> Attached to this post you find my first setup with the background images.

Hi Ray, we won't be able to see the background images unless you attach those here too.

It may be useful to draw some lines or a rectangle before doing the background image, as a snapping guide.


> As you can notice when you select the fuselage, it seems to consist of four quarters
> instead of a complete surface or solid. Is it caused by an inaccuracy in my mirrored
> spline cross-sections? How can I detect such an error?

This is a side effect of blending some circles along with non-circles.

A NURBS circle is made up of 4 internal arc segments, although since they are fused together with a shared tangent, they will not automatically separate out with the regular "Separate" command.

For a lot of operations, this circle-segmentation does not cause a problem, but one area where it can cause a problem is when you loft between a circle and a regular curve - one part of the process of lofting is combining and blending together the different sections into a single surface and any kind of segmentation can become magnified at this point. What is happening is the segmentation is causing a small crease in the resulting surface, and MoI splits creased surfaces up into separate sheets.

This is something that I should be able to fix inside of loft - I should be able to detect the segmentation and re-approximate that curve with a single smooth non-segmented piece within tolerance which will then behave better.

Until then here is a workaround - turn on points for the circle and select one or more points and drag it. This is one area where MoI does the type of automatic re-approximation. If you drag any point on a circle and then drag it back (not undo it, that will restore the original circle which is not what you want) the "perfect but segmented" circle will be replaced with a fitted one that is one smooth non-segmented piece which will loft better.

So do that little "distrub point on circle" thing on each circle and you should then get a better result.



Filleting does work between two surfaces, but only if they are single individual surfaces, your fuselage in this case is made up of joined sections (due to the crease splitting), so that's why the surface/surface fillet is not happening there, in this case you probably should intersect the objects by trim/join or booleans and then do an edge fillet instead. But the little crease in the fuselage that is running right through that area probably is confusing things as well.

I'll see if I can improve the lofting to automatically handle this type of thing better.

- Michael