One of the main reasons for the success of the
Blitzkrieg against the French and British Armies, in May 1940, was the aerial superiority obtained when the Messerschmitt Bf 109 E-3 entered service with the Luftwaffe. It happened at the right time, when the main French fighter Morane-Saulnier M.S.406 was replaced by the second generation fighters Dewoitine D.520 and Arsenal VG 33. During the
Phoney War,
l’Armée de l’Air tried to fill the gap with the Bloch M.B.152 and Curtiss H.75A fighters, helped by the British Hawker Hurricane Mk.I. But the Messerschmitt would prove superior.
This seems to be the origin of the commonly accepted paradigm about the assumed inferiority of the French technology. It is not common knowledge that France already had operational naval radar in 1934. And that, at the beginning of June 1940, the antiaircraft artillery defending Paris was controlled by the most advanced radar in the world, able to operate in wavelengths from 80 to 16 cm against the 3.5 to 1.5 m of the British or the 2.4 m to 53 cm of the German radar.
The French scientists were also ahead of their German equivalents in the field of nuclear fission. By early 1940, the CNRS controlled the highest reserve in the world of uranium (8 tons coming from the Belgian Congo) and 200 kg of heavy water from the Norwegian enterprise
Norsk Hydro.
The French tanks of 1940 had better armour and armament than the Germans. The
Marine Française (the French combat fleet) was superior to the
Kriegsmarine in firepower with the
Béarn carrier and six squadrons of Loire Nieuport L.N.401/411 dive bombers that technically surpassed the German Ju 87.
The destructiveness of the air-to-air weapons installed in the French fighters was slightly higher that their German equivalents, although the quality of the aiming devices OPL 31, RX 39 and GH 38 used by
l’Armée de l’Air was somehow inferior to the Zeiss
Revi C/12 reflector gunsight of the Luftwaffe. The following text compares the armament used by the French and German fighters during the Battle of France
MAC 34 (7.5 mm)
Designed and built by
Manufacture d’Armes in Chatellerault (MAC) during the year 1934, it was the standard machine gun used by the French fighters during the
Phoney war and the Battle of France. The commonest model was the MAC 34A (for
Aile, the French word for wing), gas operated, electro pneumatically loaded, fed from a helical pan 'drum' magazine containing 300 rounds.
The MAC 34 was installed under the wings of the Morane-Saulnier M.S.406 and Potez 631 fighters in aerodynamic fairings with the drum magazine housed within the wing. The joining system was of the cardan type and could be regulated for convergence at an affective range of 250 m. The mechanism was very sensitive to cold temperatures and might occasionally cause a great firing dispersion.
The belt-feed MAC 34 M39 with 500-675 rounds was developed to solve this problem and reduce drag. It could be installed within the wing of the M.S. 410, Dewoitine D.520, Arsenal V.G. 33 and Bloch M.B.155 which all constituted the 2nd generation of French fighters of the war. There was a variant developed for the M.S.406 exportation version that could be integrated with the engine (firing through the propeller hub) and replaced the H.S.9 cannon. It was a version of the MAC 34A which was fed with a 500 rounds drum.
Another variant with flexible mounting, named MAC 34T (for
tourelle, or turret in French) was used in bombers and
multiplace fighters. The MAC 34 had a high rate of fire because of the short length of its barrel. Consequently, the muzzle velocity and destruction capacity were reduced up to a point of being considered an inefficient weapon against the He 111, Do 17 and Ju 88 bombers. The MAC 34 fired the short cartridge mod. 1929 with Armour Piercing (AP), Armour Piercing/Incendiary (API) and Armour Piercing Tracer (APT) ammunition. In the M.S. 406 and M.B. 152 the three types of ammunition were sequentially stored in the drums and belts, 40% of AP, 40% of API and 20% of APT.
In the Dewoitine D.520, two machine guns were loaded with AP and the other two with API (a hollowed AP that was then filled with phosphor). The incendiary power of the API was big and its penetration capacity almost non-existent. Additionally, its ballistic features differed from the AP type in the different weight between both bullets. The API was thermally unstable. The heating system of the D.520 weapons had to get disconnected after several cases of spontaneous ignition of the phosphor at temperatures between 40° and 45° C.
Rheinmetall Borsig MG 17 (7.92 mm.)
Designed to be installed over the engine of the German fighters, it should fire through the propeller disk by means of a synchronization device. Therefore, its rate of fire was lower than that of the MAC 34, a shortage that was partially compensated by the greater capacity of destruction of the projectile, and its higher effective range, due to the use of a long barrel.
It was a recoil operated type weapon designed and built in 1934 by the Rheinmetall Borsig firm. It used an electro pneumatic loading system, with belt feeding, and fired ammunition of the armour piercing (50%), armour piercing/incendiary (40%) and high explosive/incendiary (10%).
The latter, when exploding by impact, informed the pilot that his target had been hit and was used to replace the conventional tracers. The Lutwaffe technical staff thought that the tracers were not convenient during dog fighting as they might alert the enemy pilot of the firing aimed to him.
The Messerschmitt Bf 109 E-1 carried two MG 17 over the engine with 1000 rounds per gun (r.p.g.) and another two in the wings with 420 r.p.g. having a total weight of fire of 0.72 kg/sec. This disadvantageously compared to the 2 kg/sec of the Morane-Saulnier M.S.406 and the 1.46 kg/sec of the Hawker Hurricane Mk.I.
To balance this situation the Bf 109 E-3 (with a firepower of 2.66 kg/sec) entered service at the beginning of the autumn of 1939, replacing the MG 17 of the wings with two MG FF cannons.
The Messerschmitt Bf 110 heavy fighters of the C series also took part in the Battle of France. They were equipped with four MG 17 machine guns with 1000 r.p.g. and two 20 mm MG FF cannons with 180 r.p.g. located in the nose.
Ikaria MG FF (20 mm.)
During the 20s, the Swiss firm SEMAG committed itself to the design of the 20 mm gun Becker used during the WWI by some German bombers. During the first years of the 30s, the research was continued by the Swiss firm Oerlikon who, in 1933, started to commercialize three basic models using cartridges of progressive length and power. They were the Oerlikon FFF type (72 mm case length), the Oerlikon FFL type (100 mm case length) and the Oerlikon FFS type (110 mm case length).
The FFS was acquired by
l’Armèe de l’Air to serve as a base for its own Hispano Suiza H.S.7 and H.S.9 designs which were both modified for aircraft engine mounting. The FFL was acquired by the Imperial Japanese Navy in 1939 and manufactured under license from 1941 onwards, as 99-2 Type, to be used in the
Zero-Sen fighters. The FFF was chosen by the German, Polish and Romanian Air Forces to equip the Bf 109 E-2/E-3, Bf 110C, PZL P-24 C/F/G and IAR 80 fighters.
The Luftwaffe version was extensively modified to adapt the original design to the German production techniques, being mass manufactured by the
Ikaria Werke Berlin as MG FF (
Maschinen Gewehr Flügel Fest = Machine Gun Wing Installation) from 1935 onwards. It was the lightest short barrelled weapon in its class with just 28 kg. But it had a lower effective range and power of penetration than the contemporary French and Swiss designs.
These shortages were partially compensated by a higher rate of fire and the introduction of the MG FFM (
Modifizierung = Modification) which could fire the HE ammunitions
Minengeschoss.
It is unclear if the MG FFM was ever used during the Battle of France. Some authors state that the Bf 109 E-2 were armed with four MG 17 machine guns and at 20 mm cannon located behind the engine, firing through the axis of the hub propeller. As per this version of facts, the 'M' meant
Motor.
The Bf 109 E-2 passed through some operational tests with discouraging results because of the strong vibrations that the cannon produced in the engine crankcase during firing. Apparently, the decision to mount the two cannons in the wings of the Bf 109 E-3 went against the initial German project that preferred the French
moteur-canon device. This system was eventually adopted as a matter of urgency after the failure of the Bf 109 E-2 to alleviate the big difference in firepower between the Bf 109 E-1 and the Morane and Hurricane fighters.
The MG FF fired 20 mm ammunition of the 20 x 80RB type that could be HE (134 g), HEI (115 g) or
M-Geschoss (92 g). When installed in the Bf 109 E and Bf 110 C fighters of, it used a 60 rounds drum while the Do 17Z night fighters used a 15-45 rounds drum which could be manually replaced in combat. The Luftwaffe always considered the MG FF a transition weapon to fill the gap until the excellent MG 151 was available.
Oerlikon FFS (20 mm)
A small amount of these guns, together with their manufacturing license, was acquired by France in 1933. The FFS was not suitable for aircraft engine mounting because of the too advanced position of the recovery cylinder/yoke unit and had to be modified as Hispano-Suiza H.S.7. The French developed the SPAD S.XII in 1916 for the destruction of balloons. It was armed with a single-shot SAMC (APX) 37 mm cannon mounted between the V8 cylinder blocks of the 200 hp Hispano-Suiza 8c engine.
The
moteur-canon was not very successful, due to its slow reloading capacity and excessive recoil shock, and the SPAD S.XII was abandoned, but the French retained the idea until the arrival of the right time. This came in 1932 with the 690 hp liquid-cooled engine Hispano-Suiza H.S.12 Xbrs of 12 cylinders in 60º 'Vee' configuration.
This was the right engine to combine with one 20 mm Oerlikon FFS cannon -manufactured under license as Hispano-Suiza H.S.7- mounted between the two-cylinder banks. The crankcase was strengthened, and the reduction gear modified to bring the hollow propeller shaft in line with the gun barrel.
The ammunition was the same than that of the Swiss gun, contained in a 60 rounds drum. The H.S.7 was heavier, due to the fixation system to the engine, and had a rate of fire of just 350 rpm (compared to the 470 rpm of the Oerlikon) to protect the engine from any destructive vibration. This engine was then known as Hispano-Suiza 12 Xcrs (‘c’ for
canon = cannon) and had reduced its power to 680 hp, consequence of the modifications made in the gearbox. The new
moteur-canon was installed in the Dewoitine D.510 fighter and in the Loire-Nieuport L.N. 401/411 dive bombers of
l’Aeronavale which fought the panzers on 15 May 1940.
The Germans tried to use the
moteur-canon system with their Bf 109 V4, C-2 and E-2 fighters, trying different combinations of Jumo 210 and Daimler Benz 601 engines with MG 17 machine guns and MG FF cannons. But they found insoluble problems of cooling and crankcase destructive vibrations. On October 1940, they finally adapted an MG FF cannon behind the DB 601N engine of the Bf 109 F-0, but the device suffered structural damages during tests. The problem could not be solved until the MG 151/20 gun was available and could be installed in the Bf 109 F-2 in March 1941.
Hispano-Suiza H.S. 9 (20 mm)
In 1935 a 900 hp improved version of the H.S.12 Xcrs engine appeared, known as Hispano-Suiza H.S.12 Ycrs. The integrated cannon was also an improved version of the H.S.7 although somehow lighter and with 420 rounds per minute (r.p.m.) rate of fire but maintaining the same muzzle velocity and destructive power than the Oerlikon. It fired the same type of HE, HET and AP ammunition than the Oerlikon, stored in a 60 rounds drum.
The HE type model 1936 was identified by a yellow band, the HET of 1939 with a yellow and blue band and the AP was overall painted in black. The HE had a 1937 model 17/19 B impact fuse and the HET also had a self-destruction system. The
moteur-canon was very successful in the market, being acquired by the Czech Air Force to equip their Avia B-534, B-536 and B-135 fighters and by the Yugoslavian Air Force for their Ikarus Ik-2 and Rogozarski Ik-3. It was also used by
l’Armèe de l’Air to power the Morane-Saulnier M.S.405.
Hispano Suiza H.S. 404 (20 mm)
After the experience in combat against the fast and well armoured He 111 and Do 17 German bombers obtained during the Spanish Civil War, the engine designer Mark Birkigt decided to develop the H.S. 404 with higher performance. It was gas operated with a 166 per cent higher rate of fire and a muzzle velocity of 880 m/sec compared to the 820 m/sec of the H.S.9. The new weapon entered service in 1939 and could be installed either in the H.S.12 Y-31 engines of the M.S. 406 or in the H.S.12 Y-45 of the Dewoitine D.520, M.B. 155 and Arsenal VG 33 fighters.
The H.S. 404 fired 20x110 ammunition (that was not interchangeable with the 20x110 RB cartridges of the H.S .9) stored in a 60 rounds drum. There were six different types: HE model 1938 or 1939 (130 g) with a 17/19B 1938 model fuse identified by a yellow band, HET identified by a yellow and a blue-grey band, AP (165 g) black projectile with a red band, APT with black nose and metal-grey-metal-red bands, AP/HE with red-yellow-green bands and HEI with red-yellow-blue bands.
This type of ammunition had not been sufficiently tested and caused several accidents during combat. The Dewoitines D.520 of the G.C.I/3 were specially affected, experiencing premature explosions within the barrel when firing the second burst. Between 5 and 8 June 1940 the M.S.406 of the G.C.I/6, G.C.II/2 and G.C.III/7 were used in ground attack task against the German tanks with AP and APT ammunition.
The manufacturing of the H.S. 404 was slow and costly. At the beginning of the war only 928 units had been delivered to
l’Armée de l’Air and in March 1940 there were 2,319 units available.
The H.S. 404 was a formidable weapon when integrated in a Hispano-Suiza engine or installed in the nose of the twin engine Potez 631 fighters. However, it was less resilient when installed in the wings of the Bloch fighters, causing different problems of vibration, stoppage, freezing and dispersion of firing.
The H.S. 404 was acquired by the RAF and manufactured under license in the United Kingdom as Hispano-Suiza Mk I, Mk II and Mk V and as Hispano AN/M2 in the USA. A version over flexible mounting was also manufactured to be used by the rear gunners of the French medium bombers LeO 451 and Amiot 354.