A study on structural safety of mechanical ground support equipment during the launch operation of a Korea small launch vehicle (KSLV-1)

Abstract

The responsibility of the mechanical ground support equipment (MGSE) during the launch operation of a space rocket is to provide mechanical maneuvering for the rocket (e.g., transporting, erecting to a vertical position, lowering to a horizontal position) and an automatic mating/de-mating of ground propellant filling lines for the LV. Those MGSE should have structurally enough stiffness and strength to protect and avoid a resonance with the LV during launch operation. This paper introduces the study of structural safety of the MGSE under the structural loading environment during the launch operation of a Korean small launch vehicle (KSLV-1). For this study, computer-aided analysis was performed. To verify FEM model, a static loading test for MGSE in horizontal position was performed. Then displacement data acquired from static loading test were compared with the result of computational analysis. With the FEM model verified above, to check the possibility of resonance between the LV and the MGSE, the first step was to perform normal mode analysis to identify the natural frequencies of the LV and the MGSE. Then, the normal mode analysis for the integrated LV and -MGSE assembly was performed. By comparing the results of each normal mode analysis, the possibility of resonance was analyzed. To check the structural safety under the loading environments of wind and gravity, the stress analysis of the MGSE in vertical position which is most critical loading case was performed. Results show that there is no possibility of resonance between LV and MGSE and the calculated margin of safety is at least above 7. Through several qualification tests of MGSE and three actual flight tests of the KSLV -1, all MGSE worked properly and no resonance occurred between the LV and MGSE. Also, there was no mechanical damage found on the MGSE. The procedure adapted for the development of MGSE for KSLV-1 can be used on the development MGSE for future project.