• Journal of Aerospace System Engineering
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• v.13 no.2
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• pp.1-9
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• 2019

This paper elaborates on the directional axis guidance and control algorithm used in mission flight for high altitude long endurance UAV. First, the directional axis control algorithm is designed to modify the control variable such that a strong headwind prevents the UAV from moving forward. Similarly, the guidance algorithm is designed to operate the respective algorithms for Fly-over, Fly-by, and Hold for way-point flight. The design outcomes of each guidance and control algorithm were confirmed through nonlinear simulation of high altitude long endurance UAV. Finally, the penultimate purpose of this study was to perform an actual mission flight based on the design results. Consequently, flight tests were used to establish the flight controllability of the designed guidance and control algorithm.

• Journal of the Korea Institute of Military Science and Technology
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• v.26 no.1
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• pp.83-90
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• 2023

The external store fitted to the aircraft may affect the flight characteristics and flight safety of the aircraft, which requires the analyses and testing on it. The purpose of this study is to identify and analyze types of failures that can affect the flight safety of aircraft due to the installation of external stores, and to check the flight safety of aircraft through dropping tests of the external stores. After identifying the types of failures that could affect the flight safety of the aircraft, the criticality was calculated to analyze the effect on the flight safety of the aircraft. Four types of failures were selected: unintentional dropping, failure of dropping, unintentional main wing deployment, and release of tail wing restraint of the external store, which are considered to affect the flight safety of the aircraft due to the operation of the external store. As a result of the aircraft's flight safety analysis on the failure types, the criticality requirements were met. Based on this, after obtaining the airworthiness certification, the drop test was successfully performed to confirm the flight safety of the aircraft by mounting an external store on the aircraft. However, in addition to the four hazards carried out in this study, the real external stores of the military aircraft may have various factors affecting the flight safety of the aircraft, so further research will be needed.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.3
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• pp.264-273
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• 2010

In this work, autonomous formation flight tests of multiple UAVs are experimentally studied. After a guidance and control system for a UAV is designed and tested, PID formation controller for follower UAV is tested using longitudinal and lateral distance feedback. It is shown that more stable and efficient formation guidance system is obtained by using position and attitude of the leader aircraft, which is exploited to calculate virtual waypoint for follower. In order to improve transient response during turn, part of roll command of the leader is added to the guidance command. Finally, autonomous formation flight test results of 3 UAVs are shown by using the best guidance algorithm suggested.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.9
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• pp.104-112
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• 2005

This paper presents the technique to develop an operational flight program(OFP) of avionic system computer(ASC) which integrates the avionics control, navigation and fire control and provides informations for flight, navigation and weapon aiming missions. For the development of the OFP of ASC, two i960KB chips are used as central processing units board and standard computer interface library(SCIL) which is built in house is used. The Irvine compiler corporation(ICC) integrated development environment(IDE) and the programming language Ada95 are used for the OFP development. We designed the OFP to a computer software configuration item(CSCI) which consists of to three parts for independency of software modules. The OFP has been verified through a series of flight tests. The relevant tests also have been rigorously conducted on the OFP such as software integrated test, and ground functional test.

• Advances in aircraft and spacecraft science
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• v.6 no.2
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• pp.117-144
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• 2019

High Altitude and Long Endurance (HALE) aircraft are capable of providing intelligence, surveillance and reconnaissance (ISR) capabilities over vast geographic areas when equipped with advanced sensor packages. As their use becomes more widespread, the demand for additional range, endurance and payload capability will increase and designers are exploring non-conventional configurations to meet the increasing demands. One such configuration is the joined-wing concept. A joined-wing aircraft is one that typically connects a front and aft wings in a diamond shaped planform. One such example is the Boeing SensorCraft configuration. While the joined-wing configuration offers potential benefits regarding aerodynamic efficiency, structural weight, and sensing capabilities, structural design requires careful consideration of elastic buckling resulting from the aft wing supporting, in compression, part of the forward wing structural loading. It has been shown already that this is a nonlinear phenomenon, involving geometric nonlinearities and follower forces that tend to flatten the entire configuration, leading to structural overload due to the loss of the aft wing's ability to support the forward wing load. Severe gusts are likely to be the critical design condition, with flight control system interaction in the form of Gust Load Alleviation (GLA) playing a key role in minimizing the structural loads. The University of Victoria Center for Aerospace Research (UVic-CfAR) has built a 3-meter span scaled and flexible wing UAV based on the Boeing SensorCraft design. The goal is to validate the nonlinear structural behavior in flight. The main objective of this research work is to perform Ground Vibration Tests (GVT) to characterize the dynamic properties of the scaled flight vehicle. Results from the experimental tests are used to characterize the modal dynamics of the aircraft, and to validate the numerical models. The GVT results are an important step towards a safe flight test program.

• Journal of the Korea Institute of Military Science and Technology
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• v.4 no.2
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• pp.227-232
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• 2001

IPresented is a small and handy remotely piloted vehicle(RPV) that can be used for military and non-military surveillance operations. The RPV is equipped with an on-board high resolution color camera to transmit the analog video images and on-board electronics to provide real-time flight information to the pilot, thereby enabling him/her to remotely pilot within the range of 5 km radius. This paper describes the RPV system including its design, manufacturing and flight test results which manifest the stability of on-board mission and flight equipment as well as the remote piloting capability. A future plan for necessary improvements identified from the flight tests are also discussed.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.762-767
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• 2008

Estimated values for maximum lift coefficients of a light airplane, ChanGong-91, derived from an analytical method using a test database, a computational fluid dynamic method, a wind tunnel test, and a flight test are compared. The DATCOM method and VSAERO code are applied as the analytical method and the computational fluid dynamic method, respectively, in order to estimate the maximum lift coefficients of a light airplane. The wind tunnel test is conducted using a 1/14.5 scaled model installed in a closed circuit type wind tunnel. For the flight test approach, the wings-level power-off stall tests are performed to obtain the maximum lift coefficients. As a point of reference for the flight test results of the maximum lift coefficients, the differences of both estimates derived from the DATCOM method and the wind tunnel test data are smaller than those derived from VSAERO.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.8
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• pp.105-110
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• 2005

Analysis technique of flight compatibility test results using instrumented pod for external store is studied. Raw data of sensors and MIL-STD-1553B acquired from instrumented pod are analyzed separately. Besides, tuning and synchronization of sensor data enable the analysis of those two type of data simultaneously. Evaluation of analysis result shows that the analyzed data represent maneuvers of the aircraft successfully and agree the values of the real flight tests.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1993-1998
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• 2004

The present study was carried out to develop highly efficient RC ornithopter 'Songgolmae' powered by motor and battery. Designed electric ornithopter weighs 277 grams and has 3 channels radio control. 1t runs on an electric motor by a lithium polymer battery and has a gear ratio of about $75{\sim}95$ to 1 to flap its 88 cm wingspan. The aerodynamic performance of the ornithopter, applied to a flapping motion only, was validated by flight tests. Flight times have exceeded 23 minutes until the battery was used up. The flight test results indicate that the ornithopter developed here has sufficient thrust to propel itself in a forward flight. From the economical point of view and the handling of the RC ornithopter, it can be said that the developed robot ornithopter is an effective RC ornithopter. This radio controlled ornithopter flies its way high into the sky just like a real bird flies.

• Journal of Biosystems Engineering
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• v.36 no.6
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• pp.476-483
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• 2011

The aerial application using an unmanned helicopter has been already utilized and an attitude controller would be developed to enhance the operational convenience and safety of the operator. For a preliminary study of designing flight controller, a state space model for an RC helicopter would be identified. Frequency sweep flight tests were performed and time history data were acquired in the previous study. In this study, frequency response of the flight test data of a small unmanned helicopter was analyzed by using the CIFER software. The time history flight data consisted of three replications each for collective pitch, aileron, elevator and rudder sweep inputs. A total of 36 frequency responses were obtained for the four control stick inputs and nine outputs including linear velocities and accelerations and angular velocities in 3-axis. The results showed coherence values higher than 0.6 for every primary control inputs and corresponding on-axis outputs for the frequency range from 0.07 to 4 Hz. Also the analysis of conditioned frequency response showed its effectiveness in evaluating cross coupling effects. Based on the results, the dynamic characteristics of the model helicopter can further be analyzed in terms of transfer functions and the undamped natural frequency and damping ratio of each critical mode.