Compensation on deployment of airbrakes and lessons learned from LCA flights

Lakshmi, P and Patel, Vijay V and Deodhare, Girish S and Chetty, Shyam (2008) Compensation on deployment of airbrakes and lessons learned from LCA flights. In: Proceedings of the International Conference on Aerospace Science and Technology (INCAST 2008-083), 26-28 Jun 2008, Bangalore, India.

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    Abstract

    The airbrakes are part of high performance aircraft and its location is arrived at based on wind tunnel experiments and in actual practice it is a compromise between the x2018;desiredx2019; location, which gives the least pitching moment and the best x2018;availablex2019; location on aircraft x2018;near to the desired onex2019;. The requirement is such that on deployment of airbrakes the drag should increase without any decrease in lift. If the airbrakes are not installed at the x2018;desired locationsx2019;, aircraft starts pitching up and x2018;pitch upx2019; increases with the airspeed. The x2018;idealx2019; requirement is that when airbrakes are deployed pilot should be able to concentrate on his mission without making an effort towards controlling the pitching moment. Thus, it is necessary to automatically compensate the pitch up tendency of the aircraft on deployment of airbrakes, and can be implemented in the Digital Flight Control Computer (DFCC) software.13; This paper addresses the design of the automatic pitching moment compensation loop on deployment of airbrakes. The pitching moment compensation is implemented as a feed forward loop and hence, can be designed independent of the feedback control laws. It is very important to model all the nonlinearities related to the airbrakes very accurately, since the pitching moment compensation loop is in the feed forward path. Therefore, any delays or nonlinearities affect the performance significantly.

    Item Type: Conference or Workshop Item (Paper)
    Additional Information: Copyright for this article belongs to National Aerospace Laboratories
    Uncontrolled Keywords: Airbrakes;Digital flight control computer;Aerodynamic brakes;LCA
    Subjects: AERONAUTICS > Aeronautics (General)
    Division/Department: Other, Other, Other, Flight Mechanics and Control Division
    Depositing User: Ms. Alphones Mary
    Date Deposited: 11 Mar 2009
    Last Modified: 17 Jun 2010 14:38
    URI: http://nal-ir.nal.res.in/id/eprint/5012

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