Boeing 727-100 triple-slotted Fowler flaps.

This reference photo shows the parts I have to build… Three individual flap segments, a jackscrew, a flap track for the flaps to ride on, and a hinged flap track fairing.

You'll see in recent images of the wing, I had built a single-piece (inboard and outboard) flap, and had positioned slices to show me where the three flap segments went. So, I began by creating two copies (for a total of three) of each of those flap pieces. That way, I could slice off the appropriate parts, and remodel the leading or trailing edges, to create the shapes you see below.

Here's the center (main) flap segment, which is the largest.

Next, the trailing edge segment (most aft) fits inside the main segment.

Finally, the leading edge segment (most forward) fits on top of the main segment.

Here are the flaps in the "up" position, with the spoilers creating the "slot lip".

Here's a render with all parts in the "up" position, with the spoilers open.

Cutaway views of the model as it stands today:

These images are actually 1200 pixels wide. Drag them to your desktop to see the large version.

Flaps in the down position:

These are not yet "rigged". I simply made duplicates of the flaps, and positioned one copy in the full down position.

A few renders with all the major parts modeled:

Done, for now…

At a file size of close to 30MB, I'm at about the limit I can take this model to, for now. Depending on hardware and software improvements I can make as time goes on, I'll come back to this one, to add more detail.