Hi Robert, you can avoid the deformation if you use the "Rigid" option in Flow. It's a checkbox that appears in the command options area in the upper right area of the main window when you are running the Flow command.

But if you want to have no deformation it may be better to use Array along curve and initially only create the large rib piece and not the smaller pieces that were inset in your video. So something like this:



Then instead of creating the smaller radius pieces directly on the rib, instead make a tube. To do that draw in a circle at the base of the same path curve, then select the circle and run Construct > Sweep to build a sweep surface:




Having that continuous longer tube be used instead of little nubs on each individual piece will not have any gaps:



If your goal is to render this, you can just be done here, there isn't really any need to boolean the pieces together.

Hope this helps,
- Michael