From 1918 to the mid-1930s the standard armament for a fighter aircraft remained two synchronized rifle-calibre machine guns, firing forward through the arc of the propeller.

Did old war planes shoot through propellers?

Machine guns were mounted on the top of the fuselage, directly in front of the pilot, but that position placed the gun directly behind the propeller. ... The gun had to be designed to fire through the propeller without hitting it, which was not an easy task.

Who invented shooting through propellers?

One early method of doing this was invented by none other than Roland Garros, who in December 1914 had the propeller of his Morane-Saulnier Type L monoplane fitted with metal wedges to deflect stray bullets.