ECERTA Project


Title :


Investigators :




Sponsor :



Enabling Certification by Analysis


Marques, S., Timme, S., and Badcock, K.J.


Khodaparast, H.H., Prandina, M., and Mottershead, J.E.


European Commission 6th Framework Programme


Open Source Fighter


Open Source Fighter Flowfield


Open Source Fighter Flowfield at Mach number 0.85 and angle of attack 2.12o

The Open Source Fighter configuration results from the efforts of trying to build a realistic size aeroelastic test case. The geometry is based on publicly available data for the F-16. The F-16 has a documented history of exhibiting LCOs for certain configurations at specific flight conditions. This prompts a significant research effort using this configuration.

Based on published data, the wing geometry was modified to produce similar aerodynamic characteristics to the F-16 (see figures 3 and 4). A structural model was also developed under the same approach: using finite model updating techniques and publicly available data from GVT, it was possible to construct a finite element model resembling specific natural frequencies.

Further details on the files available here are described in the following document (guide to files)

Variability Study

For the Open Source Fighter, six parameters were used to represent the structural variability. Due to the size of the model, MC analysis is not viable; instead interval analysis was the main tool to study the impact of variability on the onset of flutter. The structural model is made up of the fuselage and three regions along the wing span: root, middle (pylon) and tip; all these components have specific material characteristics, obtained from the finite element model updating procedure. To decrease the total number of parameters used in the variability study, a sensitivity analysis was performed and the following parameters were found to have the most significant impact on the onset of flutter:


Nominal Value

Allowed Variation

Store Spring Coefficient



Young's Modulus - Root

157.3 GPa


Young's Modulus - Middle

96.7 GPa


Material Density - Root

5680 kg/m3


Material Density - Middle

3780 kg/m3


Material Density - Tip

3780 kg/m3


Open Source Fighter CFD Based Interval Analysis - Real Eigenvalue


Open Source Fighter CFD Based Interval Analysis - Real Eigenvalue

MSC.Nastran and CFD Based Results

Open Source Fighter CFD Grid


CFD Fine Grid

Open Source Fighter MSC. Nastran Structural Model


MSC.Nastran Structural Model

Open Source Fighter C<sub>P</sub> Slice


CP at 59% Span - Comparison with F-16

Open Source Fighter C<sub>P</sub> Slice


CP at 85% Span - Comparison with F-16

CFD Based Damping Plot


CFD Based Damping Plot (ASCII Data)

CFD Based Frequency Plot


CFD Based Frequency Plot

Mode 1

Mode 2

Mode 3

Mode 4

Updated FE Model

3.74 (h1)

5.91 (p1)

8.12 (y1)

11.0 (hp)


4.04 (h1)

5.35 (p1)

8.12 (y1)

12.2 (h2)


Results from structural finite element model updating. The term hi indicates the ith bending mode; p1 indicates the pitch+torsion mode; y1 indicates the yaw mode, and hp indicates the bending+pitch mode.

Available Resources for Download

CFD Resources




Grid Format

(CGNS), (Tecplot)

MSC.Nastran Resources

Modal Analysis

Parametric Mode Generator

(Matlab Script)

Solver Input Files

Structural and Model Files


Conference Papers

  • Marques, S., Badcock, K.J., Khodaparast, H.H., and Mottershead, J.E., "CFD Based Aeroelastic Stability Predictions Under the Influence of Structural Variability," 50th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, Palm Springs, California, 4-7 May 2009.
    AIAA Paper 2009-2324

  • Marques, S., Khodaparast, H.H., Badcock, K.J., and Mottershead, J.E., "Transonic Flutter Predictions for a Generic Fighter Configuration," International Workshop on Fluid-Structure Interaction, Kassel University Press, Germany, 2009.