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Aircraft Drag Determination in Frequency Domain Using Parametric Identification Methods

Ramezani Dehaghi, Hassan | 2011

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 42474 (45)
  4. University: Sharif University of Technolog
  5. Department: Aerospace Engineering
  6. Advisor(s): Banazadeh, Afshin
  7. Abstract:
  8. Determination of drag force is one of the most difficult activities in the design and development of an aircraft. Accurate estimation of drag force is very important in design studies and needs to be estimated over and over during the design trade-offs. Importance of the determination of drag force, from the performance viewpoint, is an important stage in development and evaluation of an aircraft behavior and if the thrust and drag forces are well determined, the other performance characteristics could be easily estimated. Different methods are introduced for determination of drag using flight test or system identification methods in the time domain owing some limitations, disadvantages or simplifying assumptions. On the other hand frequency response method has shown promising results in flying vehicle applications. Because of the advantages of this method in comparison with time domain identification, in the current dissertation it is intended to identify an accurate state space model utilizing the capabilities of this method. Since the identified parameters in state space matrices are stability derivatives and drag coefficients are present in these derivatives, it could be determined accurately. In this thesis, after giving a brief history about drag force and determination methods by flight test data, the frequency response identification method is introduced. Since all the identification methods rely on flight data, non-linear simulation code is developed to generate this data. Then an optimal input is designed and state space equations and drag coefficient are identified. The results of this thesis can be used for determination of fixed wing aircraft drag characteristics
  9. Keywords:
  10. Drag Coefficient ; System Identification ; Frequency Domain ; Nonlinear Simulation ; Optimal Input ; CIFER Software

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