Weapons For Ai Fi Ii Tiiv

Solothurn Machine Gun

2cm MG-FFfor flexible mounting; note the barrel casing, handgrips and shoulder stock (BuOnt. VSN)

Weapon Heavy Machine Gun

2cm MG-FFfor flexible mounting; note the barrel casing, handgrips and shoulder stock (BuOnt. VSN)

not suitable for driving a belt feed, but a complex electrically driven belt feed (GZ 1-FF, or

It is worth commenting on the Schräge Musik installation. There were basically three reasons for

Gurtzufiihrer 1-FF) was developed. It was mainly fitting guns in such a way. First, the RAFs night used in some night fighters and was capable of deal- bombers were generally easier to see from below, with their full planform silhouetted against the night sky. Secondly, the night-fighters were less easy to spot from above, against the dark ground. Thirdly, unlike most Luftwaffe and USAAF

ing with an astonishing 2,000-round capacity -enough for nearly four minutes* continuous firing!

Despite its limitations, the MG-FF survived in service until the end of the war. Its light weight made it popular for flexible mountings, and also for bombers, few RAF aircraft were fitted with any wing mounting as it minimised the impact on downward-firing guns or even observation win-

agility, which was presumably why most early dows, so the fighters could creep close underneath

Focke-Wulf Fw 190s had two MG-FF in the wings them for an easy shot. On the other hand, some to supplement the inboard MG 151. The inherently night-fighters were brought down by the falling air-

recoil-absorbing nature of the mechanism also craft they had just attacked. The Germans estimat-

meant that simple mountings could be used (in con- ed that in 1943 and 1944 about 80% of night-fight-

trast, the MG 151 had to be mounted to allow er successes were achieved with Schrage Musik about 18mm of recoil movement). The Ikaria gun guns.

remained longest in night fighters and latterly in an

Tracer ammunition was not used in upward-fir-

upward-firing 'Schräge Musik' (oblique or jazz ing guns to avoid alerting the bomber crew, and it music) installation in aircraft such as the Bf 110G- took a long time for the RAF to realise that the 4/R3, in which its compactness was more important Luftwaffe was using this technique. This is rather than its low muzzle velocity.

surprising, given that the British experience with upward-firing guns in the First World War had continued with the inter-war COW gun fighters and with early wartime experiments with upward-firing guns in a Blenheim (replacing the turret) and a Havoc (Douglas DB-7). It appears that British interest in such installations faded early in the war, with the introduction of AI (air interception) radar, which favoured a rear approach. Once the news broke, some bomber units fitted downward-firing guns and the H2S ground-mapping radar was adapted to spot aircraft flying underneath the bomber. The technical battle between bombers and night-fighters was intense and ever-evolving, but further comment is beyond the scope of this book.

Rheinmetall-Borsig were not discouraged by the failure of their MG C/30L and set about producing two other air-fighting cannon: the 2cm MG 204 and 3cm MK 101. In addition, their Swiss subsidiary Solothurn introduced an aircraft version of the SI8-100 anti-tank rifle known as the SI8-350. This was fitted in a flexible mounting in the nose of the Fokker T.V bomber in Dutch service, but it retained its semi-automatic mechanism and was not considered successful. By the beginning of the war the MG 204 (initially known as the Lb 204) was in limited service in some Luftwaffe seaplanes: the Do 18E, Bv 138A-1 and the ex-Dutch Do 24K-2. Two different ammunition types were used: initially the same belted 20 x 105B (the 'short Solothurn') used in the SI8-350, later a modified beltless version in an attempt to improve its dubious reliability. As it was intended for flexible mounting, in which role it must have been a handful, it was fed by a 20-round saddle-type drum magazine. Belt-fed and 100-round drum versions for fixed mounting were developed but not adopted. The gun was too heavy and too slow-firing to be a success.

The MK 101, a much larger cannon, was developed before the war as a long-range bomber-destroying gun for fitting to twin-engined aircraft such as the Bf 110. This massive weapon was designed around a new high-velocity 30 X184B cartridge. It saw action during the Battle of Britain, one shot-down Bf 110C-6 being found to have an externally mounted MK 101 instead of the usual pair of MG-FFs. It was also fitted experimentally to a Dornier Do 24T flying boat and to a dozen

Heinkel He 177A-1, intended as Zerstórer (bomber destroyers), in a steerable under-nose twin turret, the Lafette LI01/1 A. This big-gun concept was overtaken by the switch to the MG-FF, although the MK 101 later found a different and much more productive purpose in the anti-tank role, carried by the Henschel Hs 129B-1/R2.

A lot of other experimental work was carried out in Germany during the inter-war period, resulting in prototypes of gas-operated 2cm cannon by Lubbe and Krieghoff, neither of which was accepted. Instead, the German aircraft cannon and heavy machine guns which eventually replaced the rifle-calibre guns and the MG-FF during the Second World War became dominated by the designs of Mauser (in 15mm and 20mm calibre) and Rheinmetall-Borsig (in 13mm and 30mm).

Incidentally, the Germans used two different forms of aircraft gun nomenclature. Until 1942, the first number of the designation indicated the calibre, the next the gun model (e.g. the MG 131 was the first model of 13mm gun). After that date, the system was changed so that the first of the three numbers indicated the design firm (1 = Rheinmetall-Borsig, 2 = Mauser, 3 = Krieghoff, 4 = Krupp) with the next two identifying the model of gun. This system was not always applied, the MG-FF being the most obvious exception. There is also a minor mystery over the MK 101 designation, which complies with the post-1942 system; when initially used in the early part of the war, it should strictly have been called the MK 301, but this does not appear to have been the case.

The development of the wartime guns followed four priorities. First was the replacement of the MG-FF. This need was met by the Mauser MG 151. Next came a replacement for the RCMGs, which needed to be as compact as possible so that it could still be fitted into the restricted space within the engine cowlings of existing fighters; this led to the little Rheinmetall-Borsig MG 131. However, RCMGs, in the form of the compact and fast-firing MG 81 (often found in a twin flexible mounting) did remain in service throughout the war. Much later came a requirement for heavy cannon of 3cm and upwards in order to tackle the large four-engined bombers which were beginning to pound Germany. There was also a need for heavy, high-


velocity cannon for airborne anti-tank purposes, and several of the large guns were developed to meet both purposes. Finally came a variety of attempts to improve the rate of fire, culminating in the Mauser MG 213C revolver cannon.

The MG 151 was first developed in 15 x 96 calibre, and in this form was considerably more powerful than any other aircraft HMG to see service. It was a contemporary of the 20mm Hispano, being developed in the mid-1930s, and fired a cartridge with a high-capacity case which was coincidentally virtually the same diameter as the Hispano s. As with all the later German aircraft guns, the MG 151 was available with electric priming to facilitate synchronisation (this version was sometimes referred to as the MG 151E), although percussion-primed versions were developed first. The 15mm gun was first fitted to the Bf 109F-2 in 1941 and was also used in a few other installations such as the nose mounting in the He 115C-1.

The MG 151 saw relatively little service in its original 15mm form. Wartime experience revealed that a larger explosive shell was more valuable than very high velocity, so the MG 151 cartridge case was 'necked out* and shortened (to preserve the same overall cartridge length with the longer 20mm projectiles) to 20 x 82, thus creating the MG 151/20. Projectile weight increased at the expense of muzzle velocity, but the gun weight and rate of fire of around 700 rpm remained the same. The armour penetration of the AP shot fell from 18mm/ 300m/60° to about 10-12mm, which was just about adequate to defeat aircraft armour. The gun retained the option of electrical priming and one of its first applications, the Focke-Wulf 190A, featured synchronised MG 151 /20s in the wing roots.

The Bf 109 retained percussion-primed MG 151s throughout (the 20mm version being engine-mounted in the 109F-4 onwards), initially because the electrically primed versions were required for the Fw 190, later to avoid confusion over which type of ammunition was required. This consideration also complicated an abortive proposal to fit the Bf 109G-4 with an additional MG 151/20 in an underfuselage gondola, with far lower weight, drag and handling penalties than the two underwing gondola installation. The gun would have had to be synchronised and therefore needed to be electrical ly primed, as the percussion-primed versions were not developed for this.

The Mauser was not particularly light, powerful or fast-firing but it was a sound design which rapidly became the most important Luftwaffe cannon of the war. It equipped most fighters and some bombers (latterly in the neat HD 151 single turret), was used in some Schräge Musik installations in heavy night-fighters such as the Ju 88, was also the principal Italian aircraft cannon and even saw some Japanese service. It is commonly reported that the gun was used in cowling-mounted synchronised installations in some German fighters, but it appears that this was only planned for the Focke-Wulf Ta 152C and Dornier Do 335, both of which were too late to see service.

The MG 151 was always belt-fed. Some wing-mounted installations on a few versions of the Messerschmitt Bf 109 appeared to be pan-fed, as the 135 rounds were arranged in three layers in a circular magazine, with the noses pointing inwards. However, the "pan' was simply an unusual container for a conventional belt, which was capable of being curved in a circle. The reason for this curious arrangement was presumably to provide a reasonably shallow magazine in order to minimise aerodynamic drag.

The compact dimensions required of the MG 131, which replaced rifle-calibre machine guns in many bombers as well as fighters, dictated a small (13 x 64B) cartridge of modest power, resulting in a gun which weighed only 17kg yet could fire at 900 rpm. Armour penetration of the AP projectile was barely adequate at 10mm/100m/60°, and this fell to 7-8mm at 300m. By comparison, the best of the 7.92 x 57 AP loadings for the MG 17, the special high-velocity S.m.K-v (Spitzgeschoss mit Stahlkern-verhesserte, or improved pointed steel-cored bullet) could penetrate 8mm/100m/60° and 6mm/

As a defensive weapon the MG 131 started to replace the MG 15 in flexible mountings from 1941, in which form it was fitted with a pistol grip and conventional trigger. It was also installed in a neat, low-profile powered turret fitted, for example, to the cockpit roof of the Ju 188 and the rear dorsal position of the He 177. Twin and quadruple turrets were developed but these saw little or no use.

Remotely-controlled barbettes were used; a twin version was fitted in the forward dorsal position of the He 177, and two single barbettes were attached to the sides of the rear fuselage of the Me 210 and 410. Aimed by a gunner mounted in the cockpit, these could train up, down or to one side (although in the last case, obviously only one gun could fire at a time). Replacement of the synchronised MG 17 in fighter applications was surprisingly slow, the MG 131 first emerging in 1943 in the Bf 109 G-6 and later in the same year in the Fw 190A-7, both of which had two in cowling-mounted synchronised installations.

In an attempt to increase the destructive power of their cannon, German technicians developed a high-capacity 'mine* HE shell known as the Minengeschoss or M-Geschoss. This was manufactured by stamping out a thin-walled shell casing using the same technology used to make cartridge cases, instead of drilling out a solid projectile. The result was much more space for explosives and a much lighter weight, which also allowed a significant increase in muzzle velocity. The disadvantage was that the M-Geschoss was relatively ineffective against armour (no doubt accounting for RAF criticism of this aspect of its performance during the Battle of Britain), but this was evidently considered an acceptable trade-off for the greatly increased blast effect.

First to benefit from the mine shells was the MG-FF. The initial version was designed to use ammunition which fired 134g projectiles. In mid-1940 the 90-92g M-Geschoss was introduced, together with conventional 115-117g HE/T projectiles (apparently used because they were better suited to carrying tracer elements). The 115g projectiles were similar to the 134g but used light alloy instead of brass fuze bodies, and the velocity was reduced to match the momentum of the M-Geschoss in the interests of consistent gun functioning. These new cartridges generated less recoil than the 134g loading and required the gun mechanism to be slightly modified to compensate (with a lighter reciprocating mass and a weaker return spring), leading to the designation MG-FFM (or FF/M). Ammunition was therefore not interchangeable between the MG-FF and MG-FFM, despite being visibly similar. The first service application of the FFM appears to have been in the Bf 109E-4, introduced in May 1940. Existing MG-FFs were then converted to the MG-FFM standard, which led to the two terms being used interchangeably thereafter. The M-Geschoss technology was applied to other German aircraft cannon such as the 2cm MG 151/20, the 3cm MK 108 and MK 103, and was widely adopted post-war.

The initial magazine loads for the MG-FFM had two M-Geschoss and two HE/I tracer rounds for every APHE or API (the AP loadings being capable of penetrating over 20mm of armour at normal fighting range). In the latter part of the war the Luftwaffe stopped using AP ammunition in air-to-air combat, partly because the armoured parts of an aircraft were too small to hit very often and partly because the flight of AP projectiles was often disturbed as they passed through the skin of the aircraft so they did not strike the armour point-first. The effect of penetrating a 3mm dural plate at a 20° angle was to reduce penetration of the armour behind it by up to 30%. It was also discovered that the most effective method of destroying aircraft was by the blast and incendiary effect of HE shells detonating within the structure, so the M-Geschoss became standard. Conventional HE/I projectiles with tracers (mit Leuchtspur) remained in service and were mixed with M-Geschoss in ammunition belts. The difference in muzzle velocity, and therefore time of flight and trajectory, was evidently considered to be within acceptable margins.

As we have seen, the Luftwaffe initially favoured high-velocity cannon but later switched to lighter and faster-firing guns. Later in the war, the need for large-calibre guns emerged in order to provide sufficient lethality against heavy bombers, and two very different 3cm weapons were developed. The introduction of these weapons, whose weight had a significant effect on the dogfighting ability of the single-engined aircraft which carried them, led the Luftwaffe to develop two versions of their day fighters: heavily armed and armoured 6Sturmgruppen variants for attacking the bombers, and accompanying lighter and more agile aircraft to deal with escort fighters.

The more important of the new 3cm guns was the Rheinmetall-Borsig MK 108, a simple API blowback weapon which sacrificed muzzle velocity


103 Munition

3cm MK 108 with blast tube attached (Courtesy: MoD Put tern Room)

in the interests of destructive power, light weight and rate of fire. The Luftwaffe had calculated that it took an average of fifteen to twenty 2cm hits to down a heavy bomber, but only three or four 3cm hits. As an average only about 2% of shots fired hit their target, that meant that 750-1,000 2cm rounds had to be fired as opposed to 150-200 3cm rounds, so interest focused on the larger calibre. By comparison, Soviet calculations showed that about 150 20mm rounds were required to down a German opponent, possibly an indication that their targets were much smaller than the big Allied bombers. It is worth noting that the Germans found that only four or five 20mm hits were necessary in frontal attacks, where B-17s were relatively vulnerable, but such attacks were much more difficult to carry out.

The gun fired a low-velocity 30 x 90RB cartridge and was compact enough to be fitted to the smallest fighters, being engine-mounted in the Bf 109K-4 (and an option in the G-6 and the G-10) together with two synchronised MG 131s. The K-4 could be equipped with two more of the MK 108 underwing in a Rüstsatz (field conversion set), a modification built in to the K-6 although it appears that few if any of these saw action before the end of the war. Four of the guns were fitted to the Me 262 jet fighter and they were used to equip some Fw 190 and night-fighters. The MK 108 was also used in upward-firing Schräge Musik installations in night-fighters such as the Heinkel He 219A-7 and B-3. The gun, nicknamed 'Presslufthammer" as it looked and sounded like a pneumatic drill, was very effective but did suffer problems with the ammunition belts coming apart during violent manoeuvring -not the only aircraft gun to experience this. The pressure of war also led to its introduction in 1944, before development was complete. The original specification required 600 rpm, but an average of 650 rpm was reportedly achieved. At the end of the war, work on a modified version (referred to by one source as the MK 108A or MK 108 n A - presumably standing for neuer Art, or new type) was achieving around 900 rpm on test, but was too late to see service.

In complete contrast to the compact MK 108, Rheinmetall-Borsig also developed the MK 103 around essentially the same 30 x 184B cartridge used in the earlier MK 101, but adapted to electric rather than percussion ignition, belt- instead of clip-fed, with a hybrid gas/recoil action instead of recoil operation, and using stamped-metal parts to simplify production. The MK 103 was no lightweight at 141kg, but was nonetheless significantly smaller, lighter and faster-firing than the MK 101. The ballistic performance using M-Geschoss was slightly worse than the MK 101 because the locking mechanism was not as strong, necessitating a slight down-loading of the ammunition to avoid over-stressing the action.

From the start the MK 103, which entered production in 1943, was intended for dual anti-bomber and anti-tank roles, with appropriate ammunition developed for each. The anti-bomber round was a 330g M-Geschoss while the AP round was a tungsten-cored 355g Hartkernmunition, loaded to a higher velocity and pressure; presumably it was thought that the risk to the gun mechanism was worth taking in this case. Use of this AP ammunition lowered the rate of fire from 420 rpm to 360 rpm, because the gun mechanism unlocked more slowly as cartridge pressure increased. The gun was selected for some heavy fighters acting as bomber destroyers, including the He 219, Junkers Ju 188, various Me 410s and the experimental Me 262A-la/Ul, as well as the Do 335 and Ju 388J which were only produced at the end of the war.

Some mystery still surrounds the motor-cannon version of the MK 103, which has been referred to as the MK 103M, presumably standing for Motorlqfette, or engine-mounted. The account which follows is the most likely explanation on the basis of the somewhat fragmentary available evidence. Two different approaches appear to have been tried: a radical redesign and (possibly) a minor modification.

The radical redesign was prompted by the fact that the MK 103 could not be mounted within the standard 7cm diameter blast tube which ran through the V-12 engines. Only about 80cm of the barrel length was able to fit within the tube; the rest of the gun, 126cm long and up to 30cm wide, had to fit behind the engine, and in most aircraft (especially the Bf 109) there wasn't enough space between the engine and the cockpit. The MK 103M incorporated a modified layout which eliminated the wide barrel shroud as well as the standard muzzle brake so that the gun could be mounted further forward; a photograph exists of such a weapon, although it is not clear what changes to the operating cycle were involved. This was reportedly tested in a Bf 109 K-10 among others, but it proved unreliable and was not adopted as standard. In fact, contrary to many reports it seems clear that the Bf 109 never carried the MK 103 in action, the under-wing 3cm mountings of the Sturmgruppen versions being MK 108 only.

There is some suggestion that a simpler modification might have been developed (whether previous or subsequent to the version described above is not clear), which merely deleted the muzzle brake and modified parts of the mechanism to cope with the heavier recoil. If so, it is possible that this might have been the version fitted to the Do 335 and the Ta 152C-3, which could have had enough room in their long noses to mount the gun between the engine and the cockpit, but these emerged too late to see action.

The MK 103 proved useful in ground attack, replacing the MK 101 which had achieved a good reputation but had been out of production for some time. The Hartkernmunition was able to penetrate 75-100mm of armour at 300m, dropping to a more realistic 40-60mm when impacting at 60°. The MK 103 was fitted to the Fw 190A-5/U11, A-6/R3 and A-8/R3 ground-attack variants and to more specialist aircraft such as the Henschel Hs 129B-2. The Henschel carried one, with 100 rounds, under the fuselage while the Focke-Wulfs carried two under-wing FGB103 (Flachengondelbewaffnung) pods, each with thirty-two rounds. The pods were reportedly unsuccessful as accurate firing proved difficult. A shortage of tungsten, for which the machine tool industry had priority, limited the use of these weapons. Some reports (supported by Albert Speers memoirs) suggest that this led to the use of uranium-cored ammunition on the Eastern Front, but no physical evidence of this has been found.

An earlier gun which saw service in both the

WEAPONS FOR AIR F I ti II T 11\ (v anti-bomber and anti-tank roles was the 37mm BK 3.7, a modified version of the FlaK 18 AA gun. Armour penetration with Hartkernmunition was quoted as 70mm/100m/60° or 140mm/100m/90°.

The gun saw extensive use on the Eastern Front, fitted to such aircraft as the Henschel Hs 129B-2/R3 and Ju 88P-2 (a twin installation), and achieved particular fame when fitted, in pairs, to the Ju 87G version of the notorious Stuka (Sturzkampf-flugzeug - dive bomber). This was by far the most important of the airborne anti-tank guns and the only one authorised to retain the use of Hartkernmunition after the summer of 1944 (along with the 5cm PaK 38 anti-tank gun, which needed it to stand any chance of penetrating Soviet tanks). It was also fitted in heavy fighters such as versions of the Bf 110G-2.

These weapons were supplemented by the BK 5 and BK 7.5, modified high-velocity anti-tank guns of great power and corresponding size and weight. The Rheinmetall-Borsig BK 5 used the same 50X419R ammunition as the L/60 tank/anti-tank gun (it was basically the KwK 39 tank gun fitted with an autoloader and a twenty-two-round belt feed) which was claimed to penetrate up to 88mm armour at 250m. This might appear unimpressive in comparison with the smaller calibres but it was more reliable in that it was much less affected by the type of additional spaced armour plates on tanks which disrupted the HEAT and I fart kern rounds, and the destruction on penetration was greater. This was carried by the Ju 88P-4 and by some Hs 129B-2s as well as Me 410 A-1/U4 and B-2/U1. It was also fitted to or planned for the Ju 188S-1/U, Ju 288C, He 177A-3 and an Me 262A-1. A lightweight M-Geschoss loading was developed for air-to-air fighting. It was not popular because of reliability problems as well as its low rate of fire, so it saw far less use than the 3cm and 3.7cm weapons.

The BK 7.5 was likewise derived from the PaK 40 anti-tank gun and used its 75 x 714R ammunition, but with a reduced propellant loading in order to moderate the heavy recoil. This did not affect AP performance as the speed of the aircraft added about 80 m/s to the velocity at 300 km/h. The muzzle velocity of the 6.8kg shot was around 700 m/s. The gun was fitted to the Ju 88P-1, with a twelve-round magazine, and to the Hs 129B-3, but it appears that few aircraft were fitted with these large cannon and they saw very little action. As with the BK 5 (but even more so) these huge cannon had a crippling effect on aircraft performance and handling.

By the end of the war an astonishing range of large-calibre aircraft weapons was in the experimental stage, prompted by the calculation that a single direct hit by a shell of 5cm or 5.5cm calibre would be sufficient to destroy a heavy bomber. One was the 5.5cm Rheinmetall-Borsig MK 112, a compact, low-velocity API blowback gun which was in effect an enlarged MK 108, firing a 55 x 175RB cartridge. It was planned to fit two into the nose of an Me 262, with twenty-five rounds each, a similar armament with 50 rpg in the Arado Ar 234 jet and two underwing guns on the Do 335. The Americans continued the post-war development of this weapon for a while as the 'Gun, 57mm, T78\

At the other end of the large-calibre performance scale were the high-velocity 5cm and 5.5cm cannon which were intended to fit into the nose of heavy fighters such as the Me 410 and Me 262 jet in order to subject bomber formations to long-range artillery fire, a revival of the tactical thinking of the 1930s which had led to the MK 101. This was tried with a handful of Ju 88P-ls in the winter of 1942/3 and with BK 5-equipped Me 410s, which attacked a B-17 formation in May 1944. Neither experiment was a success, but despite this new weapons were developed.

The most promising of these large, high-velocity guns by the war's end was the 5cm Mauser MK 214 A, like the BK 5 based on the KwK 39 and using the same ammunition, but using a improved autoloader design to achieve 160 rpm while weighing 'only* 490kg. This was officially ready for use and there are some reports that it saw action, fitted to a Me 262 A-la(V), but without success. A more adventurous weapon was the 5.5cm Rheinmetall-Borsig MK 114. This fired the large, high-velocity 55 x 450B ammunition designed for the experimental FlaK 58 A A gun and was reportedly being developed for a stabilised mounting, to be aimed by a gunner, which was expected to improve the hit probability by at least five times. Performance was impressive, but the weapon was only at the development stage at the end of the war.

Heinkel 119
Installation of a 5cm BK 5 in the Me 41 OA-1IU4. Note the annular magazine around the breech

It is difficult to understand the Luftwaffe's obses- the lack of proximity fuzes greatly limited long-

sion with long-range air-to-air artillery fire. The range effectiveness and it is hard to see how even aiming problems were enormous and it was difficult the Me 262 could have been expected to survive to use smaller guns as 'sighters1 because of the dif- against the swarming USAAF escort fighters, given ferences in trajectory. For example, the Me 410 A- the need to fly a steady course for some time while

1/U4 was equipped with a pair of MG 151/20 as aiming and firing.

well as the BK 5, but with the trajectories adjusted

On the other hand, the short-range, low-velocity to coincide at 500m, the MG 151 projectiles varied MK 108 (and presumably even more so the MK

from 65cm higher than the BK s at 200m to 65cm lower at 700m. The timing problem was just as bad:

112) was well suited to the fast jet s ability to evade the escorts, get in amongst the bombers to fire at the MG 151 (M-Geschoss) projectiles took 0.952 close range, then speed away. It must be realised seconds to reach 500m, by which time they had slowed to 363 m/s. Even the conventional HE round that the effective velocity of the Me 262 s weapons was much greater than gun performance would for the BK 5 took only 0.625 seconds and was still indicate, as an 800 km/h attack speed (around 500

travelling at 736 m/s - the M-Geschoss would have been faster still. The Me 410 B-2/U-1 caused even more problems as this carried a pair of MG 131 as well; trajectories of the three types of gun did not coincide at any range. Even ignoring this problem.

km/h faster than the bombers) is equivalent to adding another 220 m/s to the muzzle velocity. In the case of the MK 108, this represents more than a 40% increase.

In their desperate efforts to obtain more

Anlage 3 b

800 m


Mu n dungs waagerechte B.K. 5 cm cm


9mm Trajectory

Mu n dungs waagerechte B.K. 5 cm

Mùndunqswaagerechfb M. G. 151

Trajectory curves for weapons installed in an Me-4I0B-2/Ul; 1 — 13mm M G 131, 2 = 15mm M G 151, 3 = 5cm BK 5

Mùndunqswaagerechfb M. G. 151

Trajectory curves for weapons installed in an Me-4I0B-2/Ul; 1 — 13mm M G 131, 2 = 15mm M G 151, 3 = 5cm BK 5

destructive power, German designers pursued some novel and occasionally far-fetched concepts. These included such weapons as the Gustloff HF 15, which loaded between seven and nine 15mm projectiles in one chamber, driven by one propellant charge at an effective rate of fire of 36,000 rpm. A simpler approach to achieving a high-rate burst of fire was taken by the Rheinmetall-Borsig SG 117, 118 and 119, all of which consisted of a vertically mounted cluster of several 30mm MK 108 barrels, each only capable of firing a single shot, arranged to fire in rapid sequence equivalent to 10,000-12,000 rpm as the fighter passed under the target. To cancel out the recoil, the block of barrels was designed to recoil downwards out of the aircraft.

The Germans also experimented with squeeze-bore automatic guns with the aim of increasing muzzle velocity, for example the MG 131/14/9, in which the chamber calibre was 14mm and the muzzle calibre 9mm, and even automatic recoilless weapons such as the 5.5cm Rheinmetall MK 115, which used combustible cartridge cases and was designed to achieve 300 rpm. Most of this ingenuity was wasted as none of these weapons saw service and all proved to be conceptual dead ends. Design efforts continued with more conventional weapons. Mauser designed the MG 215, initially in 13mm and later in 15mm, but neither saw service. Of much more long-term significance was the work to increase the rate of fire of aircraft cannon, leading to the literally revolutionary Mauser MG 213C, the forerunner of all revolver cannon to the present day.

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