Editing Synchronization gear (section)

== Rate of fire ==
[[File:Fok Eiv cockpit.jpg|thumb|The Fokker E.IV prototype's original "three-Spandau" armament, before the portside gun was removed. Production examples had two guns, arranged symmetrically.]]

A pilot would usually only have the target in his sights for a fleeting moment, so a concentration of bullets was vital for achieving a "kill".<ref name=Williams1.16/> Even flimsy First World War aircraft often took a surprisingly large number of hits to shoot down, and later, larger aircraft were even harder propositions. There were two obvious solutions{{snd}}to fit a more efficient gun with a higher ''cyclic rate of fire'', or increase the ''number of guns'' carried.<ref group="Note">A third solution was to replace the rifle calibre weapons with heavy machine guns or cannon: for various reasons this did not become common until the 1940s.</ref> Both of these measures impinged on the question of synchronization.

Early synchronized guns of the 1915–1917 period had a rate of fire in the region of 400 rounds per minute. At this comparatively leisurely rate of fire a synchronizer can be geared down to deliver a single firing impulse every two or three turns of the propeller, rendering it more reliable without unduly slowing the rate of fire. To control a faster gun, with, for example, a cyclic rate of 800 or 1,000 rounds a minute, it was necessary to supply at least one impulse (if not two) for every rotation of the propeller, making it more liable to failure. The intricate mechanism of a mechanical linkage system, especially of the "push rod" type, could easily shake itself to pieces when driven at this rate.

The final version of the Fokker Eindecker, the [[Fokker E.IV]], came with two [[Maschinengewehr 08#Aircraft versions|lMG 08 "Spandau" machine guns]];<ref name=Grosz1>Grosz 1996, p. 1.</ref> this armament became standard for all the [[Idflieg aircraft designation system|German D-type scouts]] starting with the [[Albatros D.I]].<ref group="Note">Fokker's initial armament for the first prototype E.IV was in fact ''three'' machine guns but simply mounting three "followers" on the single cam wheel of the early ''Stangensteuerung'' gear proved quite unworkable, and production examples carried only two guns.</ref> From the appearance of the [[Sopwith Camel]] and the [[SPAD S.XIII]] in mid-1917, right through to the end of gun synchronization in the 1950s, a twin gun installation was the international norm. Having the two guns firing simultaneously would obviously not have been a satisfactory arrangement. The guns needed to both fire ''at the same point on the propeller disc'', which means that one had to fire a tiny fraction of a second later than the other. This is why early gears designed for a single machine gun needed to be modified in order to control two guns satisfactorily. In practice, at least part of the mechanism had to be duplicated, even if the two weapons were not synchronized separately.