Is it possible to flatten out a curved curface?

I have a model that looks like half of a pipe, but isn't perfectly round and gets larger as the length increases.  I have attached a picture of it, and I am focusing just on the pipe section, not the outside caps.  I was wondering if there is a feature that will allow me to flatten it out so that I would be able to measure the length accross the curved surface?  The way they build the model is by cutting a flat piece of plastice and rolling it up to form the curve.  It might would be easier to just measure the inside curve at a few locations and them sketch it out using the spline feature.  Any advice would be appreciated.

SolidworksPlastics And Mold Design