parametric settings of objects that follow the arc to change the radius

[jim78b]

save place the image of the work that I have to do, in practical design crates for galleries, where there is the arrow and a omega or a folded sheet that at the varying radius of the white sheet is concentric but how do I with the parametric to set that if I change radius these omega precisely follow the radius of the sheet?
I mean, I want to do something that when I change the radius, I don't shake everything.

 

[Joseph]

If you had 2012 you could use the command "series along a trajectory".