• Title, Summary, Keyword: Flight envelope protection

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Design of a Flight Envelope Protection System Using a Dynamic Trim Algorithm

  • Shin, Ho-Hyun;Lee, Sang-Hyun;Kim, You-Dan;Kim, Eung-Tae;Sung, Ki-Jung
    • International Journal of Aeronautical and Space Sciences
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    • v.12 no.3
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    • pp.241-251
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    • 2011
  • Most large commercial aircrafts and high performance military aircrafts use fly-by-wire (FBW) or fly-by-light systems to improve their controllability, comfort, and safety. A flight envelope protection technique is used with flight control systems utilizing the FBW technique. Such flight envelope protection systems prevent these aircraft from exceeding the structural/aerodynamic limits and control their surface limits. This is accomplished by predicting the values of the future state variables and adaptively compensating the control action. In this study, the conventional dynamic trim algorithm of the flight envelope protection is modified to increase the method accuracy and to handle cases with multiple variables. Numerical simulation is also performed to verify the performance of the proposed method.

Design of Flight Envelope Protection System on Velocity of Aircraft (항공기의 수평속도에 대한 비행영역 보호 시스템 설계)

  • Shin, Ho-Hyun;Lee, Sang-Hyun;Kim, You-Dan;Kim, Eung-Tae;Seong, Ki-Jung;Choi, Hyoung-Sik
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.38 no.4
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    • pp.327-334
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    • 2010
  • Recently developed aircrafts use Fly-By-Wire(FBW) or Fly-By-Light(FBL) system. These systems have some merits; they can perform very complicated missions, they can expand the flight region and improve the reliability of the aircrafts. With the development of flight control systems that use FBW technique, flight envelope protection concept is introduced to guarantee reliability of the aircraft and improve the efficiency of mission achievement. In this study, flight envelope protection system is designed using a dynamic trim algorithm, a peak response estimation, and a gain scheduling technique. The performance of these methods are compared by performing numerical simulation.

Study on Safe Set and Maneuverability Envelope Protection during Arresting Landing

  • Liu, Zidong;Zhan, Hao;Wang, Shuang
    • International Journal of Aerospace System Engineering
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    • v.2 no.2
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    • pp.73-78
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    • 2015
  • According to the characteristic of carrier-based aircraft, the method of solving safe set during arresting landing is discussed in this paper based on optimal control and invariant set theory. The safe sets of carrier aircraft are evaluated in different states on the characteristic of longitudinal augmented system by using the level set method. Then, the influence on the boundary of safe set under various factors is analyzed. At last, the maneuverability envelope protection is established based on the corresponding theory, and the validity of the system is verified through simulation. The results demonstrate preliminarily that: compared with mass and thrust, the elevator is the greatest influence factor for the boundary of safe set; the dynamic trajectory of carrier-based aircraft can be located at the interior of safe set effectively with the maneuverability envelope protection.

Flight Envelope Load Factor Limit Logic Design for Helicopter Fly-By-Wire Controller (전자식 조정장치 헬리콥터의 하중 비행영역 제한 로직 설계)

  • Choi, In-Ho
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.1
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    • pp.159-164
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    • 2016
  • This paper reports the load factor logic design for a fly-by-wire helicopter flight envelope protection. As a helicopter is very complex system with a rotor, fuselage, engine, etc., there are many constraints on the flight region. Because of these constraints, pilots should consider them carefully and have a heavy workload, which causes controllability degradation. In this respect, automatic logic is needed to free the pilot from these considerations. As one of these logics, the flight envelope protection logic for the load factor of a FBW helicopter was designed. The flight to exceed the load factor is caused by an abrupt pitch cyclic stick change. In this scheme, the load factor limit logic was added between the pilot stick command block and pitch attitude command block. From the current load value, the available attitude range was calculated dynamically and simulated on the helicopter simulator model to verify the performance. A comparison of the simulation results at the hovering and forward speed region with and without applying the load limiting logic showed that the load factor limit was exceeded more than 20% when the logic was not applied, whereas with the load factor limit logic the load factor was within the limit. In conclusion, a dynamically allocated limitation logic to helicopter FBW controller was verified by simulation.

Civil Aircraft Digital Fly-By-Wire System Technology Development Trend (민간항공기 디지털 Fly-By-Wire 시스템 기술 개발 동향)

  • Kim, Eung-Tai;Chang, Jae-Won;Choi, Hyoung-Sik;Lee, Sug-Chon
    • Current Industrial and Technological Trends in Aerospace
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    • v.7 no.2
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    • pp.85-94
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    • 2009
  • The Fly-By-Wire system was first applied to the fighter and its inherent advantages lead to the advent of the Fly-By-Wire civil aircraft. Recently even the small jet aircraft shows the trend of adopting the Fly-By-Wire system. In the future, most of the aircraft are expected to be the Fly-By-Wire type. In this paper, the structure and the characteristics of the Fly-By-Wire system applied to the civil aircraft was described. The development trend of the redundant method of the flight control system, data communication system, control surface actuation system and the control laws implemented by the Fly-By-Wire system of the civil aircraft are discussed.

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