• Title/Summary/Keyword: Flight Modes

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Compositing Modes and Microstructures of $Cu-X(=Al_2O_3,W)_p$ Composite by Centrifugal Spray-Cast Deposition (원심분사주조법에 의한 $Cu-X(=Al_2O_3,W)_p$ 복합재료의 미세조직 및 복합화)

  • Bae, Cha-Hurn;Jeong, Hae-Yong
    • Journal of Korea Foundry Society
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    • v.17 no.5
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    • pp.480-487
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    • 1997
  • Particle reinforced metal matrix composites(MMCs) via a centrifugal spray-cast deposition(CSD) process were fabricated by injecting second phase particles($Al_2O_3$<40${\mu}m$, W<17.3${\mu}m$) into copper melt on the atomizing disc. Compositing modes were investigated by combining microstructures and mathematical modeling between Cu droplets and the reinforced particles injected. The $Cu/W_P$ powders were shown that the W particles penetrate and get embedded in the Cu droplets. It is considered that the W particles composite preferentially in Cu melt on the atomizing disc. On the other hand, the $Al_2O_3$, particles did not penetrate into the Cu droplets on the atomizing disc but get attached in surface of Cu droplets during the flight. It is considered that the compositing may be attained in the flight distance which the relative velocity between Cu droplet and $Al_2O_3$, particle is maximum. The microstructure of the $Cu/W_P$ and the $Cu/(Al_2O_3)_p$ composite preform was strongly influenced by compositing modes of droplets, and after subsequent deposition it was comprised as it is called the dispersed type and the cell type of microstructure, respectively.

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Verification of “dual-master” Duplication Flight Control System using Simulink Virtual Module (Simulink 가상모듈을 이용한 “dual-master” 이중구조 비행제어시스템 검증)

  • Kim, Sung-Su;Kim, Sung-Hwan;Jang, Se-Ah;Choi, Kee-Young;Park, Choon-Bae;Rhee, Ihn-Seok;Ha, Cheol-Keun
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.36 no.9
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    • pp.867-873
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    • 2008
  • Model based virtual Flight Control System construction is essential for Fly-by-Wire Flight Control System verification & validation(V&V) of concurrent engineering base. We researched the concept of dual-architecture system for virtual system construction, and analyzed Flight Control System that is applied to high altitude long endurance(HAE) UAS. Finally, we constructed the model based virtual Flight Control System with system analysis and achieved system verification about flight critical failure modes. Analysis target is RQ-4A.

A Study on Steady-State Performance Simulation of Smart UAV Propulsion System (신개념 비행체 추진시스템의 정상상태 성능모사 기법 연구)

  • 공창덕;강명철;기자영;양수석;이창호
    • Journal of the Korean Society of Propulsion Engineers
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    • v.7 no.3
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    • pp.38-44
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    • 2003
  • In this study, a performance model of the smart UAV propulsion system with ducts, tip jets and variable main nozzle, which has flight capability of the rotary wing mode for the take-off/landing and low speed forward flight as well as the fixed wing mode for high speed forward flight, has been newly developed With the proposed model, steady-state performance analysis was performed at various flight modes such as rotary wing mode, fixed wing mode, compound ing mode and altitude as well as at flight speed conditions. In investigation of performance analysis. it was noted that the operational capability of the propulsion system was limited due to the duct losses depending on each flight mode, and the limitation with the altitude variation case had much greater than that with the flight speed variation case.

A Study on Steady-state Performance Simulation of Smart UAV Propulsion System (신개념 비행체 추진시스템의 정상상태 성능모사 기법 연구)

  • 공창덕;강명철;기자영;양수석;이창호
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2003.05a
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    • pp.177-182
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    • 2003
  • In this study, a performance model of the Smart UAV propulsion system with ducts, tip jets and variable main nozzle, which has flight capability of the rotary wing mode for the take-off/landing and low speed forward flight as welt as the fixed wing mode for high speed forward flight, has been newly developed. With the proposed model, steady-state performance analysis was performed at various flight modes and conditions, such as rotary wing mode, fixed wing mode, compound wing, mode altitude and flight speed. In investigation of performance analysis, it was noted that the operational capability of the propulsion system was limited due to the duct losses depending on each flight mode, and the limitation with the altitude variation case has much greater than that with the flight speed variation case.

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Increasing Endurance Performance of Tiltrotor UAV Using Extended Wing (확장날개를 이용한 틸트로터 무인기 체공성능 향상)

  • Lee, Myeong Kyu;Lee, Chi-Hoon
    • Journal of Aerospace System Engineering
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    • v.10 no.1
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    • pp.111-117
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    • 2016
  • A new configuration of tiltrotor UAV previously suggested by Korea Aerospace Research Institute (KARI) for the purpose of increasing the endurance performance in airplane mode flight has extended wings attached to the nacelle and rotated with the nacelle according to the flight modes. In this research, the effectiveness of the extended wing on the enhancement of the endurance performance of KARI tiltrotor UAV (TR60) was analytically investigated based on CFD analysis results. Flight tests and ground tests of measuring the fuel consumption were also conducted to directly compare the endurance performance for the two configurations of TR60 baseline and TR60 extended-wing model.

Efficient Analysis of the Aerodynamic Characteristics of Rotor Blade Using a Reduced Order Model Based on Proper Orthogonal Decomposition Method (적합직교분해를 이용한 로터 블레이드의 차수축소모델 구축 및 공력특성 분석)

  • Jung, Sung-Ki;Duc, NgoCong;Yang, Young-Rok;Cho, Tae-Hwan;Myong, Rho-Shin
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.37 no.11
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    • pp.1073-1079
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    • 2009
  • The proper orthogonal decomposition (POD) method can identify principal modes that optimally capture the energy content from large multi-dimensional data set. In this study unsteady pressure fields on the rotor blade surface of a helicopter in forward flight are expressed by a reduced order model based on the POD method. Special modes containing high energy are analyzed to investigate the aerodynamic characteristics in more efficient way. The CFD simulation of flowfields around helicopter rotor blade in hovering motion is also conducted to validate its prediction with experimental result. In the process 7 modes containing energy ratio 99% from 240 snapshots information are identified and utilized to construct a reduced order model.

Development of Flight Safety Analysis System for Space Launch Vehicle (우주발사체 비행안전 분석시스템 개발)

  • Choi, Kyu-Sung;Ko, Jeong-Hwan;Sim, Hyung-Seok;Rho, Woong-Rae
    • Aerospace Engineering and Technology
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    • v.7 no.2
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    • pp.123-130
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    • 2008
  • Flight safety analysis, which includes risk estimation for the various abnormal flight modes in addition to normal flight, has to be performed necessarily to guarantee launch safety for the operation of space launch vehicles. For this purpose, a dedicated system has been developed such that all the necessary repetitive computations, result reports, and graphical presentations can be performed inside a single system for user convenience. In addition, the developed system is capable of representing computed results on a three dimensional Earth for the realistic presentation. The developed Flight Safety Analysis System will be employed for the launch operation of Korea Satellite Launch Vehicle-I.

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Probabilities of initiation of response modes of rigid bodies subjected to base excitations

  • Aydin, Kamil
    • Structural Engineering and Mechanics
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    • v.23 no.5
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    • pp.505-523
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    • 2006
  • An unrestrained plane rigid body resting on a horizontal surface which shakes horizontally and vertically may assume one of the five modes of response: rest, slide, slide-rock, rock, and free flight. The first four are nontrivial modes of motion. It is important to study which one of these responses is started from rest as in most studies it is often assumed that the initial mode is the particular mode of response. Criteria governing the initiation of modes are first briefly discussed. It is shown that the commencement of response modes depends on the aspect ratio of the body, coefficients of static and kinetic friction at the body-base interface, and the magnitude of maximum base accelerations. Considering the last two factors as random variables, the initiation of response modes is next studied from a probabilistic point of view. Type 1 extreme value and lognormal distributions are employed for maximum base excitations and coefficient of friction respectively. Analytical expressions for computing the probability values of each mode of response are derived. The effects of slenderness ratio, vertical acceleration, and statistical distributions of maximum acceleration and coefficient of friction are shown through numerical results and plots.

Development of Conceptual Design Methodology and Initial Sizing for Tip-Jet Gyroplane (Tip-jet gyroplane 개념설계 기법 개발 및 사이징)

  • Lee, Donguk;Lim, Daejin;Yee, Kwanjung
    • 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.

Longitudinal Flight Dynamic Modeling and Stability Analysis of Flapping-wing Micro Air Vehicles (날갯짓 비행 로봇의 세로방향 비행 동역학 모델링 및 안정성 해석)

  • Kim, Joong-Kwan;Han, Jong-Seob;Kim, Ho-Young;Han, Jae-Hung
    • 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.