10.5-cm Flak 38 and Flak 39 and 12.8-cm Flak 40

Field Marshal Erhard Milch, the head of the Luftwaffe’s Air Armaments Program and the second in command of the Air Ministry had suggested placing the larger-caliber guns in fixed positions already in March, and by June Hermann Göring issued an order to increase the numbers of anti-aircraft in static positions, including all 128-mm guns. Göring did allow some 128-mm flak guns to be sited on railroad cars to provide a mobile reserve for building up air defenses in threatened areas. The decision to emplace anti-aircraft guns in fixed positions was based on two considerations.

First, fixed guns required the diversion of fewer personnel and material resources. For example, by emplacing flak guns, the Luftwaffe eliminated the material expenditure associated with the production of mobile gun carriages. Furthermore, static sites greatly reduced the need for transport vehicles and trailers for moving the guns and their associated equipment and personnel, a nonmotorized heavy battery requiring fifty-three fewer persons than its motorized counterpart.

Second, the accuracy of the weapon could be improved to a limited degree in prepared positions, especially for flak guns of extremely large caliber. However, the main disadvantage associated with these weapons was the inability to move them to reinforce threatened areas when the sites they protected were not under attack. In the end, economic considerations outweighed tactical concerns as the Luftwaffe increasingly chose to build fixed anti-aircraft sites in place of mobile guns, a decision that would have important consequences as the fronts in the east and the west began to collapse in late 1944.

Luftwaffe studies indicated that at 29,500 feet, the 88-mm/Model 18 and 36 had only fourteen seconds to effectively engage a target, the 105-mm had forty-nine seconds, and finally the 88-mm/Model 41 and the 128-mm each had approximately sixty-eight seconds of effective engagement time. At 36,000 feet, only the 88-mm/Model 41 and the 128-mm were able to engage a target for a period of only thirty-one seconds. Immediately after this discussion, General of the Flak Artillery Walther von Axthelm noted, “At this time, the flak artillery does not dispose of any means of defense against the to be expected high-altitude aircraft.” Axthelm’s observation was correct, but his predictions concerning the projected developments in aviation technology proved widely exaggerated. In contrast to Rüdel, von Axthelm’s strategic foresight proved far less developed. For example, the Luftwaffe was well aware of American efforts to build the B-29, the technologically most advanced bomber of World War II, but even this aircraft, with a capability for cabin pressurization, had a service ceiling limited to 31,850 feet and a maximum speed of 358 mph. Axthelm may not exactly have been tilting at windmills, but he could be accused of either grossly overestimating his opponent’s capabilities or deliberately seeking to create an exaggerated threat in the hope of gaining more fiscal and material resources for his flak forces.


10.5-cm Flak 38 and Flak 39

Schwere Flak einer Küstenbatterie

A Flak 38 105 mm anti-aircraft gun at a coastal battery, 1942.

The 10.5-cm (4.13-in) Flak 38 and 39 resembled scaled-up versions of the 8.8-cm Flak 18 series, but used an all-electrical control system and a revised loading system. Intended for use by field units, many were later diverted to the Luftwaffe for the defence of the Reich and many were used on railway mountings.

As far back as 1933 the German military planners saw a need for an antiaircraft gun heavier than the 8.8-cm (3.465-in) Flak series, and both Rheinmetall and Krupp were invited to submit designs for a ‘shoot-off’ contest for 10.5-cm (4.13-m) weapons held in 1935, Rheinmetall won the contract with its Gerät 38, which duly went into production as the 10.5-cm Flak 38. This model had an electrical control system and a powered loading mechanism, but was soon replaced in production by the 10.5-cm Flak 39 with a revised electrical and fire-control data system.

Both 10.5-cm (4.13-m) Flak guns were intended for use by the German field armies, but in the event they were almost all employed in the home defence of the Reich. In appearance the Flak 38 and Flak 39 resembled scaled up Flak 18 guns, but there were many detail differences and proportionally the Flak 38 and Flak 39 were much heavier and bulkier weapons. In overall terms the Flak 38 and Flak 39 were complex weapons and were made more complex to manufacture by the use of a sectional barrel (for rapid change of the worn portion only after firing) on the Flak 39, Unfortunately, in action they proved to be little better than the 8.8-cm (3.465-in) Flak series as far as overall performance was concerned, and at one point it was even intended to replace them in production by the 8.8-cm (3.465-in) Flak 41 though this never happened: production of the Flak 41 was so slow that the 10.5-cm (4.13-in) Flak guns were kept on the production lines. When the war ended there were still 1,850 in service, most of these within the borders of the Reich.

Although intended as a field weapon, the Flak 38 and Flak 39 were really too heavy for the role. They used a scaled-up version of the mobile twin axle carriage of the 8.8-cm (3.465-in) Flak series, but even with the aid of integral winches and pulleys the guns were slow and awkward to emplace. Many were subsequently assigned to static emplacements, and 116 were mounted on special Flak railway trucks that rumbled around the Reich wherever they were needed. Each model needed a crew of a commander and nine men, though use of the manual loading system required a further two men.

The 10.5-cm (4.13-in) Flak series never acquired the fame of the 8.8-cm (3.465-in) Flak series, mainly because it was not widely used in the field and because its bulk and weight meant that it was only rarely used as an antiarmour weapon, Overall its performance was not as good as had been originally hoped, and despite a great deal of development work on a project known as the 10.5-cm Flak 40, which was to have had a longer barrel to fire a heavier projectile, the 10.5-cm (4.13- in) Flak guns were never ‘stretched’ to the same extent as the other German Flak guns. Instead production went steadily ahead at several centres until the war ended.


12.8 cm FlaK 40 Zwilling Twin mounted anti-aircraft, capable of firing 20 rounds per minute. Used mainly on flak towers. Production started in 1942 with 10 twin sets produced, another eight in 1943, and in February 1945 a total of 34 were available


Approximately 200 were mounted on railcars, providing limited mobility.

12.8-cm Flak 40



Only six mobile versions of the 12.8- cm Flak 40 were produced before production was switched to static versions only. This gun is carried on a Sonderhanger 220 in one load, but some guns were carried as two loads.

The idea of producing a German 128- mm (5.04-in) anti-aircraft gun was first mooted in 1936 when Rheinmetall was requested to produce a design known then as the Gerät 40. Progress on this design was not placed at a very high priority, so it was not until 1940 that the first prototype was ready. At that time it was intended that the Gerät 40 would be a weapon for the field army, but when the military saw the size and bulk of the prototype they decided that the weapon would be produced for static use only. The weapon was ordered into production as the 12.8-cm Flak 40.

By that time plans had already been made for a production-line mobile version, so the first six were produced on mobile carriages. The Flak 40 was so large that it proved impossible to carry the gun in one load over other than very short distances, so a two-load system was initially employed. Even this proved to be too cumbersome, and was later revised to a single load once again. Later versions were produced for static use only, and such was the overall performance of the Flak 40 that it was carefully emplaced around some of the main production and population centres such as Berlin and Vienna, Special Flak towers were built in some locations to make best use of these guns, and there was also a special railcar version to provide the guns with some sort of mobility.

Production of the static version began in 1942, but it was a costly and complex gun so by January 1945 there were only 570 in service, all of them based inside the borders of the Reich,

Soon after full-scale production began, the Flak 40 was joined by a twin version of the same gun known as the 12.8-cm Flakzwilling 40. This consisted of two 12.8-cm (5.04-in) Flak guns mounted side-by-side on the same mounting and provided with ‘mirror’ loading arrangements. These powerful gun combinations were used only on special Flak towers around the main centres of population within the Reich, and were so costly and difficult to produce that there were never many of them; even by February 1945 there were only 33 in service. The Flakzwilling (Zwilling, or twin) was introduced as it was realized that ever heavier anti-aircraft guns would be needed to counter the increasing performance of Allied bombers, and despite strenuous efforts to develop guns with calibres of 150 mm (5.9 in) and even 240mm (9.45 in), none got past the prototype stage at best and some failed to get even that far, Thus the twin arrangement of the Flakzwilling 40 was an attempt to produce at least some form of increased firepower to counter the Allied heavy bombers, and in the event it turned out to be an excellent anti-aircraft weapon.

As the war ended the original mobile Flak 40s were still in use, many more were in use on special Flak trains. A new 12.8-cm Flak 45 gun was under development as the war ended, and this would have been an even more powerful weapon than the original. Only a single prototype was completed.

Like its 88-mm counterpart, the 128-mm flak gun was experiencing production problems despite the fact that the initial prototype had been tested in 1937. By the end of 1942, only forty-five single-barreled versions of the gun and an additional ten twin-barreled versions had emerged from German factories. The twin-barreled versions were designed to sit atop the enormous concrete flak towers constructed in Berlin, Hamburg, and Vienna. In terms of performance, the 128-mm flak gun was undoubtedly the most capable antiaircraft weapon of World War II. In terms of efficiency, the 128-mm gun averaged 3,000 rounds per aircraft brought down, half as many as the 105-mm guns and less than one-fifth of the totals for the older 88-mm models. In a private conversation on the evening of August 28, 1942, Hitler evaluated the relative merits of the Luftwaffe’s anti-aircraft guns. He remarked:

The best [flak gun] is the 8.8 [cm]. The 10.5 has the disadvantage that it consumes too much ammunition, [and] the barrel does not hold up very long. The Reich Marshall [Göring] continually wants to build the 12.8 [into the flak program]. This double-barreled 12.8 has a fantastic appearance. If one examines the 8.8 from a technician’s perspective, it is to be sure the most beautiful weapon yet fashioned, with the exception of the 12.8 [cm].

The 128-mm flak gun was indeed an imposing and capable weapon. However, its length of almost twenty-six feet and weight of over 28,000 pounds made it essentially a fixed-base weapon despite the Luftwaffe’s efforts to build several large transporters to make the gun mobile. By 1942, resource restrictions led to the cancellation of orders for the massive Meiller transporters, and the 128-mm guns were assigned to specially designed railroad flatbed cars, the roofs of the flak towers, or in fixed positions throughout the Reich.

10.5-cm Flak 38 and Flak 39 Reference Pictures


4 thoughts on “10.5-cm Flak 38 and Flak 39 and 12.8-cm Flak 40

  1. The information on the 128 mm AAA was helpful. I’m writing about a B-24 pilot B-24 who flew the mission to bomb the synthetic refinery at Pölitz on June 20, 1944. It was protected by 85 of these guns.



  2. I am modeling for gaming a 10.5cm Flak 40 in 1/100 scale by using a 1/72 scale Flak 36 gun. From this article that gun would either be mounted on a train or a fixed mount. I am moving to check the pictures available online. It looks right now like I need to remove the gun shield. Can this be confirmed? No gun shield.


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