Projection Turns Line Into Spline

[c.d.pass]

I can not figure out why a line turns into a spline after performing a projection. 

1) Select Create Sketch and picked the front surface of the Duct. (Sketch33)

2) Select Project and choose the outside edge of the profile.

When I delete the Projection symbol the projected line turn into a Control Point Spline. I am expecting the projected lines to turn into non-projected sketch lines and arcs. Because the sketch was created on the Duct's front surface all the lines should be in a single plane which would not result in a spline. What am I missing?

[laughingcreek · Accepted solution]

try this-

[jeff_strater · Accepted solution]

Those edges are not linear, that's why the projection is not a line.  You can tell this by trying to put a work axis through those edges:

Those edges are generated by Loft2.  Loft is not guaranteed to create linear edges, even if the source sketch contains lines.

You can get to where you want to be by projecting the geometry from the source sketch "duct front":