• 제어로봇시스템학회논문지
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• 제20권11호
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• pp.1103-1111
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• 2014

The results of control law design for a tilt-rotor unmanned aerial vehicle that has a nacelle mounted wing extension (WE) are presented in this paper. It consists of a control surface mixer, stability and control augmentation system (SCAS), hold mode for altitude / speed / heading, and a guidance mode for preprogram and point navigation which includes automatic take-off and landing. The conversion corridor and the control moments derivatives between the original tilt-rotor and its variant of the nacelle mounted WE were compared to show the effectiveness of the WE. The nacelle conversion of the original tilt-rotor starts when the airspeed is greater than 30 km/h but its WE variant starts at 0 km/h in order to reduce the drag caused by the high incidence angle of the WE. The stability margins of the inner loop are presented with the optimization approach. The outer loops for the hold mode are designed with trial and error methods with linear and nonlinear simulation. The main control parameter for altitude control of the helicopter mode is thrust command and it is transferred to the pitch attitude command in airplane mode. Otherwise, the control parameter for the speed of the helicopter mode is the pitch attitude command and it is transferred to the thrust command in airplane mode. Therefore the speed and altitude hold mode are coupled to each other and are engaged at the same time when an internal pilot engages any of the altitude or speed hold modes. The nonlinear simulation results of the guidance control for the preprogrammed mode and point navigation are also presented including automatic take-off and landing in order to prove the full control law.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2006년 제4회 한국유체공학학술대회 논문집
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• pp.427-430
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• 2006

The ground effect on tilt-rotor UAV is analyzed by simulating the hovering UAV for various altitudes. Ground effect increases pressure beneath the UAV body and generates additional lifting force. The ground effect diminishes at altitude 3m and hovering UAV generates constant lifting force above 3m.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2011년도 제37회 추계학술대회논문집
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• pp.389-392
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• 2011

본 연구에서는 틸트로터 비행체인 스마트무인기의 비행시험에서 엔진성능 데이터를 추출하고 분석하였다. 비행시험은 프롭로터의 틸트각이 90도에서 0도로 변화하고 다시 0도에서 90도로 변환하는 천이비행 영역에서 이루어졌다. 비행시험으로부터 수집된 엔진성능 데이터로서 엔진 동력과 비연료 소모율은 엔진성능계산프로그램의 예측결과와 잘 일치하였다.

• 한국항공우주학회지
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• 제42권9호
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• pp.731-738
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• 2014

오늘날 무인기는 기술 발전을 통해 육해상의 다양한 분야에서 이용되고 있다. 한국항공우주연구원(KARI)에서는 육상용 수직이착륙기로 개발된 틸트로터 무인기를 해상에서 운용할 수 있도록 임무영역 확장을 고려하고 있다. 틸트로터 무인기의 효과적인 해상운용을 위해서는 함상이착륙이 필요하지만 해상은 지상에 비해 염분, 연무, 바람등 기상영향을 많이 받는다. 또한 지상과는 달리 선박 운동으로 인한 착륙지점의 운동이 발생하며, 자동 함상착륙을 어렵게 만든다. 이러한 무인기 함상이착륙을 위하여 본 논문에서는 파고에 따른 선박 운동을 모델링 하고, 무인기 시뮬레이터를 통해 시험평가한 결과를 제시하고 있다.

• 항공우주시스템공학회지
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• 제1권2호
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• pp.27-36
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• 2007

The Damage Tolerant Design is developed to help alleviate structural failure and cracking problems in aerospace structures. Recently, the Damage Tolerant Design is required and recommended for most of aircraft design. In this paper, the damage tolerant design is applied to tilt rotor UAV. First of all, the fatigue load spectrum for the tilt rotor UAV is developed and fatigue analysis is performed for the flaperon joint which has FCL (fatigue critical location). Tilt rotor UAV has two modes: helicopter mode when UAV is taking off and landing; fixed wing mode when the tilt rotor UAV is cruising. To make fatigue load spectrum, FELIX is used for helicopter mode. TWIST is used for fixed wing mode. Fatigue analysis of flaperon joint is performed using fatigue load spectrum. E-N curve approach is used for picking crack initiation point. The LEFM(Linear Elastic Fracture Method) is considered for analyzing crack growth or propagation. Finally, including the crack initiation and propagation, the fatigue life is evaluated. Therefore the Damage Tolerant Design can be done.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.821-825
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• 2005

Tilt rotor aircraft was developed for satisfying VSTOL (vertical short take off and landing) capability and cruise performance. However the noise generated by tilt rotor system causes one of the most serious problems. In this paper, noise characteristics of tilt rotor system in hovering flight are predicted by using free wake method and Lowson's formula. The flow field of the tilt rotor is simulated by using time marching free wake method, and the free field acoustic pressure is calculated through Lowson's formula. The predicted results are compared with experimental data at various observing positions. In the near field, they show good agreement with experimental data regardless of rotating speed and collective pitch angles of 6, 8 and 10 degree, although there are some discrepancies between prediction and experiment in the far field and at the rotating axis in the near field. It seems that the reason of these discrepancies is difference of unsteady force fluctuation between experiment and calculation.

• 대한기계학회논문집A
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• 제31권5호
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• pp.625-634
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• 2007

KARI SUAV program was initiated to develop a Smart Unmanned Aerial Vehicle with innovative smart technologies. SUAV is a tilt rotor aircraft of which rotor system is 3-bladed, gimbaled hub type. Several existing concepts of gimbaled hub were analyzed and compared to investigate the applicability to SUAV rotor system design. From the result of these investigations, it was concluded that a new design concept of low cost and high reliability characteristics was necessary for the rotor hub development of SUAV. The design requirements of new gimbal hub concept and the design results were presented. Also, the analysis results to verify the satisfaction of design requirements of SUAV rotor system were presented.

• 한국항공우주학회지
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• 제34권1호
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• pp.8-17
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• 2006

• 한국항공운항학회지
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• 제13권2호
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• pp.14-26
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• 2005

A tilt-rotor aircraft has various flight modes : helicopter, airplane, and conversion. Each of flight mode has unique and nonlinear flight characteristics. Therefore the gain schedules for whole flight envelope are required for effective flight performance. This paper proposes collective, flap, and nacelle angle scheduler for whole flight envelope of the Smart UAV(Unmanned Air Vehicle) based on CAMRAD(Comprehensive Analytical Model of Rotorcraft Aerodynamics and Dynamics) II analysis results. The scheduler designs are improved so that the pitch attitude angle of helicopter mode was minimized. The range of scheduler are reduced inside of engine performance limits. The conversion corridor and rotor governor are suggested also.

• 항공우주기술
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• 제12권1호
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• pp.10-21
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• 2013

오늘날 헬리콥터 기술의 발전과 더불어 함상에서 헬리콥터를 운용하는 것은 당연한 것으로 여겨지고 있다. 육상과 달리 해상에서 항공기를 운용하기 위해서는 육상보다 심한 바람과 파도와 배의 이동에 의한 착륙장의 운동과 염분에 의한 장비의 부식이 고려되어야하며 안전한 운용을 위한 운용절차가 요구된다. 본 논문에서는 수직이착륙 항공기의 함상운용 사례분석을 통하여 함상운용에 요구되는 항공기와 선박의 고려사항과 운용절차를 알아보고 이를 기반으로 틸트로터 무인기의 함상운용 기술개발 방안을 제시한다.