Question

How to draw the Newman projection of ethene down the C=C bond?

Answer 1

Uh, I'm not sure why you would but, okay... It's not nearly as interesting as `"H"_3"C"-"CH"_3` down the `"C"-"C"` bond, so maybe you should draw that too.

---

Here is the Sawhorse projection:

And here is the resultant Newman projection from compressing it down:

So, the Newman projection is just a circle to divide what bonds are behind and what bonds are in front. Then slightly separate the rear and front `"C"-"H"` bonds to distinguish them.