• Aerospace Engineering and Technology
• /
• v.11 no.2
• /
• pp.208-215
• /
• 2012

The acoustic noise around a launch pad by launches of space launch vehicles was analyzed. The magnitudes of sound noise at some points near launch pad were predicted by locating the sound source at the exhaust jet plume of the rocket engine and considering several factors such as the directivity of the sound propagation and atmospheric attenuation. Specifically, the launch noise of Korea Space Launch Vehicle-I (KSLV-I) was estimated, and was compared to the actual measurement results. The analysis results proved to be heavily affected by the characteristics of directivity of sound propagation and the analysis showed good agreements with the measurements when the directivity of the sound was appropriately adjusted.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2014.04a
• /
• pp.207-210
• /
• 2014

This paper is concerned with the prediction of lift-off acoustic loads for a launch vehicle. Intense acoustic load is generated when a launch vehicle is lifted off, and it can induce vibrations of a launch vehicle which cause damage or malfunction of a launch vehicle and a satellite. Lift-off acoustic loads of NARO are predicted by the modified Eldred's second method and the result is compared with the measured data in flight test. The prediction shows similar peak and shape of spectrum to the test data, but some discrepancy can be observed due to the predicted margin. In order to reduce such discrepancy, the sound pressure levels with four source distribution assumptions are calculated. Also, the surface diffraction effects are considered in the predict ion of lift-off acoustic loads, and the predicted result is more similar to the test data.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2000.06a
• /
• pp.1252-1258
• /
• 2000

Koreasat-3 was successfully launched by an Ariane IV launch vehicle on September 5, 1999. Although the primary purpose of the satellite is to replace Koreasat-l, it also can extend its communication service coverage over the Asia-Pacific region. A spacecraft is subjected to severe dynamic loads during launch period. To verify the safety of spacecraft under the launch environment, dynamic tests should be performed such as sine sweep, acoustic and separation shock tests. This paper presents the launch environment test results of Koreasat-3. A total of 188 acceleration responses was measured and compared with the design requirements of components and spacecraft. Dynamic characteristic change was also investigated by comparing between low-level pre/post vibration results. From the review of test results, it is concluded that Koreasat-3 was designed and manufactured with the margin of safety enough to survive the launch loads of Ariane IV.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2004.11a
• /
• pp.747-750
• /
• 2004

After launching, spacecraft is exposed to extreme environments. So spacecraft should be tested after design/manufacture to verify whether components can be operated functionally. Acceleration transferred from launch vehicle to spacecraft produces quasi-static load, sine vibration and random vibration. Random vibration is also induced by acoustic vibrations transferred by surface of spacecraft. And shock vibration is produced when spacecraft is separated from launch vehicle. To verify operation of spacecraft under these launch environments, separation shock test, sine vibration test, acoustic vibration test and random vibration test should be performed. This paper describes these launch environment test requirements.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2000.06a
• /
• pp.1234-1239
• /
• 2000

KOMPSAT-1(Korea Multi-Purpose Satellite), which opened the space era in Korean peninsula, was developed from 1994 and launched successfully in December of 1999 at VAFB, USA. This paper presents a launch environment test of KOMPSAT and a short description of environment test facilities at Korea Aerospace Research Institute as well. The launch environment tests of KOMPSAT-1 satellite, such as vibration, acoustic, pyro-shock and mass properties measurement test, were performed during its system integration and test period. The participating engineers concluded that KOMPSAT-1 satellite would withstand environment during its launch period.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2006.05a
• /
• pp.258-261
• /
• 2006

The structure of small launch vehicle can be divided into engine section and payload section. This paper introduces modal test of the payload section of small launch vehicle which is composed to satellite, PLA (Payload Adapter), VEB (Vehicle Equipment Bay), KMS (Kick Motor Support) and KM (Kick Motor). From this test, dynamic properties of the 2nd stage structure of small launch vehicle can be obtained. In this test, to simulate free-free boundary condition, test object was hung by 4 bungee cords and excited by using impact hammer Modal test data are analyzed by using TDAS(Test Data Analysis Software). As the result, modal parameters and mode shapes below 100Hz of the 2nd stage of small launch vehicle were identified.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2011.10a
• /
• pp.163-168
• /
• 2011

Noise map is drawn up under launch environment through analyzing jet noise of guided weapon in this research. This has an important significance in terms of having an opportunity to look at influence of noise which is caused by guided weapon in the surrounding environment. In this paper, the magnitude of jet noise that was measured by using microphone and the result of numerical analysis that was gained by using ENPro which is environment noise prediction program are shown. At this point estimation of noise source was based on ISO 9613. Finally noise map derived from results mentioned above will become useful material when setting safety guide for protecting hearing loss of operator of weapon system in the future.

• The Journal of the Acoustical Society of Korea
• /
• v.39 no.4
• /
• pp.322-330
• /
• 2020

This study investigates the far-field noise from three Falcon 9 vehicle launches from Vandenberg Air Force Base, CA, USA, as measured from the same location within the nearby community of Lompoc. The overall sound pressure levels for the three launches are shown to be similar, but some differences in the early launch period are thought to be weather-related. The peak directivity angle in overall level is approximately 65 deg, which is consistent with horizontally-fired, static rocket data. For the third launch, waveforms and spectra are analyzed for different events during the launch sequence. The measured spectral bandwidth decreases with time, but spectral levels remain above the ambient noise throughout the main-engine firing. Additionally, late-launch phenomena observed in the data appear to be correlated with main-engine cutoff and second-stage engine start.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.24 no.7
• /
• pp.517-524
• /
• 2014

Micro-vibration induced by on-board equipments such as fly-wheel and cryogenic cooler with mechanical moving parts affects the image quality of high-resolution observation satellite. Micro-vibration isolation system has been widely used for enhancing the pointing performance of observation satellites. In general, the micro-vibration isolation system requires a launch locking mechanism additionally to guarantee the structural safety of mission payloads supported by the isolation system with low stiffness under launch environment. In this study, we propose a passive launch and on-orbit vibration isolation system using shape memory alloy mesh washers for the micro-vibration isolation of spaceborne compressor, which does not require the additional launch locking mechanism. The basic characteristics of the isolator were measured in static and free vibration tests of the isolator, and a simple equivalent model of the isolator was proposed. The effectiveness of the isolator design in a launch environment was demonstrated through sine vibration, random vibration and shock tests.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.25 no.8
• /
• pp.539-545
• /
• 2015

Intense acoustic load is generated when a launch vehicle lifts off, causing the damaging vibrations at the launch vehicle or satellite within the fairing. This paper is concerned with the prediction of lift-off acoustic loads for a launch vehicle. As a test example, the lift-off acoustic load on the Korean launch vehicle, NARO, is predicted by the existing calculation tool, the modified Eldred's second method. Although the acoustic sources, assumed as point sources, are to be located along the center line of the exhaust plume when using the Eldred's prediction method, the exact location of the deflected center line of exhaust gas flow is not usually known. To search for the most appropriate source positions, six models of source line distribution are suggested and the acoustic load prediction results from these models are compared with the actual measurements. It is found that the predicted sound pressure spectrum of the Naro is the most similar to the measured data when the centerline of the turbulent kinetic energy contour is used as the source line.