gun synchronization to fire through propeller arc

[kolya1]

Originally Posted by Graham Boak

I suspect there were biplane fighters with 4 fuselage-mounted machine guns, although I can't think of one offhand. The Me 209-II had a similar wingroot mounting to the Fw series. The La 7 is nagging at me - there were versions with three cannon in the fuselage and others with either two or four. My books are temporarily out of reach.

Yes, there were effectively some biplane fighters with 4 guns firing through the propeller's arc : I can think of the Polikarpov biplanes : I-15, I-15bis, and I-153. The early models had PV-1 MGs while the late ones used ShKAS, which must have been quite difficult to synchronise, because of their very high rate of fire (1800 rounds/min unsynchronised). The MiG-3 also usually carried 3 guns in the nose above the engine (2 ShKAS, 1 UB). The La-7 had usually 2 ShVAK 20mm guns, but by the end of the war versions with 3 lighter B-20 guns appeared. The post-war La-9 and La-11 had 4 NS-23 23mm guns.

I don't know if that is among the reasons why some air forces favored wing guns and other fuselage ones, but I think I once read that Soviet pilots who fired at close range complained about the disposition of the Spitfire's armament. I suppose it's possible that air forces that emphasized deflection shooting preferred wing guns which covered a wider area...