Big Smooth Banked Curve?

I want a perfectly smooth banked curve - bigger than can be made with one prim - and trying to make one is making my brain hurt at the moment.

Anybody able and willing to explain how?

Follow my tutorial on making large circles and you'll be half way there. Once you've got the circle, skew the tops inward, and you've got your banked curve. To make it as seamless as possible, you may also want to shrink the tops, but be careful. If you overdo it, you'll mess up the curvature.

Note, by the way, that if you follow the tutorial to the letter you'll have V-shaped grooves between the sections. That tutorial is pretty old, and I've since refined the technique to eliminate those grooves without having to use extra prims. Simply make the sections a little bigger, and overlap them. Because of the curvature of the clindrical pieces, you can avoid flickers or any other noticeable sign of overlap if you take care to align them just right. It takes a little time to get the first two right, but once you've got those, you've got the whole thing. Just rinse and repeat all the way around.

To see a good example of this, check out the corridor walls inside my USS Defiant. Especially, take a look at the outer wall surrounding outer ring of rooms on deck 2 (sickbay, mess hall, etc.) It's hard to tell from within in the rooms, but if you fly the camera out behind the wall, you can follow it all the way around and see that it's one totally seamless circle, about 80M across.

I'll have a new tutorial written for exactly how I did it sonner or later, but in the mean time, just take a look the linked parts and I'm sure you'll figure it out. If you've got any specific quesion's let me know.

Also, it's funny you should mention banked curves, because those very rooms I mentioned in the Defiant are supposed to have one on that very same wall. I just never got around to finishing that part yet. Skewing the tops of the cylindrical pieces was precisely how I was planning on doing it.