Surface loft with 2 rails causing bizarre shapes.

[akschu]

Task is pretty simple, I have a wing profile on one axis, and a 3d spline which defines where I want the edge of the wingtip to be with two rails because I want the wing to have a blunt edge towards the front that tapers to a sharp point towards the edge.

If I surface loft the top edge of the profile to the tip I using the first rail I get a decent shape:

But, if I add the second rail I get this super aerodynamic shape:

I can't for the life of me figure out why?  

Is this a reasonable way to draw a wingtip or am I barking up the wrong tree?

[johnsonshiue]

Hi! You may need to use two Lofts to create the shape. Or some tweaks on the sections or rails are required. Please share the f3d file here. The forum experts can help take a closer look.

Many thanks!