Undesired T-spline edge behavior

[nvetters]

I'm designing a UAV and am using a T-spline to create the lifting body fuselage. I used the match tool to interface with the airfoils of the wings, but on the canard here it's showing baffling behavior where it bulges unexpectedly. It's ugly and will negatively impact aerodynamic performance. Normally I can control edge behavior pretty well, but no matter what I do this one little bit insists on being shaped like this. I'm attaching a few images of the problem area and the main wing that behaved better for reference, as well as a simplified version of the model. If anyone can figure out why it's doing this that would be wonderful. The model does contain some T and star points, but not near the anomaly.

[adam.helps · Accepted solution]

You might have some tangency handles that are positioned in an unfortunate way. Try turning on Edit Form and switch to 'Vertex' selection mode. This will make all the tangency handles appear. The manually adjusted tangency handles are red squares. See if you spot any near the problem area.

If you click on the red ones, a 'Link' icon will appear in the Edit Form window. Clicking this will switch the tangency handle back to its "automatically positioned" mode (and it will change to a green circle).

There's nothing actually wrong with manually adjusted tangency handles. The reason they're there is to give you more control over the shape of the boundary. It's mainly a problem when you don't know they're there and aren't sure how to fix them.

[glenn-chun]

Rather than individually link tangent handles, you can do a window select and link them all. You can even do a window select for the entire body.

[TrippyLighting]

I would not try to match, or connect the T-Spline directly to the wing. To match the wing profile you need more segments /edges that you really need to get a smooth fuselage shape as evidenced already in your model.

Roughly  approximate the wing profile with the T-Spline and leave some distance between it and the wing. Bridge it with a loft and appropriate tangency settings.

[nvetters]

Oh, I was unaware that you could manipulate the tangent handles. That's all I needed, thank you! I've got it fixed now. One was way out of whack, not sure how it got like that.

[TrippyLighting]

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@nvetters wrote:

Oh, I was unaware that you could manipulate the tangent handles. That's all I needed, thank you! I've got it fixed now. One was way out of whack, not sure how it got like that.

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I would not touch those tangent handles! Re-read my message.

[nvetters]

Yes, I re-linked them all. I just didn't know they could be manipulated, so I didn't know that could be a problem. Thanks again!

[TrippyLighting]

I believe I said in MY reply that relinking is not the right technique to achieve what you want to do.

Your T-Spline is already too dense (too many edge loops) for the simple shape it represents. It’s topology is very uneven.