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WW2 German SPAAGs

3.7 cm Flak 43 in Keksdose-Turm auf Pz.Kpfw.III Fahrgestell

Germany (1944)
Self-Propelled Anti-Aircraft Gun (SPAAG) – 1-2 prototypes and 11-18 built

The German ground forces were hard pressed by the Allied ground attack aircraft during the second half of World War II. The Panzer and Sturmartillerie units were hit especially hard by these attacks. Towards the end of the war, the Panzer branch of the Army came up with a temporary solution in the form of the Flakpanzer series based on the Panzer IV. The Sturmartillerie (Eng. assault artillery) units, equipped with the StuG III based on the Panzer III, also asked for Flakpanzers (Eng. anti-aircraft tanks) for their own protection. As they were unable to acquire these vehicles, a possible solution was to simply develop and build a Flakpanzer based on the Panzer III chassis. While small numbers were built, they were simply too late to have any real effect on the war’s outcome. Sadly, besides a few drawings, there are no known surviving photographs of this vehicle.

Besides a few drawings, to this day, there are no surviving photographs of the Flakpanzer III. Source: Panzer Tracts. 12-1

Context and Development

By 1943, it had become apparent that the Luftwaffe was losing control of the skies, which left the German ground forces severely exposed. The armored formations were often the main focus of the Allied ground attack aircraft operations. While the Germans employed a number of anti-aircraft vehicles based on half-tracked (Sd.Kfz.10/4, Sd.Kfz.6/2, Sd.Kfz.7/1, etcetera) and truck chassis. These had very limited or no armor, and thus they were vulnerable to enemy fire either from the ground or the air. To provide adequate armed and armored anti-aircraft vehicles, the Panzer units were supplemented with several Flakpanzers built using different tank chassis, raging from the old Panzer I (built in a small series and more of an improvisation than a properly design vehicle), Panzer 38(t), to the Panzer IV. The Panzer IV-based anti-aircraft vehicles (Mobelwagen, Wirbelwind and Ostwind) proved to be most effective but were introduced for service late into the war.

The quadruple 2 cm gun-armed Wirbelwind was probably the best German Flakpanzer IV produced during the war that saw combat in some numbers. While the later Ostwind had a stronger 3.7 cm gun, it was built too late and in too small numbers and only saw limited combat action. Source: WIki

The In 4 (artillery branch – Inspectorate 4) wanted a similar vehicle for their own assault artillery units. To facilitate the production of spare parts and maintenance, the new vehicle should have been based on the Panzer III chassis, the same as the StuG III was using. For this reason, in October 1944, a military delegation was dispatched to Deutsche-Eisenwerke in Duisburg to inspect the available anti-aircraft turret designs. For the planned Flakpanzer III production, in November 1944, In 4 managed to obtain a monthly delivery of 30 StuG III chassis. In addition, some 90 Panzer III superstructures were also allocated for this project.

In December 1944, Regierungsbaurat Becker was dispatched to the Ostabau Sagan factory, where the Ostwind and Wirbelwind turrets were being built. Becker proposed to modify the Ostwind and Wirbelwind turrets so that these would be able to fit to the smaller diameter of the Panzer III turret ring. The Obstbau officials simply rejected this proposal, not willing to engage in this project. It is possible that the Obstbau officials were influenced by the Panzer branch, which had, to say the least, a ‘tense’ relationship with the assault artillery branch. These tensions had been raging since even before the war had actually started. Another simpler explanation was that Obstbau Sagan simply lacked production capabilities and was barely managing to keep up with Flakpanzer IV turret production. As the Obstbau experience and production facilities (limited as they were) would have greatly sped up the assault artillery Flakpanzer project, In 4 was left empty-handed.

Nevertheless, not willing to admit defeat, In 4 initiated development of the assault artillery unit’s own Flakpanzer project. For the main base for the construction of such a vehicle, the Sturmgeschützschule (Eng. assault gun school) at Burgen was chosen. In early 1945, Deutsche-Röhrenwerke delivered an Ostwind turret with an enclosed floor. Depending on the source, a Wirbelwind turret was also allocated for this project. Additionally, two 3.7 cm Flak 43 and two 2 cm Flakvierling 38 anti-aircraft guns, along with two (or one) Panzer III chassis were also acquired.

While it was not adopted, a Wirbelwind armed Flakpanzer III was also tested. Source: Walter J. Spielberger.Gepard the History of German Anti-Aircraft tanks

The two prototypes were successfully completed and tested by March 1945. While testing the Ostwind turret, the Burgen engineers noted that besides the standard 3.7 cm Flak 43, the installation of 2 cm Flakvierling 38 could be done without any major problems. In early March 1945, the Heeres Waffenamt gave permission to allocate some 18 Ostwind turrets from Ostabau Sagan stocks to the Flakpanzer III project. An additional 72 turrets were yet to be built.

Name

Due to its late and unofficial introduction into service, it is unknown if this vehicle ever received any official name. In the well-known Panzer Tracts series, issue 12-1, Flakpanzerkampfwagen IV and other Flakpanzer projects, this vehicle is named the 3.7 cm Flak 43 in Keksdose-Turm auf Pz.Kpfw.III Fahrgestell. However, a quite common short name is the Flakpanzer III. This article has and will use this designation for sake of simplicity.

Production

While In 4 requested 90 Ostwind turrets, only around 18 (the precise number is unknown) were actually delivered. The Flakpanzer III project would reach a quick end as it was, in essence, canceled by the Albert Speer Emergency Armament Production Program. This decision also encompassed the previously mentioned 18 turrets. Nevertheless, the Commanding General of Artillery, who was part of the German Army General Staff, urged for the completion of at least these 18 vehicles. He also requested special permission to build the remaining 72 turrets at a production rate of 12 per month. Due to the deteriorating war situation, his request was rejected. Despite this rejection, the Sturmgeschützschule at Burg managed to build a small number of Flakpanzer IIIs. If these were all armed with the 3.7 cm or some with the 2 cm anti-aircraft guns is unknown.

Specifications

Sadly, there is little to no information about the precise technical characteristics of the Flakpanzer III. A number of educated guesses can be made based on the similarities to the Panzer IV-based Ostwind project.

The Flakpanzer III chassis

As already mentioned, the Flakpanzer III was to be built using a combination of StuG III chassis and Panzer III superstructures. Which precise version of both was to be used is not known. Use of repaired (returned from the front) or even training vehicles could have been possible by the desperate Germans in 1944 and 1945. While the modification of less combat-worthy Panzer IIIs and StuG IIIs may, at first, seem like a good idea, the production of this tank was discontinued in 1943, thus limiting the potential large-scale production of such vehicles. However, the StuG III was still in production.

Suspension and the Engine

The suspension and running gear were the same as those of the original Panzer III, with no obvious changes to it. It consisted of torsion bar suspension with six small road wheels. Additionally, there were two front drive sprockets, two rear idlers, and six return rollers in total. The engine was the Maybach HL 120 TRM that produced 265 hp at 2600 rpm. With the removal of the original turret and replacing it with the new one, the weight was probably around 20 to 21 tonnes. This is at best just as a guess, as there is no information about it. This meant that the overall speed would not be changed much, which was around 40 km/h. The operational range would also remain the same, at 155 km.

The Panzer III suspension is visible here. Source: https://www.worldwarphotos.info/gallery/germany/tanks-2-3/panzer3n/

The Hull and the Superstructure

The Panzer III superstructure was probably unchanged. The driver’s front observation hatch and the ball-mounted hull machine gun were possibly kept as well. The most obvious place that would see a necessary modification were the Panzer III’s interior and the turret ring housing. In order to make a stable firing platform for the new turret, two (or more) metal beams were welded inside the Panzer III hull, probably a more or less direct copy from the Odtwind construction. How the engineers at the Burgen assault gun school placed the Ostwind turret, with its larger (1,680 mm) diameter on a smaller 1,520 mm diameter Panzer III turret ring is unknown.

The Turret

While both the Ostwind and Wirbelwind turrets were tested on the prototypes, the In 4 officials decided to use the Ostwind turret for the Flakpanzer III. The Ostwind turret was also known by the humorous Keksdose (Eng. cookie tin) nickname. It had a simple design, constructed by using 12 larger armored plates (placed at 30°) welded together. The turret was open-top, which provided a good all-round view, but offered no top protection. While initially there were plans to partly cover the top, due to a lack of resources and to avoid delays, this was never implemented. The overall armor thickness of the turret plates was only 16 mm, which provided protection from small arms fire and shrapnel. The Ostwind turret also had an additional pyramid-shaped sheet of armor welded to the lower front armor. Its purpose was to provide additional protection against any possible ricochet (from smaller caliber rounds) in the direction of the vehicle hull.

The Flakpanzer III’s traverse turret mechanism was probably taken directly from the Ostwind. This was in general a simple mechanism, by using a steering rod to connect the Flak 43 traversing mechanism to the Panzer III turret ring. This allowed the crew to move the turret by using the main gun traverse. The armored shield wall construction was placed on a ring-shaped turret base welded to the hull top, with added ball bearings to help with the rotation. If any additional modifications were made is unknown due to the lack of information.

The Ostwind had a simple design that provided the crew with small-caliber fire and shrapnel protection (from the side and not from the top). Source:D. Terlisten, Nuts and Bolts Vol.13 Flakpanzer, Wirbelwind and Ostwind.

For extra protection, the Ostwind turret received a pyramid-shaped sheet of armor welded to the lower front armor. The Flakpazer III would probably also have this feature. Source: D. Terlisten, Nuts and Bolts Vol.13 Flakpanzer, Wirbelwind and Ostwind.

Armament

The main weapon used was the 3.7 cm Flak 43 built by Rheinmetall-Borsig. It had a new gas-operated breech mechanism which was loaded with a fixed loading tray with eight-round clips. In order to be installed in the new Ostwind turret, some modifications were needed. The lower part of the carriage and the original gun shield were removed. In addition, the spent ammunition basket was smaller due to the turret size. Only the small rectangular shield in front of the gun was left in order to cover the front embrasure opening. The Flak 43 could rotate a full 360°, with a range of gun elevation between – 10° to + 90°. The maximum rate of fire was 250-300 rounds per minute, but 150-180 was the more practical rpm. It is not clear, but it is estimated that between 400 to 1,000 rounds of spare ammunition were carried inside the vehicle. With a muzzle velocity of 820 mps, the maximum effective ceiling was 4,800 m. The upper right front armor plate had a small hatch that could be opened to allow the gunner to see and engage ground targets.

For self-defense, the crew could rely on the hull-mounted MG 34, retained from the Panzer III design, and their personal weapons, which included the MP-38/40 submachine gun, pistols, and hand grenades.

The 3.7 cm Flak 43 Source: Pinterest

Crew

The Flakpanzer III crew would most likely have consisted of a commander, one or two gunners, a loader, a radio operator, and a driver. The driver and radio operator were placed in the vehicle hull, while the remaining crew were positioned in the new cramped turret.

Close up view of the Panzer IV Ostwind turret crew positions. The gunner is to the right and the loader and commander to the left. As the Flakpanzer III used the same turret, the crew configuration would not be changed much. Source Pinterest

In combat

The few constructed Flakpanzer III were actually rushed into combat. The following Sturmgeschütz Brigaden (Stu.G.Brig.) were known to have operated some Flakpanzer IIIs. In mid-March 1945, Stu.G.Brig.224 had 2 vehicles (one operational), while Stu.G.Brig.341 had 3 vehicles (two operational). The last unit to be equipped with Flakpanzer IIIs was Stu.G.Brig.667, which had two operational vehicles (out of four). All Flakpanzer IIIs saw service in the West by the end of the war. Whether they were actually used in combat or their performance is sadly unknown.

Conclusion

To draw a proper conclusion about the Flakpanzer III is almost impossible due to a lack of information. The use of a cheaper Panzer III chassis for a Flakpanzer idea had some merits. The much-needed Panzer IV chassis could instead be used for tanks or even in anti-tank configurations. In the end, while a potentially good idea, by the time it was implemented, it was simply too late to have a real impact on the war’s development.

Representation of the Flakpanzer III based on the available descriptions, as no photos have survived. Illustration by David Bocquelet, modified by Pavel ‘Carpaticus’ Alexe.

3.7 cm Flak 43 in Keksdose-Turm auf Pz.Kpfw.III Fahrgestell

Dimensions L-W-H 4.6 m x 2.12 m x 2.4 m
(ft in x ft in x ft in)
Total weight 9.4 tonnes
Crew Commander, Gunner, Loader, Driver and Radio operator
Armament 3.7 cm Flak 43
Secondary Armament 7.92 mm M.G.34 machine-gun
Turret Armor All around 16mm
Hull Armor 10-80 mm
Propulsion Maybach HL 108 TR 265 hp at @ 2600 rpm
Top road speed 40 km/h (25 mph)
Max. road range 155 km ( miles)
Total production 1-2 prototypes and 11-18

Source

One reply on “3.7 cm Flak 43 in Keksdose-Turm auf Pz.Kpfw.III Fahrgestell”

Interesting Article, another “too little, too late” attempt of the German’s to find a simple SPAAG to produce and use. Thanks For Sharing!

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