Is there a way to use an arc length of a revolved edge as a global variable?  I have tried adding a global variable in the Equation Editor using the "Measure" option and selecting the end points and the arc as I would to dimension it on a drawing, but all I get is the chord length (i.e. distance between the points) or the radius, depending on what order I select them in.  It seems like it only recognizes the first two clicks.  I have also tried creating a sensor from the Arc Length displayed in the regular measurement tool, but it seems you can't use a sensor in an equation, which is what I'm ultimately after.

What I'm really trying to do is measure the arc length of a curved part and then use that value to define the length of the flattened configuration in the same part.

Using SW 2016.  We don't have the flattening tool... yet...