Set wing chord

[Alexandre Bdx]

Hello,

I'm having a little bit of trouble understanding how the chord is defined. I looked at the Traditional Airplane example and notice that when it is plotted the chord seem to be 2 on all the wings. However, the default value for chord (which is not specified in traditional_airplane.json) is 1.

Changing the chord value did not seem to have an impact as long as reference was defined with custom parameters. However, once reference was deleted and its parameters taken from the main wing, I was able to set the chord. But the value showed in the plot is always double the chord I set.

Additionally, I was not really able to set the chord for the other wings (h stab and v stab): they seem to somewhat depend on the main wing setting.

Could you please clarify how the chord can be set for each wing? Thanks!

Alex

[Cory]

Alex

If you could post your input files to show how you're defining the chord, that should help.

The traditional airplane example does have a chord of 1 for all wings. Maybe you're interpreting the trailing vortices (the blue dashed lines) as part of the wing?

Each wing's chord is defined independently.

Thanks

Cory

[Alexandre Bdx]

Ah that makes sense! I was looking at the entire area spanned by the blue dashed line, not the solid rectangles. I attached the config I used (I only added the "chord" parameter for the main wing) but the display now matches the settings from what I can see.

Two things:

- On the display, it seems that the front of the main wing is not aligned with y=0 (see screenshot). Why is that?

- What drives the length of the trailing vortexes on the display?

Thanks!

Alex

[Cory]

Great! The front of the wing is not aligned with y=0 because all geometry is defined relative to the wing quarter-chord. So the root quarter-chord point is at the origin if an offset is not given. This is just standard for aerodynamic design. The length of the trailing vortices is simply 2 times the local chord length. It has no real physical meaning; it's just meant to be a way to visualize the numerical discretization.