I'm sure this is possible - but I have limited knowledge when it comes to sheet metal sweeps/lofts. Pictured below is an image of the assembly I'm going for. Sheet metal panels are joined at various segments to create a helix "ribbon". Now, I need to create small panels that fit the curvature of the helix.. to create "flanges". This is best shown at the top and bottom of the assembly. However, only the top and bottom can the panels be planar. The piece circled is the one I'm having a problem with:

(And a closer image) The small red line indicates the amount the panel must be bent in order to match the bottom edge of the helix panel:

I would like to be able to create a plane on the edge of the helix panel segment, and work from that to get the correct curve.. but because it is not planar.. I can't create a plane, haha. Also, this needs to be sheet metal - so when the time comes, I can provide a flat pattern for fabrication purposes.

Again, this is a little outside of my understanding, so I could really use some insight/help to finish this project.

I have attached a zip file with the model I'm currently working with. 

Thanks in advance for any guidance!