• Title, Summary, Keyword: Compound helicopter

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Validation on Conceptual Design and Performance Analyses for Compound Rotorcrafts Considering Lift-offset

  • Go, Jeong-In;Park, Jae-Sang;Choi, Jong-Soo
    • International Journal of Aeronautical and Space Sciences
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    • v.18 no.1
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    • pp.154-164
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    • 2017
  • This work conducts a validation study for the XH-59A helicopter using a rigid coaxial rotor system in order to establish the techniques of the conceptual design and performance analysis for the lift-offset compound rotorcraft. As a tool for conceptual design and performance analysis, NDARC (NASA Design and Analysis of Rotorcraft) is used for the present study. An assumed mission profile is considered for the conceptual design of the XH-59A. As a validation result of the design, the dimensions and weight of the XH-59A are appropriately designed when compared to the target values since the relative error is less than 0.5%. Then, performance analyses are conducted for the designed XH-59A model with and without auxiliary propulsion in hover and forward flight conditions. The present analyses show good validity since the prediction results compare well with both the flight test and previous analyses. Therefore, the techniques for the conceptual design and performance analysis of the lift-offset compound helicopter are overall considered to be appropriately established. In addition, this study investigates the influence of the lift-offset on the rotor effective lift-to-drag ratio of the XH-59A helicopter with auxiliary propulsion. As a result, the improvement of the rotor effective lift-to-drag ratio can be obtained by appropriately increasing the lift-offset in high-speed flight.

Further Improvement in Rotor Aerodynamics Estimation in Helicopter Conceptual Design and Optimization Framework for a Compound Rotorcraft

  • Lim, JaeHoon;Shin, SangJoon;Kee, YoungJung
    • International Journal of Aeronautical and Space Sciences
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    • v.18 no.4
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    • pp.641-650
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    • 2017
  • In order to include the design capability for a compound rotorcraft in a helicopter conceptual design and optimization framework, relevant further improvement was planned and conducted. Previously, a certain conceptual design optimization framework was developed by the present authors to design a modern rotorcraft with single main and tail rotor. The previously developed framework was further improved to expand its capability for a compound rotorcraft. Specifically, its power estimation algorithm was upgraded by using a comprehensive rotorcraft analysis program, CAMRAD II. The presently improved conceptual design and optimization framework was validated using data of the XH-59A aircraft.

An Exploratory Study on the Speed Limit of Compound Gyroplane(2) : Speed and Wing Sizing (복합 자이로플레인의 한계 속도에 대한 탐색연구(2) : 속도 및 날개 사이징)

  • Shin, Byung-Joon;Kim, HakYoon
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.43 no.11
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    • pp.978-983
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    • 2015
  • A study on the speed limit and sizing of auxiliary fixed-wing of compound gyroplane was performed. The performance of the plane that uses the same rotor system and power of BO-105 helicopter was compared with that of BO-105 helicopter. The wing area which is used to compensate in lift, was calculated considering the aerodynamic characteristics and lift sharing ratio of the rotor. Achievable flight speeds were observed for two types of fuselage; BO-105 and streamlined bodies. The study showed that the autorotating rotor can share 1/2 of lift at high speed and the parasite power of compound gyroplane having streamlined body and small wing can be minimized, accordingly it can fly faster than helicopter with airspeed more than twice.

Design of Lateral SCAS based on H for Tilt Rotor Aircraft (H 기반 틸트로터 항공기 횡방향 SCAS 설계)

  • Lee, Jangho;Yoo, Changsun;Walker, Daniel J.
    • Journal of Aerospace System Engineering
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    • v.2 no.3
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    • pp.1-6
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    • 2008
  • The tilt rotor aircraft has the flight characteristics which takes off vertically like a helicopter and flies forward like an airplane. Especially, the transition process from a helicopter to an airplane mode requires not only the mixing of control inputs but also the stability and controllability augmentation system(SCAS) in order to keep the safe flight because there are compound flight dynamic characteristics of a helicopter and an airplane including non-linearity, uncertainty. This paper describes the design of SCAS in a lateral motion for the tilt rotor aircraft based on the $H_{\infty}$ control method, which was performed from mathematical model with weighting matrix based on the relationship between the $H_{\infty}$ norm and the sensitivity function. Through simulation analysis for the controller designed on the $H_{\infty}$ control theory, it was shown that this method may be applied to the control design of the tilt rotor aircraft.

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Developmental Trends of High Performance Rotorcraft and the Analytic Method of Autorotation (고성능 회전익기의 개발동향과 자동회전의 해석기법)

  • Kim, Hak-Yoon;Sheen, Byung-jun
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.22 no.3
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    • pp.60-67
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    • 2014
  • Technical history of VTOL aircraft is examined from the early helicopter appearance to recent experimental rotorcraft in order to distinguish the core issues of those aircraft. Performance and technological challenges of some VTOL aircraft such as tilt rotor, convertiplane, gyroplane, and coaxial helicopter are discussed. As a new generation high performance rotorcraft, Sikorsky X2 is intensively investigated. Considering the developmental history of X2, the autorotational ability at high speed is recognized as a core technology. Analytic method of autorotation and some results are shown and presents research subjects related to the future Korean high performance rotorcraft.

Performance Analysis of Autorotation(2) : Performance of High Speed Autorotaion (자동회전의 성능해석(2) : 고속 자동회전의 성능)

  • Kim, Hak-Yoon
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.40 no.1
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    • pp.12-22
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    • 2012
  • Performance variation of autorotating rotor was investigated. The shaft angle of the rotor is reduced while the flight velocity is increased. The BO-105 helicopter rotor blade was replaced by untwisted NACA 0012 airfoil and the rotor was simulated by using Transient Simulation Method(TSM) to judge the autorotation region for the variables. To simulate the compressibility effect at high speed flight, two-dimensional aerodynamic data was analyzed by compressible Navier-Stokes solver and Pitt/Peters inflow theory was adopted to simulate the induced velocity field. Thrust and lift coefficients, lift to drag ratio variations were investigated, also the lift and power were compared to those of BO-105 helicopter. Sharing lift and power between the autorotating rotor and wing was considered when the compound aircraft concept is introduced.

Performance and Airloads Analyses for a Rigid Coaxial Rotor of High-Speed Compound Unmanned Rotorcrafts (고속 비행 복합형 무인 회전익기의 강체 동축반전 로터의 성능 및 공력 하중 해석)

  • Kwon, Young-Min;Park, Jae-Sang
    • Journal of the Korea Institute of Military Science and Technology
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    • v.23 no.4
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    • pp.311-318
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    • 2020
  • This study investigates the performance and blade airloads for a rigid coaxial rotor of high-speed compound unmanned rotorcrafts. The present compound unmanned rotorcraft uses not only a rigid coaxial rotor, but also wings and propellers for high-speed flights. For the rigid coaxial rotor in this work, CAMRAD II, a rotorcraft comprehensive analysis code, is used to study the performance at a flight speed of up to 250 knots and blade section lift forces at 230 knots. As the flight speed increases, the rotor power decreases; however, the power of propellers increases to overcome the drag force of a rotorcraft in high-speed flight. The effective lift-to-drag ratio of a rotor has the maximum value of about 11.6 which is much higher than the value of the conventional helicopter. The blade section lift forces of the upper and lower rotors at 230 knots show the similar variation trends for one rotor revolution, and the impulses because of the aerodynamic interaction between both rotors are observed.

Numerical Investigation of Forward Flight Characteristics of Multi-Ducted Fan (다중 덕트 팬 전진 비행 특성에 대한 수치적 연구)

  • Roh, Nahyeon;Oh, Sejong;Park, Donghun
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.46 no.2
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    • pp.95-105
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    • 2018
  • Increasing cruise speed is an important issue for the development of the next generation rotorcraft. Among several concepts proposed by previous research, the rotorcraft with ducted fan demonstrates its possibility of high-speed flight. In this study, numerical simulations are conducted to investigate the aerodynamic and flow characteristics of multi-ducted fan in forward flight. The aerodynamic efficiency around front ducted fan is determined by interaction between free-stream velocity and the induced velocity. While flow characteristics of rear ducted fan are dominantly influenced by the front ducted fan. Separation in the front ducted fan occurs faster than that of rear ducted fan, and the separation at duct inlet induces an increase of fan thrust. As a result of interaction effect between each ducted fan, relatively aligned inflow enters to the rear ducted fan. Therefore, thrust of the rear fan is decreased steadily before separation, and sudden changes of thrust in fans occur simultaneously. Due to the pressure decrease on lower surface, the normal force of rotorcraft is reduced with forward speed.

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.

Development of Preliminary Conceptual Design/ Comprehensive Analysis Programs for Next Generation Rotorcraft (차세대 회전익 기본개념설계/통합해석 프로그램의 개발)

  • Oh, Sejong;Park, Donghoon;Ji, Hyung Min
    • 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.