Hi quat, the Network command is expecting to have curves set up so that there are 2 sets of curves that cross over each other, like this for example:



In that example one direction has 5 curves going in one direction:

And 3 curves in the other direction crossing over the other set:


The file that you posted, aerofoil.3dm does not have curves arranged like this, you only have curves going in one direction with no other set crossing over them, so that curve structure is not suitable for use with the Network command.

You could use the Loft command on your curves though, Loft is expecting curves that are cross sections in one direction only instead of a crossing grid like Network.

- Michael