• Journal of KSNVE
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• v.10 no.2
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• pp.229-239
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• 2000

To reduce the drag rise on the advancing helicopter rotor blade tips, the tip of the blade is modified to have sweep, anhedral and pretwist. The equations of motion of rotor blade with these tip angles were derived using Hamilton principle, programmed using FORTRAN and named as ARMDAS(Advanced Rotorcraft Multidisplinary Design and Analysis System). Rotating frequency analysis of rotor blades with swept tipe was performed that is necessary in conceptual and preliminary design phases of the helicopter design. Vibration analysis of non-rotating blades was also accomplished and compared with MSC/NASTRAN resutls for the basis of comparison with the vibration test data. The rotating frequency analysis of blades with an actual rotor blade data was also performed to verify coded program and to check the possibility of a resonance of an actual rotor blade at the specific rotating speed.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.208-212
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• 2003

An airborne radar is an essential aviation electronic system of the helicopter to perform various missions in all-weather environments. This paper presents the conceptual design results of the multi-mode pulsed Doppler radar system testbed model for helicopter. Due to the inherent flight nature of the hovering vehicle which is flying in low-altitude and low speed, as well as rapid maneuvering, the moving clutters from the platform should be suppressed by using a special MTD (Moving Target Detector) processing. For the multi-mode radar system model design, the flight parameters of the moving helicopter platform were assumed: altitude of 3 Km, average cruising velocity of 150knots. The multi-mode operation capability was applied such as short-range, medium-range, and long-range depending on the mission of the vehicle. The nominal detection ranges is 30 Km for the testbed experimental model, but can be expanded up to 75 Km for the long range weather mode. The detection probability of each mode is also compared in terms of the signal-to noise ratio of each mode, and the designed radar system specifications ate provided as a design results.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.7
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• pp.685-692
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• 2009

This paper dealt with the development of the Framework for Multidisciplinary Design Optimization for the rotorcraft design concept and the building process of KHP(Korea Helicopter Project) - SDM(Simulation Data Management) system to manage various analysis data, which are used in the rotorcraft development phase. KHP-SDM RMDO(Rotorcraft Multidisciplinary Design Optimization) framework, which applied optimization modules of KHP-SDM and integrated the developed Multidisciplinary analysis modules, was constructed in the KHP-SDM. The results of the rotorcraft conceptual design using KHP-SDM RMDO showed that the framework was evaluated to be successfully constructed.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.9
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• pp.9-15
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• 2005

This paper describes the test carried out on an experimental study of fuselage drag and stability characteristics of a helicopter configuration and the test techniques developed for the testing and the lessons learned in the Agency for Defense Development Low Speed Wind Tunnel(ADD-LSWT). The main objective of this test is to determine the drag and stability characteristics of helicopter configurations according to the various configuration changes. The fuselage model with a highly modular structure is a representation of 1:8 scale of the external contour of the conceptual design helicopter configuration with rotating main rotor hub including blade stubs capable of rotating up to 500 rpm. The test results are compared with the available similar data and fair to good agreement is obtained.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.6
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• pp.452-463
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• 2018

Tip-jet gyroplane is a type of compound helicopter that employs the tip-jet system to rotate the rotor by a reaction force from the gas jetted at the rotor tips in hovering. In forward flight, tip-jet gyroplane converts into a form of a gyroplane. Therefore, it is necessary to develop a new conceptual design method to consider three flight modes: tip-jet mode, gyroplane mode, and transient mode. This study developed the numerical code of conceptual design methodology that can consider three flight modes. The developed code was validated against the available experiment data. Based on the developed code, initial sizing of tip-jet gyroplane was performed for two mission profiles including high speed forward flight of 150knots with a mission range of 300km or 400km. Subsequently, the configuration and performance of the 3,000lb tip-jet gyroplane were analyzed.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.1
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• pp.33-38
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• 2005

Forcing at the rotor blade passing frequencies is responsible for the majority of vibration related problems on helicopters. Blade passing frequencies of helicopters are generally in the range 10~30 Hz and the interest modes of the helicopters also exist in the range. By the way, the installation of a heavy sensor at the front extremities of an imported helicopter may change the modal characteristics of the airframe and results in the resonance with rotor passing frequencies. To avoid too large a change in the dynamics of the overall airframe, we determined how to install a heavy sensor through conceptual approach and finite element analysis. The results of a ground vibration test for airframe with sensor mount system clearly demonstrate that the installation design is acceptable dynamically.

• Journal of Aerospace System Engineering
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• v.2 no.3
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• pp.29-32
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• 2008

The overview of KUH design and development process is presented according to Buede's systems and development "vee" model. The system decomposition and integration activities exemplify KUH specification tree, design maturity and analysis according to design stage(conceptual, preliminary, and detail design), scheduled work breakdown structure, qualification test, ground test, and flight test. This process can be applied to the development of a new aircraft.

• Journal of the Korean Society of Propulsion Engineers
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• v.7 no.4
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• pp.19-26
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• 2003

In this paper, the result of the conceptual study of a tipjet driven propulsion system is presented. The concept of a tipjet driven propulsion system is to employ tipjet as power source to drive a rotor Because the vehicle is supposed to takeoff and land vertically, a rotor system, which has tipjet nozzles, is adopted to fly like a helicopter. Exhaust gas, which is generated by an engine, Passes through an internal duct system and divided into four blade ducts. The design code is consists of two parts, engine model and internal duct model. Inside a rotating duct, compressible flow is affected by two additional force terms, centrifugal force and coriolis force and they govern the performance in rotary mode, The intention of this paper is to address the issues associated with sizing and optimizing configurations of a tipjet driven propulsion system especially in rotary wing mode.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.12
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• pp.997-1004
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• 2020

A synchropter is a type of rotorcraft in which a pair of blades inclined with each other rotates in synchronization. Removing the tail rotor enables an efficient and compact configuration similar to a coaxial-rotor helicopter. This paper describes the design and flight test results of a small synchropter to examine the suitability of a drone system for the army. The synchropter in this paper is a small vehicle with a rotor diameter of 1.4m and a weight of 7kg and was assembled based on commercial parts to examine flight characteristics effectively. The flight control system adopted Pixhawk, which is designed based on an open-architecture. The model-based design technique is applied to develop the control law of the synchropter and a new firmware embedded on the Pixhawk. Through qualitative flight tests, we analyzed the flight characteristics. As a result of the analysis, we confirmed the possibility of application as a drone system of the synchropter.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.1
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• pp.75-84
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• 2021

The authors had presented two previous papers[1,2] on Helicopter/Rotorcraft develoment in Europe and US. Meanwhile, the next generation rotorcrafts, currently under development in US and Europe, have new configurations (tilt-rotor, coaxial, compound) of rotor-type vertical takeoff/landing rotorcrafts to overcome the disadvantages of traditional helicopters. For developing these new types of rotorcrafts, the upgraded conceptual design/comprehensive programs are required. In US and Europe, they are already developing new program tools with their technologies and database obtained during more than last half centuries. For us, many academia, research institutes and industrial engineers have experienced and developed core technologies on rotorcrafts (aerodynamics, structural analysis, flight dynamics, and noise analysis etc.) comparable to US and Europe during last couple of decades of developing helicopters and various configurations of rotorcrafts. In this paper, the pros and cons of conceptual design/comprehensive tools currently used in US and Europe have been summarized. Furthermore, the possibilities and problems to develope our own design and analysis tools have been studied.