I’m sure that everyone is aware of the Messerschmitt Bf-109 series of aircraft. The F model entered production in November, 1940 and differed from the previous “E” models by using a more powerful version of the DB 601 engine and featuring a more streamlined nose cowling. Armament consisted of two nose mounted machine guns and a cannon shooting through the engine crankshaft. Many of Germany’s top aces preferred the F model over the earlier E or even the later G and K models. I recommend Lynn Ritger’s two books from SAM Publications for reference purposes.