How to make smooth curves and rough edges I'm currently trying to make a plane, a Short SC.7 Skyvan. 

And as you see here, on the tail, there is a smooth curved corner at the front and a sharp edge at the back. How could I do this? 

]3

I've started with a cube but I've no idea how to make that shape. Any ideas?
Here's one approach:




6-sided circle
Fill (F), and Knife cut (K) using Ctrl to hit center of edges
Drag out back edges. (Scale thinner if you like)
Add loop cuts (CtrlR). Assuming you might want to bend the aerofoil.
Extrude (E) perimeter edges
Maybe pull out the middle edges of the side? and put in a holding edge-loop (CtrlR).
Add a Mirror modifier,
And a Subsurf modifier.