It's a nice close approximation.

But note that each 3 point arc that you draw is a planar curve, so the resulting shape has each 90 degree chunk in a separate plane - this is slightly different than a true helix which has a more gradual progression through 3D space instead of in planar pieces.

It looks very nice though, and the end tangents are very close between pieces - looks like only about 0.1 degrees deviation.

- Michael