The German arsenal

German plans for air-fighting and aircraft armament went through a dramatic series of changes from the mid-1930s to the end of the Second World War, and resulted in a far greater variety of weapon projects than in any other nation, although many of the most technically interesting were still under development at the end of the war.

While Germany was among the first to introduce one of the new breed of monoplane fighters with retractable undercarriage and enclosed cockpits (the Messerschmitt Bf 109), they were not as far-sighted as the British in specifying the armament. At first, the fledgling Luftwaffe was strongly influenced by French thinking about aircraft armament. This included the concept of long-range fire using a single, powerful automatic cannon mounted between the cylinder blocks of a vee-configuration engine, firing through the hollow propeller hub and thereby avoiding all the complications of synchronisation. This layout kept the weight of the weapon and ammunition close to the centre of gravity, to the benefit of aircraft agility.

The French had selected the most powerful of the Oerlikon designs, the FFS, but when the Luftwaffe tested it they found a problem: the maximum diameter of gun which could pass between the cylinder blocks of the German engines was only about 70mm. The FFS was wider than this because all Oerlikon aircraft guns had the main recoil spring wrapped around the barrel and connected to the bolt by a substantial yoke. It simply would not fit. There were other concerns to do with reliability, which was very dependent on the quality of the recoil spring.

Faced with these problems, the Luftwaffe took three decisions. In the short term, RCMGs would be used (the 7.9mm MG 17). The Messerschmitt Bf 109 originally carried just two, cowling-mounted and synchronised. The Bf 109B added a third engine-mounted one. In the long term, Mauser was given the contract to develop a new high-powered and fast-firing gun which would fit; this became the MG 151. For the medium term, Rheinmetall-Borsig produced the formidable MG C/30L, related to their 2cm FlaK 30 anti-aircraft cannon.

The MG C/30L fired the massive 20X 138B 'long Solothurn" cartridge, one of the most powerful ever used in a 20mm aircraft gun. The already high muzzle velocity of the FlaK 30 was further improved by the fitting of a longer barrel, intended to extend beyond the propeller hub. The usual twenty-round box magazines were replaced by a

100-round drum, mounted rather unusually under- synchronised RCMGs. Later models reverted to the neath the gun. Plans were made in 1936 to equip a original plan of one engine-mounted cannon and prototype Bf 109 and its rival He 112 with this gun two RCMGs, a very light armament which typified in place of the usual twin machine guns. At least most Bf 109 variants in the early years of the war.

one of the He 112 prototypes, known as the The engine-mounted version of the MG-FF, briefly

Kanonenvogel (cannon bird), was so equipped and used in an early model of the Bf 109F before being sent for evaluation to the Spanish Civil War, where replaced by the MG 151, was a standard gun with it saw action before being destroyed in a crash-land- the minor addition of a mounting ring clamped to the barrel to enable it to be fixed in place relative to the blast tube. The Bf 110 at this time carried two MG-FFs and four RCMGs in the nose, and most ing in July 1937.

Although the MG C/30L was officially adopted for service (and was renamed the MG 102 in 1942), the Luftwaffe had a change of heart after only 180 radial-engined Focke-Wulf Fw 190s carried two of the big Rheinmetall guns had been made. The MG-FFs in the wings as well as two MG 151s, and main reason for this appears to have been the mas- two RCMGs in the cowling.

sive weight of the installation (reported to be

The Ikaria cannon was a successful weapon lim-

around 180kg including ammunition), but there ited by a low rate of fire, low muzzle velocity and (in were also concerns about the strain on the weapon most applications) a small magazine capacity. Like caused by the weight of the barrel and the animu- most of the other Oerlikon-pattern guns, it could nition transport, and in the insufficient reserve of not be speeded up to achieve more than 520-540

recoil power to operate the weapon reliably. The big rpm because of the weight of the yoke connecting guns saw limited service on the ground in the AA the spring to the bolt, which could not be reduced role, but fitted with shorter barrels.

for fear of weakening the mechanism. In fixed

This left the Luftwaffe with a problem. They had mountings, the yoke and spring were exposed, learned that the new British fighters were to be Flexibly mounted guns had a quite different equipped with an impressive eight-gun wing- appearance, with a bulbous barrel casing, extending mounted armament, which the little Bf 109 had almost to the muzzle, covering the reciprocating never been designed to carry. In the short term two additional RCMGs were fitted to the wings, but more powerful weapons were clearly needed. At this time, the MG 151 was years away from production, so the Germans sought an interim solution in the smallest of the Oerlikon guns, the FF, which was able to fit the engine mounting.

Trials of the gun were satisfactory, except for some magazine feeding problems. It seems that the engine mounting was not considered successful at that time as the much higher operating temperatures caused reliability problems. At the parts in order to avoid the gunners' fingers or other loose items becoming entangled with the mechanism. They were also equipped with side-mounted grips and a distinctively curved shoulder stock.

The low muzzle velocity limited effective range, as it magnified any errors in estimating distance or deflection angle. This was not helped by the different ballistics of the 7.9mm and 20mm ammunition, which made using the smaller guns as 'sighters' problematic. The 7.9mm had a higher muzzle velocity, a shorter time of flight and a flatter trajectory, which could be compensated for only at a particu-

urging of Udet, the head of the LC Air Technical lar range and when firing at zero deflection; at

Office of the RLM (Reichsluftfahrtministerium, or other ranges, or against manoeuvring targets

German Air Ministry) and an outspoken advocate requiring deflection shooting, projectiles from both of close-range fighter tactics, the FF was selected calibres of gun were unlikely to strike the target for wing mounting. After considerable modification simultaneously.

and production by Ikaria Werke-Berlin, the result-

The MG-FF s usual sixty-round drum feed also ing MG-FF, along with RCMGs, equipped almost limited its combat persistence, although a compact all German fighters in 1940.

Most Bf 109Es in service in the Battle of Britain carried two MG-FFs in the wings plus two drum for flexible mountings. The mechanism was ninety-round drum, the T 90-FF, was introduced much later, as well as a very small thirty-round

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