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SACCON Stability and Control Analysis Applying System Identification Techniques

Rohlf, Detlef and Schmidt, Stefan and Irving, Jonathan (2010) SACCON Stability and Control Analysis Applying System Identification Techniques. AIAA 40th Fluid Dynamics Conference , 27.06.-01.07.2010, Chicago, USA.

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Different methods are described to determine dynamic derivatives of an UCAV configuration named SACCON (Stability And Control CONfiguration). These methods can be applied to both experimental and computationally obtained data sets. The method applied by DSTO assumes a linear derivative model and is based on a least-square curve-fitting technique and a subsequent avaluation step to actually compute the derivatives themselves. Based on the unsteady simulation obtained by computational fluid dynamics, the DSTO routine is able to recover the major thrends of vehicle performance with reasonable agreement for pitching stiffness and damping. Lift-related quantities do show a discrepancy, particularly at high angle-of-attack. The BAE Systems approach also assumes a linear derivative model. In this case however, the static pitching stiffness terms are defined explicitly from the static test results and then subtracted from the dynamic results to give the residual effect of the damping terms. A least squares fit of these is used to determine the damping derivatives. Using this approach, it is demonstrated that the linear derivative assumption falls down at higher angle-of-attack (AoA) and a more generalized modeling paradigm is required, e.g., as developed by DLR. The DLR approach enables the use of nonlinear model equations and is therefore applicable to the entire tested angle of attack and angle of sideslip regime generating a single set of nonlinear derivatives. Thus, the hysteresis loops of the coefficients derived from dynamic wind tunnel tests can be reproduced satisfactorily with most of their inherent significant changes depending on angle of attack and forced oscillation frequency.

Document Type:Conference or Workshop Item (Speech)
Title:SACCON Stability and Control Analysis Applying System Identification Techniques
AuthorsInstitution or Email of Authors
Rohlf, DetlefDLR, Institute of Flight Systems, Braunschweig, Germany
Schmidt, StefanDSTO, AVD, Flight Systems, AUSTRALIA
Irving, JonathanBAE-Systems, Military Air Solutions, Flight Dynamics R&T, UK
Date:12 May 2010
Refereed publication:Yes
In ISI Web of Science:No
Keywords:Results achieved within the RTO AVT-161 Task Group, improve the ability to accurately predict both static and dynamic stability of general air and sea vehicles using computational fluid dynamics (CFD).
Event Title:AIAA 40th Fluid Dynamics Conference
Event Location:Chicago, USA
Event Type:international Conference
Event Dates:27.06.-01.07.2010
HGF - Research field:other
HGF - Program:Aeronautics
HGF - Program Themes:Aircraft Research
DLR - Research area:Aeronautics
DLR - Program:L AR - Aircraft Research
DLR - Research theme (Project):L - Systems & Cabin
Location: Braunschweig
Institutes and Institutions:Institute of Flight Systems > Flight Dynamics and Simulation
Deposited By: Tanja Bracke
Deposited On:21 Jun 2010 14:17
Last Modified:21 Jun 2010 14:17

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