The actual shape of the later Bf 109Gs and Bf 109K is missed in the earlier Heinz J. Nowarra work "Messerschmitt Bf 109" and fictionalized in William Green's later "Augsburg Eagle", in particular Messerschmitt's clumsy installation of the 13mm MG. 131 machine guns in the Bf 109G-5 and later variants.
The "Milestone" is recognizing "the troublesome bulges at the rear of the cowling had been eliminated by some skillful redesign work." See pages 42, 45 and 58.
This the earliest mention of this feature that I am aware of.
Thank you, Jim Craig.
