# Unfolding A Curve

#### chally72

##### New member
We have a 2d sketch of an airfoil section. For in-process verification, we need to be able to check the part in the flat state. (These airfoils are formed from a flat blank.)

How can I straighten a curve in SE while keeping its length the same? Will I be able to maintain a relationship between the curve and a specific point on the curve, so as to repeat this unwrap "around" the same point through multiple sections?

Thanks to anyone who can help with any part of this.

#### Haag_Enterprises_LLC

##### New member
Can you reply with a screen shot of the curve you're wanting to unfold please?

Thanks,

David Haag, M.E.

#### chally72

##### New member
Wow, a reply on Thanksgiving!? Hope you took some time to enjoy the turkey, too.

I'm having trouble attaching some rough sketches here, but I'll try to explain it. I came up with a better way of doing this, I think.

Picture an airfoil cross-section with a bunch of cut lines perpendicular to the concave curve of the blade. Say, 20 or so cuts between the leading and trailing edge. If I can measure the length of the curve in between these cut lines, and knowing the length of each cut line, I can "unfold" the concave side of the blade to make it flat by drawing flat sections the length of each curve section, with cut lines off of each, and then regenerate the convex side as a curve through the tip of all the cut lines.

The problem I have is that the only way I can find of measuring the length of a curve is the Total Length inspection option, which only displays the length until you click off of it. Meaning I can't use it in goal seek, and I can't even display more than one arc length at a time. If I could use it in goal seek, for example, it would be simple to make a canned flat-section generator that I could drop any airfoil section into and relatively quickly "unfold."

Thanks!

#### Solid DNA

##### New member
chally72

Not sure in can picture the use of the goal seek command to create an unfold representation?

Have you try to use the contextual menu of the curve (RMB then select properties). you will have a total length properties.

If you are looking at a cross section of the airfoil, create a draft, create a section, then convert the section into a 2D view.

Use the contextual menu of the view to select "draw" in view. RMB on the curve to access its properties.

If you need only a portion of the curve, use the split tool