosene engine to methane engine, and the use of 3D printing. In this study, launch vehicle proposals that can cover a variety of payloads and trajectories from KOMPSAT to GEO-KOMPSAT were constructed, and ten launch vehicles using kerosene gas generator cycle engine, kerosene staged-combustion cycle engine, and methane staged-combustion cycle engine were reviewed. Of the ten launch vehicles, the reusable launch vehicle using a 35-ton methane engine was rated as the best in terms of development potential.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.1
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• pp.80-88
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• 2018

The function of a vehicle holding device (VHD) is to securely hold a launch vehicle on the launch pad and release the launch vehicle at maximum thrust after engine ignition to allow lift-off of the launch vehicle. During the release of the launch vehicle, to prevent the Ka doing a doing a doing mode, which is the vertical oscillation of the entire liquid propellant, the release of the launch vehicle should be gradual. In this study, for the gradual release of a launch vehicle, a hydraulic system comprising an accumulator and pyro valve to operate a hydraulic cylinder and control the speed of the cylinder with an orifice is introduced. Through a test, the influence of design variables on the cylinder speed is analyzed. Based on this, the design values of the hydraulic cylinder are determined. Through this study, the engineering basis for developing a VHD releasing a launch vehicle at maximum thrust is provided.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.5
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• pp.132-140
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• 2018

To lunch the Korea Space Launch Vehicle-II(KSLV-II), a second launch complex will be built at the Naro Space Center, and a Kerosene Filling System (KFS) will be installed. KFS of KSLV-II launch complex system is being designed based on Naro Launch Complex. But this must supply fuel to fuel tanks of the vehicle with only a supply pump because KSLV-II is a 3-stage launch vehicle unlike Naro Launch Vehicle or Test Launch Vehicle (TLV). A sudden rise of pump output pressure is recognized during fuel filling scenario selection process. This occurs because return flow can not actively deal with much flow change using the orifice-type flow-control method. To solve this problem, it is verified that fuel can be stably supplied by installing an accumulator, designed for appropriate adjustment of filling-mode change sequence via flow analysis of various cases.

• Journal of the Korean Society of Propulsion Engineers
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• v.26 no.3
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• pp.32-42
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• 2022

The strategy to develop a launch vehicle family by bundling multiple rocket engines of a single type has been proven by SpaceX and their reusable fleet comprised of Falcon 9 and Falcon Heavy. In this study, we revisit a potential launch vehicle family out of a 35 tonf-class methalox staged combustion cycle engine and evaluate their utility and performance in various space missions. For example, a Korean version of Falcon 9 can deliver 4.7 tons of payload into 500 km SSO in an expendable mode while the payload is reduced to 2.16 tons in a sea-landing reusable mode. A Korean version of Falcon Heavy can deliver 4.4 tons into GTO when launched from the Naro Space Center, indicating that this common booster core configuration can handle Cheollian 2 albeit the high inclination. Once developed, the same methaloax engine can power the first-stage of smallsat launch vehicles and air launch vehicles.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.6
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• pp.72-86
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• 2019

SpaceX is currently leading the global launch market with the successful launch and recovery of Falcon 9 v1.2 Block 5. SpaceX developed Merlin engine, a kerosene gas generator engine, and continuously upgraded the engine from Falcon 1 to Falcon Heavy to increase payload weight. SpaceX suffered a lot of failures early on, but with the help of NASA, it was possible to overcome many crises and develop vehicles. In addition, it successfully developed reusable vehicles, which drastically reduced operating costs. Subsequent launch vehicles in Korea also need to be developed with reference to SpaceX's development strategy.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.5
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• pp.107-114
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• 2018

Korea Space Launch Vehicle (KSLV)-I flight test data and the modified 1-dimensional steady state modeling data from the critical design results of the KSLV-II liquid oxygen filling system operation are compared to validate the reliability of critical design modeling. A comparison of major flow rates and pressure values between test data and calculation results are conducted. The relative errors relative to maximum total flow rate for each cooling, filling, and replenishment mode are determined within 6.7%. Calculated pressure values at the outlet of the pump and the inlet of flow control valves are within 5.1%. The pressure at the inlet of the launch vehicle for each operation mode are within the measured pressure range.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.1
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• pp.44-50
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• 2017

Vehicle Holding Device(VHD) has a role that holding the launch vehicle on its launch pad until the engine therust reaches a steady condition. The analytical study of shape parameters and dynamic characteristics of hydraulic cylinders is carried out. The contraction of cylinder is considered as the major factor of releasing mechanism. Through the analysis, the decreasing of cylinder slit size and increasing initial charging pressure increase the contraction force. Through the transient analysis, cylinder load, displacement and inner pressure distribution are confirmed. The cylinder contraction force is converged to the cylinder external force when the cylinder starts to move. Also, the pressure distribution in the hydraulic cylinder is constant.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.6
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• pp.75-81
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• 2014

The flame deflector should be constructed to minimize the induced environmental effects on the launch vehicle and to minimize the exhaust impingement effects on the launch complex structures during the lift-off operation. Therefore, it should be designed to avoid recirculation and reverse flow of rocket exhaust plumes. The circumstance around launch complex and characteristics of launch vehicle should be taken into consideration for the flame deflector design. In this paper, we designed the flame deflector reflecting KSLV-II 1st engine characteristics and analyzed the effect of exhaust plumes related to change geometry by means of computational flow analysis.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.3
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• pp.76-83
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• 2017

Korea Aerospace Research Institute(KARI) has been developing a new launch vehicle Korea Space Launch Vehicle-II(KSLV-II) with their own technology. Thus, it is required a new launch complex that corresponds to a new propulsion system of launch vehicle. Because widely changing of KSLV-II comparing with KSLV-I such as thrust of engine system, composition of vehicle staging, pneumo-hydraulic scheme of propulsion system, it is important to establishing appropriate ground support equipments for fuel(kerosene) filling. In this critical design process, specific supply line and specification of components are designed and the concept of kerosene filling is determined based on results of preliminary design. Also, plans of supply operation and prerequisite are established and operation algorithms are formed.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.4
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• pp.50-58
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• 2016

Korean Space Launch Vehicle (KSLV-II) Propellant Supply System charges liquid oxygen and kerosene to each propellant tank for the stages. To charge the launch vehicle propellant tank safety, the propellant charge flow rates and scenarios should be defined. First, the Propellant Supply System was modeled with 1D flow analysis program. The control valve capacity and orifice size were calculated by performing the 1D steady state simulation. Second, the 1D transient simulation was performed by using the steady state simulation results. As propellants were being charged at the each tank, the increased tank liquid level decreases the charge flow rate. Consequently, the proposed supply system satisfies the required design charging conditions.