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Center of pressure shows wrong aerodynamic force vector


Anonymous Bug Reporter

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Reported Version: v0.1.5 (latest) | Mods: none | Can replicate without mods? Yes 
OS: Linux/Proton | CPU: Ryzen 3800X | GPU: Radeon 6700XT | RAM64Gb

 

Hello,

I'm having trouble building the craft, with aerodynamic forces applied (or at least shown) incorrectly.

At start, when a vessel is constructed for the first time, the aerodynamic forces are shown correctly. However, after a few iterations of attempted launch/modifications the aerodynamic forces as shown by "center of pressure" gimbals become skewed to one side, with no way to change that. This could be seen in the screenshot, with pressure force shown to be directed to the left, while the stabilizer is straight.

 

 

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20231029224053_1.jpg.578af42607031eb1d6ea3fc5f9266459.jpg

Edited by The Space Peacock
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  • 2 weeks later...

That's a wing, not a stabilizer. It applies lift orthogonal in one direction (asymetric profile). Displayed is the lift the surface would produce at 0° angle of attack.

So some lift pointing sideways is to expected if you place just a single wing without radial symmetry. The curious part is that the lift from the main wings has gone missing in the preview, that lift vector is now only from your rudder.

The actual issue appears to be that lift for wings is displayed incorrectly at seemingly random for axis-aligned wings - it's off 180° when that happens, potentially negating the lift vectors from symmetric parts. If you tilt the entire craft just slightly off-axis, all wings which are no longer axis-aligned now have the lift previewed correctly again.

 

Easy way to reproduce this? Take just a single wing and mount it horizontally, then rotate it up-side down. Increase the thickness of the wing so you can clearly see the profile, to make sure you got it right (curved side should be on the bottom now!).

Now as long as the wing is exactly horizontal (even though already upside down!), it will preview lift as if the lift vector was pointing straight up. Tilt the wing just by 5° in either direction, and suddenly the lift vector flips upside down as it should.

If you add more wings, you will then find that it's the individual wings components vectors which have their signs incorrectly flipped.

Edited by Ext3h
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