Bulgarian antiaircraft machine-guns
As well as the guns, also the machine guns were employed, at first temporarily, in anti-aircraft defence. They could not be regarded as a good replacement for guns, but they were considered effective against low flying aircrafts. To this aim in October 1915 the Bulgarian Air Defence raised the first unit armed with machine-guns. During the War the strength of this branch of the Air Defence rose from seven machine guns to five MG half companies (картечна полурота).
The Bulgarian army used Hotchkiss, Madsen, Maxim and Schwarzlose machine-guns. Once more the problem was to adapt them for anti-aircraft work. From the beginning the 2 Hotchkiss and the existing 5 Madsen machine guns were put on special mounts. During the war the Madsen machine guns were usually mounted on special pedestal (see the picture), while the Maxims were removed from their carriages and put on basements, like the German 1916-pattern tripod with a/a adaptor.
The Maxims used also the so called Doppellafette (double carriage), a simple device, assigned in great number to the German a/a units. It was composed by a circular support that could be fixed on a wooden pole, where a carriage composed by two parallel cheeks with hinged brackets could rotate freely. The axis placed near the pivot limited the overthrowing, and was used only to fire at ground targets, while the second axis, put outside, allowed great elevation angles, and was used to fire against aircrafts. However the Bulgarian Army employed also a great number of improvised mountings.
In order to
improve their performances Schwarzlose and Maxim machine guns received also a
special circular sight. They were made up of two metal rings with a radius of
65mm and 46mm respectively, that were attached perpendicularly to the barrel
of the machine gun at a line of sight of 900mm. With this apparatus the fire
was effective against aircraft flying at a speed of
Later the Head Quarters of the Air Defence proposed an improved model of circular sight, which was designed in order to stay horizontally for every kind of declination. The circle had a radius of 70mm and 16 silhouettes were engraved on it, representing aircrafts flying at different flight angle. The line of sight was 900mm.