Type of Document Master's Thesis Author Stagg, Gregory A. URN etd-110498-091714 Title An Aerodynamic Model for Use in the High Angle of Attack Regime Degree Master of Science Department Aerospace and Ocean Engineering Advisory Committee
Advisor Name Title Lutze, Frederick H. Jr. Committee Chair Anderson, Mark R. Committee Member Durham, Wayne C. Committee Member Keywords
- Pitching Moment
- Normal Force
- Rolling Moment
- Aerodynamic Modeling
- High Angle of Attack
Date of Defense 1998-12-02 Availability unrestricted AbstractHarmonic oscillatory tests for a fighter aircraft using the
Dynamic Plunge--Pitch--Roll model mount at Virginia Tech Stability
Wind Tunnel are described. Corresponding data reduction methods are
developed on the basis of multirate digital signal processing. Since
the model is sting mounted, the frequencies associated with sting
vibration are included in balance readings thus a linear filter must
be used to extract out the aerodynamic responses. To achieve this, a
Finite Impulse Response (FIR) is designed using the Remez exchange
Based on the reduced data, a state--space model is developed to
describe the unsteady aerodynamic characteristics of the aircraft
during roll oscillations. For this model, we chose to separate the aircraft
into panels and model the local forces and moments. Included in this
technique is the introduction of a new state variable, a separation
state variable which characterizes the separation for each panel.
This new variable is governed by a first order differential equation.
Taylor series expansions in terms of the input variables were performed
to obtain the aerodynamic coefficients of the model. These
derivatives, a form of the stability derivative approach, are not
constant but rather quadratic functions of the new state variable.
Finally, the concept of the model was expanded to allow for the
addition of longitudinal motions. Thus, pitching moments will be
identified at the same time as rolling moments. The results show that
the goal of modeling coupled longitudinal and lateral--directional
characteristics at the same time using the same inputs is feasible.
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