I was initially going to set up this section split into the Hawk II, Hawk 3, and so forth. Problem is, the Navy used one designation, the Army another (don't forget, this is the era between the two World Wars where the Air Force didn't exist except as part of the army) and exports could use a third designation.
So, as I get the information together here, I'll be attempting to straighten things out as to who goes where, and what's comparable to what. Boeing, Curtiss' main rival, did something similar with its fighters of the time. Hopefully it won't get too confusing!