• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.12
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• pp.997-1010
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• 2021

This study collected and analyzed flight data of SpaceX's Falcon 9 launch vehicle. All missions were classified by orbital types, such as Polar, SSO, ISS, LEO and GTO missions. In characteristic maneuvers of main engine cutoff, boostback, reentry and landing burn at each stage of 1st stage launch vehicle, changes of the physical parameters like speed, altitude, dynamic pressure and acceleration were investigated. The guidelines derived from detailed maneuver analysis were suggested, which can be used as design and evaluation references for developing reusable launch vehicle.

• Aerospace Engineering and Technology
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• v.7 no.1
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• pp.229-235
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• 2008

The ground flight termination system(GFTS) could be used for the termination of launch vehicle in flight motion when the launch vehicle deviates from the designated route due to the system malfunction or failure as well as the launch vehicle can't be tracked by the ground tracking system. This paper introduces the basic concept and design of the ground flight termination system to be used for KSLV launch mission in NARO space center. In order to design the optimal ground flight termination system for KSLV launch application, the operational concept reflected on the flight trajectory and system characteristics of KSLV launch vehicle should be considered. Moreover the RF link budget analysis, and the analysis for system availability and reliability are done. Based on the analysis above, the each subsystem of ground flight termination to transmit the termination signal in stable is designed for KSLV launch mission.

• Journal of Advanced Navigation Technology
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• v.22 no.1
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• pp.13-19
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• 2018

In this paper, we classified a flight pattern of unmanned aerial vehicle(UAV) which will be operating in UTM system and analyzed its flight pattern by purpose of use. Flight patterns of UAV are sorted into three patterns which are circling, monitoring and delivery. We considered four cases of industry areas using UAV which are agriculture, infrastructure monitoring, public safety & security(p.s.s) and delivery. It is necessary to build a simulation model as a verification tool for applying the flight pattern according to the use of UAV to the real UTM system. Therefore, we propose the simulation model of UAV with updating states over time. We applied simulation to UAV monitoring flight pattern, and confirmed that the flight was done by the given input data. The simulation model will be used in the future to verify that the UAV has various flight patterns and can operate safely and efficiently for the intended use.

• International Journal of Aeronautical and Space Sciences
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• v.18 no.3
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• pp.565-573
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• 2017

This paper presents a multistage in-flight alignment (MIFA) method for a strapdown inertial navigation system (SDINS) suitable for moving vehicles with no initial attitude references. A SDINS mounted on a moving vehicle frequently loses attitude information for many reasons, and it makes solving navigation equations impossible because the true motion is coupled with an undefined vehicle attitude. To determine the attitude in such a situation, MIFA consists of three stages: a coarse horizontal attitude, coarse heading, and fine attitude with adaptive Kalman navigation filter (AKNF) in order. In the coarse horizontal alignment, the pitch and roll are coarsely estimated from the second order damping loop with an input of acceleration differences between the SDINS and GPS. To enhance estimation accuracy, the acceleration is smoothed by a scalar filter to reflect the true dynamics of a vehicle, and the effects of the scalar filter gains are analyzed. Then the coarse heading is determined from the GPS tracking angle and yaw increment of the SDINS. The attitude from these two stages is fed back to the initial values of the AKNF. To reduce the estimated bias errors of inertial sensors, special emphasis is given to the timing synchronization effects for the measurement of AKNF. With various real flight tests using an UH60 helicopter, it is proved that MIFA provides a dramatic position error improvement compared to the conventional gyro compass alignment.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.1
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• pp.1-6
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• 2015

This paper investigates the longitudinal flight dynamics and stability of flapping-wing micro air vehicles. Periodic external forces and moments due to the flapping motion characterize the dynamics of this system as NLTP (Non Linear Time Periodic). However, the averaging theorem can be applied to an NLTP system to obtain an NLTI (Non Linear Time Invariant) system which allows us to use a standard eigen value analysis to assess the stability of the system with linearization around a reference point. In this paper, we investigate the dynamics and stability of a hawkmoth-scale flapping-wing air vehicle by establishing an LTI (Linear Time Invariant) system model around a hovering condition. Also, a direct time integration of full nonlinear equations of motion of the flapping-wing micro air vehicle is conducted to see how the longitudinal flight dynamics appear in the time domain beyond the reference point, i.e. hovering condition. In the study, the flapping-wing air vehicle exhibited three distinct dynamic modes of motion in the longitudinal plane of motion: two stable subsidence modes and one unstable oscillatory mode. The unstable oscillatory mode is found to be a combination of a pitching velocity state and a forward/backward velocity state.

• Journal of Electrical Engineering and Technology
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• v.7 no.1
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• pp.132-140
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• 2012

A non-conservative robust Kalman filter (NCRKF) is applied to flight data to identify the aerodynamic derivatives of an unmanned autonomous vehicle (UAV). The NCRKF is formulated using UAV lateral motion data and then compared with results from the conventional Kalman filter (KF) and the recursive least square (RLS) method. A superior performance for the NCRKF is demonstrated by simulation and real flight data. The NCRKF is especially effective in large uncertainties in vehicle modeling and in measuring flight data. Thus, it is expected to be useful in missile and aircraft parameter identification.

• Journal of Aerospace System Engineering
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• v.3 no.4
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• pp.35-40
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• 2009

The first purpose of this study is to develop a GCS(Ground Control System) by using RF(Radio Frequency) wireless communication equipments for UAV(Unmanned Aerial Vehicle). The second goal is to develop an antenna tracking system operating automatically. UAV receives flight data from a RF wireless system. So the role of antenna tracking system is very important to keep good communication state between UAV and GCS. GCS can check flight data and display a aviation state of UAV in real-time. The flight data displayed in real-time by GCS include the latitude, longitude, altitude, speed and so on. Experiments that measure a communication range and reliability are needed to develop a RF wireless communication system.

• Journal of Aerospace System Engineering
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• v.11 no.1
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• pp.14-21
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• 2017

A Linear parameterized Sigma-Pi neural network (SPNN) is applied to a tilt-duct unmanned aerial vehicle (UAV) which has a very large longitudinal stability ($C_{L{\alpha}}$). It is uncontrollable by a proportional, integral, derivative (PID) controller due to heavy stability. It is shown that the combined inner loop and outer loop of SPNN controllers could overcome the sluggish longitudinal dynamics using a method of dynamic inversion and pseudo-control to compensate for reference model error. The simulation results of the way point guidance are presented to evaluate the performance of SPNN in comparison to a PID controller.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.573-576
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• 2004

KARI is achieving the KSLV program according to National Space Technology Development Program. In this paper, the authors are intended to introduce the Integrated Power Plant (abb. IPP) test facility which will be constructed for the variety of tests on KSLV program. IPP test facility refers to comprehensive testing equipment for liquid rocket launch vehicle. Using this facility, KARl can verify the adaptiveness of parts and subsystems for launch vehicle and finally can qualify the system characteristics of launch vehicle doing kinds of test including hot firing test. Using this facility, KARI can simulate the vehicle launching circumstances and it make to predict the performance of launch vehicle when its flight test.

• Journal of Advanced Navigation Technology
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• v.9 no.2
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• pp.185-192
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• 2005

The aim of this paper is to analyze handling qualities of tiltrotor aircraft(TR-S4) in helicopter flight mode including hovering and forward flight. Analysis of handling qualities is composed of aircraft response to control inputs that effect on stability and controllability. In short term response analysis, bandwidth is the critical parameter for small amplitude motions since it relates to the ability of a pilot to crisply start and stop maneuver. The handling qualities of TR-S4 in helicopter mode are analyzed with a SAS and an attitude controller and are satisfied level 1 in almost criteria with simulation of TR-S4 6-DOF nonlinear model.