Hi Kevin,

> Yes, seems to be a problem with software as that edge was
> used to create the new surface so why isn't it a perfect match
> suitable for joining ? Possibly it springs apart due to tensions
> in the nurbs surfaces.

It looks like that particular edge was fine, however the one on the bottom that is supposed to touch it does not touch it. Here I deleted the surfaces and zoomed in:






When you do a Network the surface that is generated will be kind of an average of those curves, if you have a bottom piece that does not touch the side one, then the averaging action will pull the created surface away from the side.

To fix this, make sure that your initial curve network has ends that match up exactly and then the generated surfaces will also match exactly and should join together.


If your curve network has gaps in it, then the surfaces created from them will also have gaps.


Building the main fuselage as one long simple tube instead of a patchwork of pieces would probably avoid this as well though.

- Michael