wingAspectRatio

[MarAlder]

Currently the computation of the wing aspect ratio returns inf for the simpletest.cpacs.xml case because GetReferenceArea gets TIGL_X_Z_PLANE (symmetry axis) as input and consequently returns 0.

• example.zip

Not sure if my approach is better, but let's try: cdf5e853. I asked aircraft designers and for them the reference area is always the projection on the x-y-plane. Thus, I specified that directly.

I still have a bug in my code: If I remove the symmetry attribute in simpletest.cpacs.xml then GetSymmetryAxis() still returns TIGL_X_Z_PLANE. Could someone help me understand this? I just implemented the sym_axis variable for easier debugging. I also added the api method and implemented a unittest (:muscle:).

PS: not sure why I modifed tiglWingGetWettedArea as seen in the diff. Maybe I should have pulled once more. But let's focus on the aspect ratio for now.