In the attached file I have an armor plate that is 12.1" at the top and tapers at knuckles to 1.62". The knuckles are parallel to the base line. However, top edge slopes upwards in two segments linearly.
I created three frames to match the profile. The frames are identical except that the line defining the top facet and back facet increase in length with the upper profile moving with them.
If I do loft with straight sections split at tangets, cap, and merge all faces, I get the mess shown at the top of the figure.
As workaround, I
(1) removed one matching segment from each frame (creating an open polycurve)
(2) Loft with straight sections
(3) Merge all faces.
(4) PlanarSrf in the omitted area.
(5) Join all
That appears to give the correct answer.
Should Loft be able to figure this out with the closed curve?