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Meeting | ACGS Committee Meeting 121 - Tucson, AZ - April 2018 | Agenda Location | 4 GENERAL COMMITTEE TECHNICAL SESSION 4.2 Research Institutions, Industry, and University Reports 4.2.1 Research Institutions and Companies 4.2.1.6 D. K. Schmidt & Associates | Title | D. K. Schmidt & Associates | Presenter | Dave Schmidt | Available Downloads* | presentation | | *Downloads are available to members who are logged in and either Active or attended this meeting. | Abstract | The overall goal of our research program is to use structural flexibility to an advantage so as to actively optimize transport-aircraft wing shape over the flight envelope, to minimize fuel requirements. Aeroservoelastic modeling and active flutter suppression are key enabling technologies, and extensive flight testing is being performed. Due in large part to the fact that design and testing of flight hardware is a focus, the team is highly interactive and well coordinated.
The focus of this presentation is to report on some aspects dealing with the validity of the mean-axis flight-dynamics modeling technique. This technique for modeling flexible aircraft frequently involves the assumption that the inertia tensor is constant, and that the rigid-body and elastic degrees of freedom are inertially decoupled. They are however coupled through the aerodynamics, of course. Further detailed analysis of the vehicles under study has confirmed that these assumptions are valid to engineering accuracy. While considering flight in an aggressive maneuver (2-g turn), the eigenvalues and eigenvectors of the dynamic system are unaffected by inertial coupling to three significant digits, and the flutter speed is essentially unchanged. But the validity depends on vehicle geometry and stiffness, so no general statements can be made. Hence, assessment of these assumptions is warranted for a given vehicle, and a key point is that for a specific vehicle the coupling terms can be evaluated from the finite-element model of the structure. | |
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