If this has been discussed before , sorry for re posting , but I couldn't find anything through the search function so....
I am wondering if there is a difference if the drag is on a horizontal surface say like a wing , opposed to a verticle surface like the side of the fuse...excluding argument of the surface area of the two examples I have mentioned.

I want to make a cowl that encloses my engine and pipe.. and want to know if there is a difference if I just make the cowl a flat surface over the top of the engine and pipe or mold it to more of a knife edge