NOTES FROM THE ARMOURY
The most commonly used standard fixed machine guns in German aircraft during the First World War were simply adaptions and developments of the German army MG 08. Andy Saunders describes the weapons and their usage.
The principal aerial machine gun of the German air service during the First World War was based around various adaptations of the army’s land-based MG 08. Andy Saunders details its use in the air.
During the Second World War, the mounting of machine guns and cannon in wings of fighter aircraft was the norm, the airframe structures designed specifically to accommodate them. It was, however, a different story in the First World War. Then, the relatively flimsy design of aircraft precluded any installation of weaponry in such a fashion. However, when fighting in the air developed across the first year of the war, so the question arose for all combatant nations: what weaponry could be utilised?
Aside from initial attempts to fire at opposing aircraft with revolvers or even rifles, there seemed little in the way of other suitable weaponry. Apart from those machine guns which could be flexibly mounted in cockpits and were clear of propellers, then there was initially little opportunity to mount fixed machine guns in aircraft. Quite apart from the question of weight and of cooling, it was clearly impossible to mount forward-firing machine guns. And while wing structures would not bear the weight of guns and ammunition, any such weapons mounted on the fuselage would simply shoot away the propeller blades!
All of that changed, of course, with the design and development of the interrupter gear – an ingenious mechanical device which literally interrupted the firing of the guns when a propeller blade was directly in front of the gun muzzle. Finally, it had become possible to fire through the propeller arc. It was nothing short of revolutionary.
Whilst the story of the interrupter gear is not the focus of this article, it is important to briefly examine its background when considering the German use of MG 08 variants in the air.
THE GAME CHANGER
The first reliable interrupter gear was devised by Anthony Fokker, but doubt has often been cast as to origins of the design. It is certainly the case that the French introduced a device ahead of Germany allowing bullets to be fired through the propeller arc. Nevertheless, this was relatively rudimentary and was also reliant on steel plates on the propeller blades to deflect rounds that fired at the wrong time. This piece of apparatus first fell into German hands when a French aircraft was brought down and captured, the equipment subjected to investigation by Idflieg. It was then passed to Anthony Fokker for examination, although a similar device was apparently already under development by Fokker, working with engineer Heinrich Lübbe.
Ultimately, Fokker’s gear was introduced during the early summer of 1915 on the Fokker Eindecker and almost immediately it became a game changer.
The equipment resulted in the first victory on 1 July when Leutnant Kurt Wintgens, of Feldflieger Abteilung 6b, flying a Parabellum-armed Fokker M.5K/MG, forced down a French Morane Saulnier east of Lunéville. However, it had also been a Morane Saulnier, flown by French aviator Roland Garros, who achieved the first interrupter gear assisted victory on 1 April 1915. Ironically, it was also Garros’
Morane which fell into German hands later that month, providing Fokker with a specimen of the French equipment.
With the problem of firing directly ahead from the fuselage now solved, the way was opened-up for single-seat aircraft to be employed specifically for hunting down and destroying enemy aircraft. The fighter aircraft had properly been born.
However, if the problem of firing through propeller arcs had been solved, there remained the question as to which weaponry to employ. Quite simply, the pre-war years barely envisaged the use of aircraft for military purposes let alone the arming of them. Thus, with no bespoke aerial machine gun available to any of the warring powers on the outbreak of war, it became necessary to modify and adapt that which was available: ground weaponry.
ENTER THE MG 08
As aerial warfare developed, so the warring nations drew upon those existing machine guns to satisfy the need for an aerial machine gun. For Germany, the MG 08 was one of the ground weapons to which it turned, and although other weapons were available, it was the MG 08 that would become the basis of one of the main fixed machine guns for German aircraft of the First World War.
The weapon had been in service with the German army since 1908 (thus the ‘O8’ in its designation – a truncated year of implementation being standard in the nomenclature of German weapons) and had been developed from Hiram Maxim’s invention of the late 1800s, progressing on through the MG 99 and MG 01 to the MG 08.
By the start of the conflict in 1914, Germany had some 4,411 MG 08s in service and, thereafter, production was stepped-up to meet the demands of war. The minutiae of the story behind the land-based MG 08 will be covered in a later issue of Iron Cross magazine, however.
Looking at the MG 08 to develop as a potential aerial machine gun, it was apparent that the jacketed water-cooling system was simply inappropriate for use in aircraft. However, the ‘problem’ pretty much solved itself. After all, if these weapons were mounted on the fuselages of aircraft then the slipstream from propellers, and the forward motion of the aircraft, would solve the barrel
cooling problem. In essence, all that was done in the development of the MG 08 for aerial usage was to remove the water jacket and replace it with an open-slotted sleeve allowing the rushing air to circulate around the barrel.
THE IMG 08
The first version for air use was the IMG 08, the ‘I’ meaning luftgekuhlt (air cooled), and not Luft (air) as the designation is often incorrectly thought to mean.
The gun was developed by the Spandau arsenal and went into production in 1915, initially used as a single mounting on the Fokker Eindecker E.I to E.III aircraft. In fact, with Spandau stamped into the gun’s fusee top cover, this led to the weapon being colloquially (and again – strictly speaking – incorrectly) known to the Allies as a ‘Spandau’.
One of the inherent constructional strengths of the MG 08, though, was the physical support provided to the barrel by the water jacket, it being found with the IMG 08 that the fourteen rows of cooling slots introduced into its jacket overweakened its structure. That is unsurprising, since some 50% of the jacket’s initial surface had been removed. Such was this weakness that the earlier versions of the IMG 08 could not be fitted with the muzzle booster due the weapon’s fragility.
This flaw was at least partially rectified in later versions of the IMG 08 with the number of slots reduced and the jacket reverting to solid metal at the breech and muzzle ends.
THE LMG 08/15
This weapon was a further development of the IMG 08, having its receiver block lightened and stepped down and the diameter of the cooling jacket reduced along with other improvements and refinements.
These modifications also lightened the weapon, although the mounting points on the new version of the gun remained unaltered. This allowed the IMG 08 guns in existing aircraft to easily be upgraded to the LMG 08/15.
Although the suffix 08/15 would indicate a 1915 version of the weapon, the gun was not introduced in service until 1917.
FITMENTS AND FEATURES
Both guns were belt fed with 500 x round fabric belts, and not only were the belts for the MG 08 made for 250 x rounds but the design for both the IMG 08 and LMG 08/15 belts differed slightly to those for the land version. As we have already seen, Manfred von Richthofen was insistent that his pilots be responsible for carefully and fastidiously loading their own ammunition belts.
Although the fired cases were ejected, the belts were retained in the aircraft and, after firing, were fed down a tube below the gun and reused. These tubes can be clearly seen on the LMG 08/15 machine guns from Manfred von Richthofen’s aircraft as they were examined after his Fokker DR.I was shot down. Also visible in these photographs are the trays which guided ejected cartridge cases.
A later refinement sometimes fitted to the gun’s backplate was a simple round counter giving a visual indication to the pilot as to how much ammunition he had left.
Because the guns were mounted ahead of the pilot, usual procedures
■ Above: For use on Zeppelins and other airships, the MG 08 was used in its original (ground) configuration, complete with water jacket. These are two MG 08 examples recovered from the wreck of Zeppelin L.33 which crashed at Wigborough, Essex, on 23/24 September 1916. They were exhibited along with two Parabellum guns.
■ Left: An Australian officer examines one of the LMG 08/15 machine guns from Manfred von Richthofen’s Fokker Dr I. In this image, the tube for the used ammunition belt and the feed trays to guide in the rounds can be clearly seen. This gun was colloquially and universally called a ‘Spandau’ by the Allies. (AWM) for clearing blockages and loading and unloading were impossible. Thus, cocking devices were implemented in the form of the ‘Klingstrom’ which allowed cocking and loading from the cockpit with one hand. Cocking handles varied in type and style, with long handled examples being the more common type later in the war.
Another unusual ‘refinement’ associated with the LMG 08/15 are deflector plates seen fitted to Hermann Göring’s Fokker D.VII (see page xx) to deflect ejected cases away from the cockpit. Göring was apparently irritated by the empty cases being flung back at him, often entering the cockpit.
Initially, sighting was through a ‘ring-and-bead’ foresight, but later developments allowed for sighting through an optical telescopic sight. Early developments of a reflector sight were made (similar in principle to the well-known Revi sight of the Second World War) with photographs existing of this type of sight on a Fokker DR.I.
Although the water-cooled MG 08 was dispensed with for aerial use, that was not always entirely so. With low airspeed and insufficient airflow to cool the barrel, Zeppelins and other airships were fitted with the standard waterjacketed MG 08 – there being no other option for cooling.
In total, 23,000 LMG 08/15s (and an unknown number of IMG 08s) were manufactured. As a weapon, they were well liked by the pilots and it is true to say that many of the victories secured by Manfred von Richthofen and his pilots fell under these guns.