External stores on low-speed rotorcraft are subjected to various external forces depending on the aircraft's operating conditions. While there are different types of external forces, this paper focuses on flight loads as defined by US defense specifications. Flight loads consist of static and dynamic loads. Static loads on aircraft external stores include inertial loads resulting from aircraft maneuvers and aerodynamic loads caused by the downward flow of the main wing. To define the inertial load, the inertial load factor on external stores was calculated, while the minimum analysis case for aerodynamic load was derived from trim analysis of rotorcraft blades. The critical design load diagram was developed by combining these factors, and ANSYS was utilized to analyze the structural robustness under static loads. Based on the characteristics of the main wing, a finite element analysis was conducted using a vibration profile tailored to the actual operating environment and an impact profile suitable for the impact conditions. Structural robustness was further assessed through actual tests. This analysis provides essential data for airworthiness certification, allowing for the safe installation of external stores on low-speed rotorcraft.
A pod mounted on an aircraft external must be installed on an aircraft after its structural safety is verified under flight conditions. This paper presents methods of flight load and test load generation. Evaluation of test result data and standards for failure mode are also presented. First of all, to verify the static structural stability, flight loads for the aircraft maneuvering conditions were calculated. Finite element analysis was then performed with flight loads. As a result of the analysis, structures were verified to have a margin of safety for a given design requirement. In addition, it was confirmed that the launcher tube had enough rigidity to support the missile. Thus, the role of stinger such as longeron and hardback was insignificant. Finally, based on results of tests and analysis, the static structural stability of pod was substantiated and the reliability and effectiveness of the analysis model were obtained. These results and dynamic stability verification results suggest that an optimal design is necessary.
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Calculation of Flight Loads and Structural Robustness Analysis of Aircraft External Stores Considering Low Speed Rotorcraft Installation Ji Hwan Park, Chang Bong Ban, Jong Hwan Kim, Sun Kyu Ahn Journal of the Korean Society for Precision Engineering.2025; 42(8): 613. CrossRef
The main function of aircraft ejection system is that it separates the store from the aircraft. The ejection force is important for the safety of the aircraft when the store is ejected, because the store can be lifted by air flow affected by the aircraft’s speed. If the ejection force is low, the aircraft can be damaged by the floating store. The ejection force of the suspension system should be designed in order to release the store safely. In this study, the ejection force of the pyrotechnic suspension using the cartridge to eject the store was researched. This research was performed, based on the precedent study about the over-center linkage mechanism and the pressure drop by the orifice. The ejection force was calculated, after analyzing mathematical fundamentals about the pressure in the system of the suspension and analyzed through AutoDyn and ADAMS software. Finally, the theoretical results were compared with the ejection test results of the suspension system.
An airborne black box should preserve the recorded data under the extreme environmental conditions such an aircraft crash. Through the recorded information from the black box, the cause of the aircraft crash can be analyzed. This requires the black box to safely protect its memory board inside from the external forces or heat generated by the aircraft crash. This paper is a case study conducted to develop the black box to satisfy the crash survival requirements of ED-112A, the standard of performance to develop the black box, and optimize its weight and size. Through the sequential design, analysis, and test process, the black box successfully demonstrated the optimized design, analysis and test subjected to crash survival requirements of ED-112A. The prototype of the black box was fabricated and tested for the verification of each analysis within the requirements of ED-112A.
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Study on the Design Method of Small Black Box for Aircraft that Satisfies Extreme Environment Requirements Dong-Hun Son, Kwang-Min Kim, Jong-Hak Lee, Gu-Hyun Ryu Transactions of the Korean Society for Noise and Vibration Engineering.2024; 34(4): 385. CrossRef
If fatigue failure occurs during aircraft operation, it can cause catastrophic injuries. So, it is necessary to study fatigue failure at the design stage. Frequency domain fatigue analysis is used to predict fatigue failure. During frequency domain fatigue analysis, results can be calibrated by PSD analysis. In this study, fatigue failure is predicted by the Dirlik method, Lalanne method and Steinberg method. Regarding results, life determined by the Dirlik method, Lalanne method and Steinberg method were 8.737, 8.314, and 7.901 times the standard life, respectively. The Steinberg method is the most conservative but the difference with other methods was approximately 10%. In the cycle histogram, the Dirlik method had more counts than the Lalanne method in lower stress range. However, it does not affect the life of material used in this study. However, if material has a lower fatigue limit or stronger PSD data is used, life difference will occur.
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Analysis of Acoustic Load Fatigue Life of Skin of POD for Aircraft considering Aspect Ratio Wonwoong Lee, Jaemyung Cho, Jongin Bae, Hoonhyuk Park Journal of the Korea Institute of Military Science and Technology.2025; 28(2): 126. CrossRef
A Study of Vibration Analysis of 100 MPa Class Fitting Thread for Mobile Hydrogen Charging Station JUNYEONG KWON, SEUNGJUN OH, JUNGHWAN YOON, JEONGJU CHOI Transactions of the Korean Hydrogen and New Energy Society.2024; 35(1): 83. CrossRef
Very high cycle fatigue on gas metal arc butt-welded AA6061-T6 plates Iksu Kim, Moon G. Lee, Martin Byung-Guk Jun, Jungho Cho, Yongho Jeon Journal of Mechanical Science and Technology.2023; 37(12): 6649. CrossRef
Vibration-Based Fatigue Analysis of Octet-Truss Lattice Infill Blades for Utilization in Turbine Rotors Sajjad Hussain, Wan Aizon W. Ghopa, S. S. K. Singh, Abdul Hadi Azman, Shahrum Abdullah, Zambri Harun, Hawa Hishamuddin Materials.2022; 15(14): 4888. CrossRef
Experimental Verification of Dirlik Fatigue Evaluation in Frequency Domain Using Beam Structure under Random Vibration Eunho Lee, Siyoung Kwak Transaction of the Korean Society of Automotive Engineers.2021; 29(2): 157. CrossRef
Major aerospace developers continue to push for new structural composite applications to reduce the environmental impact of greenhouse gas emissions, improve both aircraft performance and costs. In this study, the parts that carry the load in the regions where mechanical joints are applied, require whole processing to tighten and identify stress concentration points. In addition, failure modes caused by bearing and by-pass loads were set as the main design factors. Optimum sizing was performed through the application of factors taken into account in the buckling failure mode and production using the preliminary design analysis model of the composite wing structure. In the area where the fuselage is joined with the fuselage, bearing and bypass load were considered important design factors.
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