How to scale objects along the length of a curve and keep them all facing the same way

I have created a long capsule shape and I want a large number of arches to be spaced along it. The capsule shape bends along both the y and z axis, but all the arches should be aligned to the x axis with no rotation.

With dupliframes I got them to follow the shape of the capsule, but because it bends, while they are all oriented along the x axis, they weren't as wide as they should be at the far end. It doesn't seem to be a tool where I can add something on to also scale the x axis of the arches further along the curve. With an array modifier set to fit curve they turn to align with the curve.In that setup I could use an empty to scale the ones further down, but only if the arches can be made to align the right way.

The arches should align with the green highlighted arches. Is there a way to do this? Otherwise I think I'll break the curve into sections and create an arch with the right dimensions for each one, and an array for each. The structure is very large, there will be something like 600 arches, so it makes a difference.

• could you include the x, y, z axis? – Faceb Faceb Nov 26 '16 at 22:42
• @FacebFaceb how do you mean, get the object to show it's axis orientations? I rarely use that, tried turning it on but i must be doing it wrong... – kim holder Nov 26 '16 at 23:14
• Yeah, i've turned on Object >Display > Axis, and it's doing squat. Is it important? – kim holder Nov 26 '16 at 23:24

As far as I know you will either be able to scale them progressively or orient them correctly at once, not both.

Using the arch as duplifaces in an arrayed plane you get correct orientation always facing one axis but no scaling.

You can then make duplicates real and clear any erroneous rotations introduced by the curve modifier.

Then scale them by hand or using proportional edit as desired.

Otherwise use the the array directly on the arches. It will not orient them correctly, but you can control scaling point buy point through the curve radius property.

• Okay, i was afraid of that. This is a good clear explanation of the two methods, i'm sure it will be useful to others. – kim holder Nov 27 '16 at 4:22

What you could do is use the curve, set curve twist to tangent, give the curve depth in geometry, and use alt s to scale the curve radius. This gives you arches facing all the same direction and variable control over its thickness.