Error when multi section surface.

I face problem when trying to join the two surface together. The upper surface was done exactly like what was shown in the pictures. It just so happens that the bottom part cannot be connected. I keep getting errors like this. Anyone has any idea on how to blend the winglet to the airfoil as blended as possible?

2 Answers

The error message says the Spine curve is too short. So, define the Spine as the longest guide curve (Connect.3) and see if that works.

(I'm surprised you didn't add tangent continuity to your design)

Simple, align those arrow marks on same side.