Category: WW2 German SPAAG Prototypes

German Reich (1943)
Self-Propelled Anti-Aircraft Gun – 1 Prototype Built

In the later stages of the Second World War, the Germans lost control over the skies and their ground forces had to endure extensive enemy air attack raids. The use of self-propelled anti-aircraft guns (SPAAG) based on half-track chassis offered some way to fight back, but these were themselves highly vulnerable, as they lacked proper armor protection. A SPAAG based on a tank chassis was more desirable. Early attempts were made in the form of the Flakpanzer 38(t), but this was more of a stopgap solution than a proper design. In 1943, more serious work was conducted using the larger Panzer IV chassis. This would lead to the creation of the first Flakpanzer IV, which would be a stepping stone to later German SPAAG development. Eventually, this would lead to the 2 cm Flakvierling auf Fahrgestell Panzer IV, or Flakpanzer IV.

Search for an Anti-Aircraft Tank

The development of a SPAAG based on a tank chassis was an idea that came to circulate in German military circles back in 1942. For this reason, Krupp was instructed in September 1942 to develop a lightweight chassis that would be able to be armed with a variety of weapons, ranging from 2 cm to even 5 cm anti-aircraft guns. The overall weight, with the armament, seven-man crew, and ammunition was not to exceed 4.5 tonnes. The armament and its crew were to be protected by folding armored walls. To speed up development time, the use of the Panzer II  ‘Luchs’ chassis was proposed for the project. Given the cancellation of the Panzer II Luchs, Krupp instead proposed the ‘Leopard’ chassis in early November 1942. As the Leopard suffered the same fate as the Luchs, this idea was also scrapped. Interestingly, Rheinmetall also proposed its version of an anti-aircraft tank based on the VK13.03 chassis. In comparison to the Krupp design, the Rheinmetall project offered a somewhat better design, as it had a fully rotating and mostly fully protected, albeit open-top, turret. While a wooden mock-up was built, nothing came from this project.

In January 1943, the use of a highly modified Panzer IV chassis was proposed instead. While the basic overall design would remain the same, the chassis was to be shortened and used only six doubled road wheels on leaf suspension on each side. This was to be armed with either the 2 cm Flakvierling, the 3.7 cm Flak, or even the more powerful but extremely flawed 5 cm and 5.5 Flak guns. The fighting compartment was to be protected by a box-shaped superstructure with folding walls, each consisting of two 10 mm spaced armor plates. Initially, the whole project was deemed crucial, so Krupp was instructed to build two prototypes to be used for evaluation and testing.

Due to the overburden German production and industrial capabilities, the introduction of another tank chassis was deemed unnecessary. A simpler temporary solution was needed. Krupp was informed that the anti-aircraft tank based on the modified Panzer IV chassis was canceled. This did not stop Krupp from actually continuing working on this project, and, in March 1944, all necessary components for its construction were ready. While some components were assembled, it is unlikely that the vehicle was completed by the war’s end.

The Flakpanzer IV

During May 1943, various German Army, including armament and tank, commissions met to discuss a proper solution to the general lack of anti-aircraft protection for the Panzer Divisions. The use of a cupola-mounted 7.92 mm machine gun was deemed almost useless in this role. Installation of stronger anti-aircraft weapons on the Panzer turrets was also not possible. The half-track anti-aircraft vehicles were also deemed not up to the task, mostly due to their weak protection. The only feasible solution was to develop an anti-aircraft vehicle based on a tank chassis.

The Luftwaffe (German Air Force) design office (GL/Flak 4) gave new instructions to  Krupp to cease all work on previously ordered projects and focus on developing an anti-aircraft tank based on the regular Panzer IV chassis. At this point of the war, the Luftwaffe was still responsible for providing anti-aircraft protection to the German ground forces, so to some extent, it was their responsibility to develop such a vehicle.

The contract for this project was officially awarded on 8th June 1943. To speed up the development and production process, the whole design was to be as simple as possible. As a temporary solution, the armament would consist of the 2 cm Flakvierling. This anti-aircraft gun and its crew were to be protected by four hinged armored walls. The decision to use this arrangement and not an enclosed turret was mostly based on the thinking that the anti-aircraft gun crew had to be able to have a good all-around view in order to be able to detect a fast-moving enemy aircraft. This thinking would prove to be flawed and later anti-aircraft Panzers would have almost fully protected turrets.

Krupp informed the Luftwaffe officials that the completion of the first prototype was expected to be ready by September 1943 if a Panzer IV chassis was provided in time. Krupp kept its promise and the prototype was completed by the end of September 1943 and presented to the German Army officials for inspection and evaluation. This vehicle was designated as 2 cm Flakvierling auf Fahrgestell Panzer IV, but this article will refer to it as Flakpanzer IV for simplicity.

Design

Compared to its later 3.7 cm armed successor, there is quite a small amount of information on the overall construction characteristics of the first Flakpanzer IV. Which precise chassis was used for its construction is not clear in the sources, but it is likely to have been an Ausf.G version.

Suspension and Running Gear

The Flakpanzer IV suspension and running gear were the same as those of the original Panzer IV, with no changes to the overall construction. They consisted of eight small doubled road wheels on each side suspended in pairs by leaf-spring units. There were two front drive sprockets, two rear idlers, and eight return rollers in total.

Hull and the Engine Compartment 

The original Panzer IV hull design did not receive any major change. The later Flakpanzer IVs utilized the standard Maybach HL 120 TRM engine but slightly modified to give out 272 [email protected],800 rpm instead of the usual 265 [email protected],600 rpm. If this was implemented on the Flakpanzer IVprototype is not clear.

Superstructure

A major change in comparison to a normal Panzer IV was the introduction of a larger and simpler rectangular-shaped superstructure. It was slightly enlarged and had four vertical sides. The machine gun ball mount was removed and replaced with a machine gun firing port. This port was protected by a round cone-shaped cap. It was like a plug, connected to a chain, and when in use, the armored cover would simply be pushed out by one of the crew members. The Panzer IV driver’s observation hatch remained unchanged. On top of the superstructure, four hatches were placed, two to the front and two more to the rear. The two front hatches served as entry points for the driver and the radio operator. The rear positioned doors served to access extra storage for spare ammunition.

Fighting Compartment 

On top of the superstructure were the main gun, crew, and protective folding walls. In the center of this compartment was a round-shaped mount on which the main gun was positioned and which could rotate 360°. It was protected by four large folding armored walls. Whilst driving, these walls were fully raised and the main 2 cm Flak gun was fixed in position, with its four barrels raised up. The front and rear plates also had two small hinged parts. These could be swung outwards and allow for the side plates to be fixed at an outward angle. This was done to allow more space for the crew during an aerial engagement while still providing protection from ground fire. For the installation on the Flakpanzer, 2 cm Flak gun’s shield had to be slightly modified. On the outside of the left and right side walls, two small metal rods were placed. These provided stability to the walls when fully folded down. Engagement of ground targets was possible only when all four walls were placed horizontally. This also provided the crew with additional working space, but left them almost completely exposed to enemy fire.

The main reason for using a folding wall was to provide the crew with an excellent overall view of the surroundings, especially of the sky, where fast-moving enemy aircraft had to be spotted quickly. This would, in theory, give the crew time to prepare for firing. In reality, lowering the side walls would take valuable time and leave the crew exposed to enemy fire.

Armament

This vehicle was armed with the 2 cm Flakvierling 38 anti-aircraft gun. A well-known anti-aircraft gun of the Second World War, it was designed by Mauser-Werke to replace the older 2 cm Flak 20 and was introduced in May 1940. Its effective firing range was between 2 to 2.2 km, while the maximum horizontal range was 5,782 m. The maximum rate of fire was 1,680 to 1,920 rpm, but 700-800 rpm was a more appropriate operational rate of fire. The elevation was –10° to +100°.

Whilst driving, the gun was fixed in position and could not be moved. In theory, the engagement of ground targets could be done in an emergency by lowering the front wall. However, the gun would have no possibility to traverse and the driver had to move the whole vehicle to hit moving targets. When engaging air targets the side walls could be partially lowered to a 30° angle. Ground targets could be engaged effectively only when all four armored walls were fully lowered.

While the 2 cm Flakvierling 38 was fed by 20 round magazines, not many sources mention how much ammunition was carried inside the vehicle. The gun itself had a special ammunition box in its base on both sides, where up to 8 magazines could be stored and which were in easy reach by the two loaders This meant that at least 320 rounds could be carried around the gun. Author D. Nešić (Naoružanje Drugog Svetsko Rata-Nemačka) mentions that the total load consisted of 3,200 rounds. For self-defense, the crew had at their disposal one MG 34 with 600 rounds of ammunition and their personal weapons.

Armor Protection

The Flakpanzer IV’s frontal armor hull protection would have ranged between 50 to 80 mm in thickness, the sides were 30 mm, the rear 20 mm, and the bottom armor was only 10 mm thick. The superstructure frontal armor was 50 mm and its sides 30 mm thick.

The four sidewalls placed to protect the crew and the gun consisted of two 12 mm (or 10 mm, depending on the source) spaced armor plates. The idea behind using two spaced armor plates was that the first would absorb most of the impact and the second plate would stop the round completely. Of course, due to the low armor thickness of only 12 mm, these could only effectively work against small-caliber bullets and shrapnel. Anti-tank weapons could easily pierce this armor.

Crew

The crew of the 2 cm Flakpanzer IV consisted of between five to six crew members. The radio operator and the driver were positioned inside the hull and were fully protected. In the fighting compartment were the two loaders, each on one side of the gun. The gunner was placed behind the gun, while the position of the commander is not clear in the sources. Some sources, such as Walter J. Spielberger (Gepard, The History of German Anti-Aircraft Tanks), mention that the crew of this vehicle consisted of five, which would suggest that the commander probably also acted as the gunner.

The Fate of the Project

Once the prototype was completed, it was presented to a Luftwaffe delegation for inspection on 3rd October 1943. The delegation did not have any objections and the prototype was to be used for initial testing and evaluation. For this, it was driven from Magdeburg to Kummersdorf for testing. During the 6 and a half-hour drive, no major problems were noted on the prototype. Once in Kummersdorf, it was used to test if the whole platform was stable during firing. After firing some 800 rounds using all-four guns, once again no problems were detected. Guderian was generally satisfied with its design and ordered it to be put into production, with 20 vehicles per month to be produced beginning in April 1944.

This was not to be, as, on 21st December 1943, it was decided to instead rearm this vehicle with the more powerful 3.7 cm Flak 43 anti-aircraft gun. For this reason, the 2 cm Flakvierling armed Panzer IV project was temporarily canceled, though revived later with the Wirbelwind project, and Krupp was instructed to focus on the 3.7 cm armed Flakpanzer. Krupp simply reused this prototype and armed it with the 3.7 cm gun. This would lead to the creation of the Möbelwagen, of which more than 200 would be built and which would see extensive action up to the war’s end.

Conclusion

The first Flakpanzer IV prototype, while built relatively quickly and with a satisfactory overall design that satisfied the officials, would not be accepted for service. This was not due to some flaws in the design, but due to the need for a more potent weapon than the 2 cm anti-aircraft gun. Unfortunately, the folding wall solution offered little protection for the crew operating the gun and the time needed to set up the whole system would have taken too long to effectively fight back against any sudden enemy attack. This would later become apparent with the Möbelwagen, which led to the creation of turrets for the next designs, the Wirbelwind and Ostwind.

Specifications
Dimensions (l-w-h)	5.92 x 2.95 x 3.25 m
Total weight, battle-ready	25 tonnes
Crew	5 (Commander/Gunner, Two Loaders, Radio Operator, and Driver)
Propulsion	Maybach HL 120 TR(M) 265 hp @ 2,600 rpm
Speed (road/off-road)	42 km/h, 25 km/h (cross-country)
Range (road/off-road)	210 km, 130 km (cross-country)
Primary Armament	2 cm Flakvierling 38
Secondary Armament	7.92 mm MG 34
Elevation	-10° to +100°
Armor	10 to 80 mm

 

Sources

• K. Hjermstad (2000), Panzer IV Squadron/Signal Publication.
• Engelmann-Scheibert, H. A. Koch, O. W. v. (1978) Renz Flak Auf Dem Gefechtsfeld Podzun-Palla-Verlag
• D. Nešić, (2008), Naoružanje Drugog Svetsko Rata-Nemačka, Beograd
• P. Chamberlain and H. Doyle (1978) Encyclopedia of German Tanks of World War Two – Revised Edition, Arms and Armor press.
• Walter J. Spielberger (1982). Gepard The History of German Anti-Aircraft tanks, Bernard & Graefe
• Ian V. Hogg (1975) German Artillery of World War Two, Purnell Book Services Ltd.
• T. L.Jentz and H. L. Doyle (1998) Panzer Tracts No.12 Flak selbstfahrlafetten and Flakpanzer
• T. L.Jentz and H. L. Doyle (2010) Panzer Tracts No. 12-1 – Flakpanzerkampfwagen IV and other Flakpanzer projects development and production from 1942 to 1945.
• T. L.Jentz and H. L. Doyle (2002) Panzer Tracts No. 20-2 Paper Panzers
• Walter J. Spielberger (1993) Panzer IV and its Variants, Schiffer Publishing Ltd.
• D. Doyle (2005) German military Vehicles, Krause Publications.

German Reich (1945)
Self-Propelled Anti-Aircraft Gun – Possibly 1 Prototype Built

In the later stages of the Second World War, the Germans lost control over the skies and their ground forces had to endure extensive enemy air attack raids. The use of self-propelled anti-aircraft guns (SPAAG) based on half-track chassis offered some way to fight back, but these were themselves highly vulnerable, as they lacked proper armor protection. A SPAAG based on a tank chassis was more desirable. Starting from 1944, the German focus was on producing vehicles based on the Panzer IV chassis. The vehicle known as the Ostwind (Eng. Eastwind) was one of them, armed with a single 3.7 cm anti-aircraft gun placed in an open-topped turret. In the hopes of further increasing its firepower, the Germans tested the installation of two 3.7 cm guns in a modified turret which led to possibly the creation of a single Ostwind II prototype.

A Brief History of the Flakpanzer IV Ostwind

The first real effort to create a self-propelled anti-aircraft vehicle based on a tank chassis, known as a Flakpanzer in German, was the Flakpanzer 38(t). While it was built in some numbers, its design was unsuccessful given the weak firepower, lack of a fully protected turret, and its overall small size. The Panzer IV chassis was deemed more suitable for this task. The first such vehicle, known as the Möbelwagen to its crews, while having a good gun, suffered from the same problems as the previous vehicle. It needed time to properly set up for firing, which reduced its combat effectiveness. For these reasons, the German Army focused on developing a Flakpanzer based on the Panzer IV having a fully rotating and protected turret. This would lead to the creation of two similar vehicles. The first introduced was the so-called Wirbelwind, armed with four 2 cm anti-aircraft guns. The second vehicle was the Ostwind, which was quite similar in appearance, being armed with a single 3.7 cm anti-aircraft gun. Both vehicles were quite simple in design and simply replaced the original Panzer IV turret with an open-top turret with the main gun placed in it.

Unusually, the Ostwind, similar to the Wirbelwind, was developed and built by the German Army itself, without the inclusion of any commercial firms. Due to the worsening economic situation, the use of newly produced tank chassis was limited at best, so repaired and returned from the front chassis had to be reused for this project. While vehicles such as the Ostwind were in great demand, there were huge delays in production, which hindered its introduction to service. By the time the war ended, only between 6 and 43 such vehicles are believed to have been built, seeing limited combat action.

An Improved Model

The general development history of the Ostwind II vehicle is, sadly, quite poorly documented in the sources, with very little information available. What is known is that it was developed by the Ostbau-Sagan workshop from Silesia, which was also involved in the development of the Ostwind Flakpanzer. The main weapon was provided by Gustloff-Werke from Suhl. The request to develop a Flakpanzer armed with two 3.7 cm anti-aircraft guns was given by Adolf Hitler in 1943. During May 1944 several wooded mock-up Flakpanzer projects were presented to a military delegation led by Heinz Guderian. One of these was a wooden mock-up of a Flakpanzer IV armed with 3.7 cm Flakzwilling 43 in its original configuration developed by Alkett. The delegation rejected this project and focused instead on the Wirbelwind, which was also presented at that time. The development of a Flakpanzer IV armed with two 3.7 cm anti-aircraft guns resumed sometime at the end of 1944. The first working prototype was completed only in January 1945. Unfortunately, besides a few drawings, no known photographs are believed to have survived to this day, and questions remain as to if even a prototype was built at all.

Name

The name of this vehicle is often described as being Ostwind II. Due to the lack of information in the sources, it is almost impossible to determine if this was an official or post-war invented designation. This article uses the Ostwind II designation, mostly for the sake of simplicity.

Design

Chassis

The Ostwind II, like its predecessor, would be made using modified Panzer IV chassis. Due to the worsening situation with the war, new chassis could not be spared for projects besides the original tank configuration. The chassis used would have varied depending on what was available on hand. This would most likely have included the Panzer IV Ausf.H and J chassis, but out of necessity, older chassis may have also been used.

Suspension

The suspension and running gear were the same as those of the original Panzer IV, with no changes to its construction. It consisted of eight pairs of small road wheels on each side, with every two pairs suspended by leaf-spring units. There was a front-drive sprocket, a rear idler, and three to four (depending on the model used) return rollers per side.

Engine

The engine was the Maybach HL 120 TRM, which produced 272 hp at 2,800 rpm. The original Ostwind had a weight of 25 tonnes. The improved version would have been heavier than that by about 1.5 tonnes, given the extra weight of the main armament. The new crew member should also be included, but also any additional spare ammunition needed to load the two guns. This would likely affect the overall driving performance, but to which extent is difficult to tell without any explicit source.

Superstructure

The upper tank hull was unchanged from the original Panzer IV. The driver’s front observation hatch and the ball-mounted hull machine gun remained the same as well. The installation of the main armament would most likely be a direct copy of the Ostwind, possibly with some minor modifications, such as strengthening the overall construction of the mount, given the extra weight added by the gun and the additional crew member. Two, or even more, in order to cope with the extra weight, metal beams were welded inside the Panzer IV hull to make a stable platform on which the twin 3.7 cm guns were placed.

Armor

Depending on the chassis used for the Ostwind II, there may have been slight differences in armor thickness. In general, the later built Panzer IVs had a maximum frontal armor thickness of 80 mm. The sides were much thinner, at 30 mm, while the rear was 20 mm thick.

Turret

The Ostwind II turret design would have been quite similar to the previous version in visual appearance, with some differences. The turret was open-topped, in order to provide a better view of the surroundings and to reduce overall construction costs. This would have also helped remove the gun fumes properly, as the Germans never properly developed a full-enclosed anti-aircraft turret with an adequate ventilation unit. The turret consisted of 12 welded armor plates. Due to the new gun and the additional crew member, its overall internal layout and its size had to be changed slightly. In addition, as the two guns were placed side by side, two new openings to the front armor had to be made. There would also be a small hatch for the gun operator’s sight, placed on the right front side of the turret.

The turret traverse mechanism would most likely be a copy of the one used on the Ostwind, which is itself poorly documented. A steering rod was used to connect the twin Flak guns’ traversing mechanism and the Panzer IV turret ring. This allowed the crew to move the turret by using the gun traverse. The turret would be placed on a ring-shaped turret base welded to the hull top, with added ball bearings to help with the rotation. It is unknown if the Ostwind II would have the pyramid-shaped sheet of armor welded to the lower part of the front turret. Its purpose was to provide additional protection against any possible ricochets from smaller caliber rounds in the direction of the vehicle’s hull.

The turret armor protection would probably have remained the same as on the first version in order to save time and resources. The armor thickness would have been 16 mm of all-around armor placed at a 30° angle. The secondary sources disagree on the turret armor thickness, as both 16 mm and 25 mm of armor are often attributed. For example, W. J. Spielberger (Gepard, The History of German Anti-Aircraft Tanks) mentions that the armor thickness was originally 16 mm, but later, during production, it was increased to 25 mm. T. L.Jentz and H. L. Doyle (Panzer Tracts No. 12-1 – Flakpanzerkampfwagen IV and other Flakpanzer projects development and production from 1942 to 1945) list that it was 16 mm thick.

Armament

The main weapon used was the 3.7 cm Zwillingflak 43 (also sometimes called Zwillingflak 44). This weapon was basically just two 3.7 cm Flak 43s placed one above the other. Although sharing the same 3.7 cm caliber as the earlier Flak 18, 36, and 37 models, the newer Flak 43 (built by Rheinmetall-Borsig) was a completely different weapon. The primary goal of this design was to be simple to operate and easy to produce. It had a new gas-operated breech mechanism, which was loaded with a fixed loading tray with eight-round clips.

What is somewhat unusual is that this gun was not placed in its original configuration, but instead side by side, with some 30 cm distance between the two barrels. This is odd, as it would have been much easier to just install the gun as it was into the Ostwind II turret. The most obvious reason for this kind of installation was reducing the overall height. With such an over-and-under configuration, in order to load the upper gun, the loader would have to stand up, which would expose him to enemy fire. In addition, with a height of nearly 3 m, the Ostwind’s weakly armored turret was too exposed to enemy fire. Raising the turret height would only increase the chances of being hit by enemy fire. Another reason would have been the difficulty of putting two loaders on the same side in the relatively cramped turret. The side-by-side configuration may have complicated production and development, but would at least offer more effective use of internal turret space.

The gun itself had to be modified in order to fit inside the turret. The lower part of the carriage and the original gun shield were removed. In order to cover the two front embrasure openings, smaller rectangular shields would be placed in front of each gun barrel. In addition, the spent ammunition baskets had to be smaller.

The Zwillingflak 43 could rotate a full 360°, with a range of gun elevation between – 10° to + 90°. The maximum rate of fire was 500 rounds per minute, but 360 was a more practical rate. With a muzzle velocity of 820 mps, the maximum effective ceiling was 4,800 m. The ammunition load is unknown, but in order to feed the two guns, it (at least in theory) had to be increased from the previous version. The Ostwind ammunition load differs between sources, ranging from 400 up to 1,000 spare rounds. It is possible that an ammunition trailer may have been used on the Ostwind II, but how practical it would be in a real combat situation would be questionable. It must not be forgotten that the German economy in 1945 was in a complete state of chaos and ammunition or fuel stocks were in short supply. For self-defense, the crew could rely on the hull-mounted MG 34, retained from the Panzer IV design, and their personal weapons.

Author D. Nešić (Naoružanje Drugog Svetsko Rata-Nemačka) mentioned that the Ostwind II was armed with two 3 cm Flakvierling MK 103 anti-aircraft guns. He also mentioned that the ammunition load was 2,800 rounds. This is most likely erroneous, mistaking it with the Destroyer 45 based on the Wirbelwind. He also mentioned two 3 cm guns, when ‘Flakvierling’ actually means four guns.

Crew

The crew of the Ostwind II would likely consist of a commander, gunner, radio operator, driver, and loader. The driver and radio operator were placed in the vehicle’s hull. For the radio operator, the Fu 5 and Fu 2 radio equipment were provided. In addition, the radio operator also operated the hull-mounted machine gun.

The positions of the remaining crew members are not listed in the sources. But, given its gun main characteristics, their positions can be deduced. The 3.7 cm Flak 43 gunner position was on the right side, with the position somewhere on the right of the turret. As the two guns were placed side by side, the two loaders had to be placed opposite each other. While two loaders would be needed to properly feed the main guns, it is possible that, due to lack of personnel or space, the commander may have acted as the loader on the left side. This would hinder the main command task, but would provide more working room in the otherwise cramped turret. Given the lack of information, this is merely speculation. The commander would be placed on the left rear side of the turret. The working conditions in the Ostwind II turret would be quite difficult due to the lack of working space. This was actually a problem even on the previous Ostwind vehicle, and was never effectively solved.

The Fate of the Project

According to Walter J. Spielberger (Gepard, The History of German Anti-Aircraft Tanks), once the prototype was completed, it was, together with the improved Wirbelwind (known as Zerstörer 45, Eng. Destroyer), transported to the training center at Ohrdruf, in Thuringia. What happened to them after this point is not clear. Due to the chaos and destruction of the late stages of the war, they may have been used as part of an ad hoc unit in order to fight the advancing Allied formations. It is more likely that they did not see any action, given their experimental nature.

It is also important to consider the fact that the whole Ostwind II construction may have also ended in failure. The installation of two 3.7 cm guns in the cramped modified Ostwind turret may have not been possible. It is also possible that the often mentioned prototype did not even have a fully operational turret and was just used to see if the whole installation was even feasible. As such, some, including Hilary L. Doyle, have speculated that not even a prototype was built, alleging Germany’s almost non-existent industrial capacity at the time. H. L. Doyle expressed suspicion that by 1945 the Germans had industrial capabilities to actually build the Ostwind II vehicle, so it seems unlikely that even one fully operational prototype was ever completed.

Other sources, including author D. Terlisten (Nuts and Bolts Vol.13 Flakpanzer, Wirbelwind and Ostwind) mentions a report from Ostbau-Sagan discovered after the war that mentions that some turrets (plural, although the precise number is not listed) for the Ostwind II were completed. D. Nešić, (Naoružanje Drugog Svetsko Rata-Nemačka) mentions that one prototype was built and that a production order for 100 vehicles was given, which did not materialize due to the end of the war.

Overall, for several reasons, the production of the new Ostwind II was not possible. Due to the Allied advance, the Ostabu-Sagan facility had to be evacuated to Teplitz-Schonau in occupied Czechoslovakia. This caused major delays and confusion during the Flakpanzer production. The lack of resources and spare Panzer IV chassis was also a major issue, not to mention the general lack of spare ammunition and fuel at this stage of the war.

Conclusion

The Ostwind II was certainly an interesting Flakpanzer design. It could have provided the Germans with a vehicle with sufficient firepower to be a serious threat to the Allies. In reality, it is not clear if the whole installation was without any mechanical issue. Another problem was its late conception, with a possible prototype being completed at the start of 1945, though even this is questionable. Given the chaotic state of Germany at that time, serial production would not have been possible.

 

Specifications
Dimensions	5.92 x 2.9 x 2.9 m
Total weight,	25 to 27 tonnes
Crew	6 (Commander, Gunner, Two Loaders, Radio Operator, and Driver)
Primary Armament	3.7 cm Zwillingflak 43
Secondary Armament	7.92 mm MG 34
Propulsion	Maybach HL 120 TR(M) 265 HP @ 2,600 rpm
Armor	10 to 80 mm

 

Sources

• K. Hjermstad (2000), Panzer IV Squadron/Signal Publication.
• Engelmann-Scheibert, H. A. Koch, O. W. v. (1978) Renz Flak Auf Dem Gefechtsfeld Podzun-Palla-Verlag
• D. Nešić, (2008), Naoružanje Drugog Svetsko Rata-Nemačka, Beograd
• P. Chamberlain and H. Doyle (1978) Encyclopedia of German Tanks of World War Two – Revised Edition, Arms and Armor press.
• Walter J. Spielberger (1982). Gepard The History of German Anti-Aircraft tanks, Bernard & Graefe
• Ian V.Hogg (1975). German Artillery of World War Two, Purnell Book Services Ltd.
• T. L.Jentz and H. L. Doyle (1998). Panzer Tracts No.12 Flak selbstfahrlafetten and Flakpanzer
• T. L.Jentz and H. L. Doyle (2010). Panzer Tracts No. 12-1 – Flakpanzerkampfwagen IV and other Flakpanzer projects development and production from 1942 to 1945.
• Walter J. Spielberger (1993). Panzer IV and its Variants, Schiffer Publishing Ltd.
• D. Doyle (2005). German military Vehicles, Krause Publications.
  .

German Reich (1944)
Self-Propelled Anti-Aircraft Gun – Possibly Up To 2 Prototypes Built

In the later stages of the Second World War, the Germans lost control over the skies and their ground forces had to endure extensive enemy air attacks. The use of self-propelled anti-aircraft guns (SPAAGs) based on half-track chassis offered some way to fight back, but these were themselves highly vulnerable, as they lacked proper armor protection. A SPAAG based on a tank chassis was more desirable. Starting from 1944, the German focus was on producing such vehicles based on the Panzer IV chassis. This led to the development of the Flakpanzer IV 2 cm Flak 38 Vierling, better known today as the Wirbelwind (Eng. Whirlwind). With its four 2 cm guns, it shot down many Allied aircraft, but by late 1944 standards, something with more firepower was desired and needed. Thus, the Germans developed a new version armed with four 3 cm anti-aircraft guns. The late start of this project meant that only a few prototypes were allegedly created by the war’s end.

The Wirbelwind

The first real effort to create a self-propelled anti-aircraft vehicle based on a tank chassis, known as a ‘Flakpanzer’ in German, was the Flakpanzer 38(t). While it was built in some numbers, its design was unsuccessful given its weak firepower, lack of a fully protective turret, and its overall small size. The Panzer IV chassis was deemed more suitable for this task. The first such vehicle, known as the Möbelwagen to its crews, while having a good gun, suffered from the same problems as the previous vehicle. It needed time to properly set up for firing, which reduced its combat effectiveness. For these reasons, the German Army focused on developing a Flakpanzer based on the Panzer IV with a fully rotating and protected turret. This led to the creation of the Wirbelwind, armed with four 2 cm anti-aircraft guns placed in a simple open-topped turret.

The Wirbelwind was developed and built by the German Army itself, without the inclusion of any commercial firms. Due to the worsening economic situation and in order to speed up its overall production, repaired vehicles and chassis returned from the front were mostly reused for this project. From July 1944 to January 1945, some 100 vehicles (the number differs between sources) would be built. These would see service both on the Western and Eastern fronts, proving to be effective weapons.

Development of the Flakpanzer IV 3 cm Flakvierling

In German Army service, the Wirbelwind was seen as a temporary solution until better-armed self-propelled anti-aircraft vehicles could be developed. By late 1944, a new proposal emerged to simply upgrade the Wirbelwind with more potent weapons. This would lead to the creation of a new vehicle armed with four 3 cm anti-aircraft cannons, known as the Flakpanzer IV 3 cm Flakvierling.

The overall history of this vehicle is quite obscure due to the general lack of information and the late start of the project. In November 1944, Ostbau-Sagan, a small German Army-organized workshop, which was involved in the design and construction of the Flakpanzer IV projects, presented the German Army officials with a new self-propelled anti-aircraft prototype. They reused the Flakpanzer IV (Möbelwagen) replacing its single 3.7 cm armament with four 3 cm Flak 103/38 anti-aircraft guns. This vehicle was used mainly for testing and evaluation. Further development of the project focused more on installing this armament into a Wirbelwind. It is likely that they wanted to reduce the overall design and production time.

Name

The name of this vehicle was Flakpanzer IV 3 cm Flakvierling. It was common for the Flakpanzer IV series to simply add the type and the caliber of its main armament to distinguish them from each other. It is quite common in the sources to see the Zerstörer (Eng. Destroyer) 45 designation attached to this vehicle. It is difficult to establish if this was an official designation or a name given after the war. Regardless, this article will refer to it as the Zerstörer 45 for the sake of simplicity.

Design

Due to the little existing information, the precise internal design of the Zerstörer 45 is unknown.

Chassis

For the construction of the Zerstörer 45, a Panzer IV chassis would have been used. Due to the worsening economic situation, new chassis could not be spared for such auxiliary vehicles. The chassis used would have varied depending on what was available on hand. This would most likely have included the Panzer IV Ausf.H and J chassis, but out of desperation, older chassis may have also been used.

Suspension

The suspension and running gear were the same as those of the original Panzer IV, with no changes to its construction. This consisted of eight pairs of small road wheels on each side, with every two pairs suspended by leaf-spring units. There was a front-drive sprocket, a rear idler, and three to four (depending on the model used) return rollers per side.

Engine

The Zerstörer 45 was to be powered by a Maybach HL 120 TRM which produced 272 hp at 2,800 rpm. While the Wirbelwind weighed some 22 tonnes, the Zerstörer 45 would have been slightly heavier than that. This would likely have affected the overall driving performance, but to what extent is difficult to tell without any explicit source.

Superstructure

The upper tank hull was unchanged from the original Panzer IV. The driver’s front observation hatch and the ball-mounted hull machine gun remained the same as well. The installation of the main armament was more or less a direct copy of the Wirbelwind design, possibly with some minor modifications. The major change to the Panzer IV chassis would be adding a stable firing platform for the main armament, which would be placed on the turret ring. What kind of platform is unknown, but likely to have been similar to that of the Wirbelwind.

Turret

The Zerstörer 45 was more or less just an improved Wirbelwind, so it would have utilized many of the same components. The nine-sided open-topped turret’s overall design would likely have been the same, with some minor changes. It was open to the top in order to provide a better view of the surroundings and to reduce overall construction costs. This would have also helped remove the gun fumes properly, as the Germans never properly developed a full-enclosed anti-aircraft turret with an adequate ventilation unit. Each of these nine-sided plates was built by welding two angled armored plates. The lower plates were angled outwards and the upper ones were angled towards the inside. The angled armor provided some extra protection but, in general, it could only protect the crew from small-caliber weapons or splinters. The upper front armor plate, between the Flak barrels, had a small hatch that could be opened to allow the gunner to see and engage ground targets.

In order to make the construction of this vehicle easier, no extra traverse mechanism was provided. The turret was instead traversed by using the main gun traverse. The new turret was, in essence, just an extended gun shield. The ring-shaped turret base was welded to the hull top. To help with the rotation, ball bearings were added into this base, which made turret movement much easier.

Armor

Depending on the chassis used for the Zerstörer 45, there may have been slight differences in the armor thickness. In general, the later built Panzer IVs had a maximum frontal armor thickness of 80 mm. The sides were much thinner, at 30 mm, while the rear was 20 mm thick.

The turret armor protection would likely have been unchanged from the Wirbelwind, in the hope of saving development time and resources. If this is true, the armor thickness would have been 16 mm of all-around armor, with the top being completely opened. The side and front plates were placed at 21° to 27° angle. The rear plates were placed at a 14° to 20° angle

Armament

The most obvious change introduced on the Zerstörer 45 was the installation of the 3 cm Flakvierling anti-aircraft gun. This weapon was introduced to service (in single barrel version) as the 3 cm Flak 103/38 during 1944. It is also often named as the ‘Jaboschreck’,o which can be translated as terror or fright (Ger. Schreck) of the fast ground attack aircraft (Jagdbomber in German or just Jabo for short). In reality, if it would have lived up to its name is quite questionable. It was built as a combination of the aircraft-based 3 cm MK 103 cannon and the 2 cm Flak 38 mounting, mostly to get it in operational service as soon as possible and to be cheap to produce. In mid-1944, Rheinmetall-Borsig was tasked with the production of some 2,000 guns, in addition to 1,000 guns that were to be built by Gustloffwerke, but only small numbers were produced by the end of the war.

The 3 cm Flak 38 was a gas-operated and fully automatic gun capable of firing at 450 rpm, but the more practical rate of fire was 250 rpm. The 3 cm Flak 103/38 introduced a new belt-fed system which replaced the older 20 round magazine fed system. The maximum firing range at ground targets was around 5,700 m, while airborne targets could be hit at 4,700 m. It had a 360° traverse and -10° to +80° elevation.

Late into the war, a four-barreled version of the 3 cm MK 103, known as the 3 cm Flakvierling, was tested and possibly even built-in smaller numbers. Due to the late introduction, the overall characteristics of this four-barreled version are barely mentioned in the sources. Based on a few available photographs, it was provided with cylindrical-shaped magazines that were fixed to the gun but could be opened to place belt-fed ammunition inside of them. Another interesting feature was that these ammunition magazines were placed above (on the upper) and under (on the lower) guns, not on the side, like for the 2 cm four-barreled version.

Lastly, for self-defense, the crew could rely on the hull-mounted MG 34, retained from the Panzer IV design, and their personal weapons.

Crew

The crew of the Zerstörer 45 would likely consist of a commander/gunner, radio operator, driver, and one or two loaders. The driver and radio operator were placed in the vehicle’s hull. The positions of the remaining crewmembers are not listed in the sources. Given its gun’s main characteristics, their positions can be deduced. The 3 cm Flak38 commander/gunner position was to the rear of the gun. Given the use of a belt-fed system, it is possible that only a single loader would be placed in the turret. This seems plausible, given the general lack of manpower by 1945, but it would have greatly increased the reloading time of the main armament. On the other hand, the prolonged fire interval of the belt-fed system was probably sufficient to destroy or just drive off the attacking aircraft long enough for the crew to reload the main armament. In this case, the commander may have also helped to reload the armament faster. It is also possible that two loaders were placed in the turret too, each responsible for reloading two guns.

The Fate of the Project

According to author Walter J. Spielberger (Gepard: The History of German Anti-Aircraft Tanks), two such vehicles were built by the end of 1944. What happened after that is not clear. It appears that at least one of them was, alongside the Ostwind II, transported to the training center at Ohrdruf in Thuringia. If these vehicles were ever actually fully completed and if there were any defects with the overall design is unknown. Given their late introduction and unavailability of sources, this is unclear. Authors H. F. Duske, T. Greenland and F. Schulz (Flakpanzer IV Wirbelwind and Ostwind) mention that at least 6 ground mounts for the Zerstörer 45 were built. Author D. Nešić (Naoružanje Drugog Svetsko Rata-Nemačka), on the other hand, mentions that only one such vehicle was produced.

Conclusion

The Zerstörer 45 was another German World War Two design that is shrouded in mystery. While some sources claim that at least two were completed, it is not well known if the whole installation was viable. For example, the ground version of the 3 cm cannon, while effective when used against enemy aircraft, was noted to have a number of defects, such as strong vibrations during firing, which affected its precision, something the Germans tried to improve but never truly resolved. Given its late introduction, the chaotic state of Germany was in, with ammunition, manpower, and fuel in short supply. The Zerstörer 45 had great potential to be a good anti-aircraft weapon, at least in theory. In reality, the whole project was undertaken under harsh conditions of 1945 and was simply over-ambitious, without any real chance of getting into mass service.

Specifications
Dimensions (L-W-H)	5.92 x 2.9 x 2.76 m
Total weight, battle-ready	25 tonnes
Crew	5 Commander/Gunner, Two Loaders, Radio Operator and Driver
Propulsion	Maybach HL 120 TR(M) 265 HP @ 2600 rpm
Range	320 km on road; 210 km off-road
Primary Armament	Four 3 cm Flak 103/38
Secondary Armament	MG34 machine gun
Armor	10 to 80 mm

 

Sources

• K. Hjermstad (2000), Panzer IV Squadron/Signal Publication.
• Engelmann-Scheibert, H. A. Koch, O. W. v. (1978) Renz Flak Auf Dem Gefechtsfeld Podzun-Palla-Verlag
• D. Nešić, (2008), Naoružanje Drugog Svetsko Rata-Nemačka, Beograd
• P. Chamberlain and H. Doyle (1978) Encyclopedia of German Tanks of World War Two – Revised Edition, Arms and Armor press.
• Walter J. Spielberger (1982). Gepard: The History of German Anti-Aircraft tanks, Bernard & Graefe
• Ian V.Hogg (1975). German Artillery of World War Two, Purnell Book Services Ltd.
• T. L.Jentz and H. L. Doyle (1998). Panzer Tracts No.12 Flak selbstfahrlafetten and Flakpanzer
• T. L.Jentz and H. L. Doyle (2010). Panzer Tracts No. 12-1 – Flakpanzerkampfwagen IV and other Flakpanzer projects development and production from 1942 to 1945.
• Walter J. Spielberger (1993). Panzer IV and its Variants, Schiffer Publishing Ltd.
• D. Doyle (2005) German military Vehicles, Krause Publications.
• H. F. Duske, T. Greenland and F. Schulz (2005) Flakpanzer IV Wirbelwind and Ostwind, Nuts and Bolts vol.13

German Reich (1943)
Self-Propelled Anti-Aircraft Gun – 1 Mock-up Built

As the Luftwaffe (German Air Force) lost control over the skies over Germany in the second half of the Second World War, it could no longer provide sufficient protection against Allied aircraft. Panzer divisions were especially affected by the lack of cover from fighter aircraft because they were always at the center of the most intense fighting.
The Germans already had copious amounts of half-tracked Self-Propelled Anti-Aircraft Guns (SPAAG) of different calibres and weights (Sd.Kfz.10/4, Sd.Kfz.6/2, Sd.Kfz.7/1, etc). As these vehicles had very limited or no armor, they were vulnerable to enemy fire either from ground or air. The crew needed better protection from small arms fire and artillery/mortar high explosive fragmentation shell shrapnel. A tank-based anti-aircraft vehicle (German: Flakpanzer) could solve this problem, as it would have sufficient armor to resist most ground attacks with the exception of larger caliber guns. They would also provide some protection against air attacks, but even tanks could be destroyed by air ground-attack fire.

Side view of the Flakpanzer 341. Source
Many designs based on different Panzer chassis and weapons were tested and built during the war. The most successful were the ones based on the Panzer IV chassis (Möbelwagen, Wirbelwind and Ostwind), which were built in some numbers but were too late to have a significant impact on the war. One of the major shortcomings of all German Flakpanzers was the lack of a fully enclosed fighting compartment. As all were open-topped (because of easier construction, easier exhaust of gun fumes and the need to produce them as fast as possible), the gun crews were exposed to air attacks.
By the end of the war, the Germans tried to solve this problem by designing and building new Flakpanzers with fully enclosed turrets. One of these was the Flakpanzer based on the Panther tank, best known today as the ‘Coelian’.

History

In May 1943, Oberleutnant Dipl.Ing von Glatter-Götz, responding to the orders of Inspectorate 6, initiated the development of a new series of Flakpanzers based on already existing chassis. The Panzer I and II were outdated or used for other purposes. The Panzer III tank chassis was used for the production of the StuG III and thus not available. The Panzer IV and the Panzer V Panther were considered next. The Panzer IV tank chassis was already in use for several German modifications, so it was decided to use it for the Flakpanzer program. The Panzer V Panther was considered in case even the Panzer IV chassis proved to be inadequate for the task.
The Germans formed a commission for the analysis of the effectiveness of enemy ground attack planes. The report (dated 31st June 1943) stated that, in the case of dive-bombing, the lowest point that the enemy plane reached was 1200 to 1500 m at an angle of 45-80°. Planes using larger caliber machine guns or cannons attacked at an altitude of around 150 to 300 m. The committee suggested that the best way to bring down enemy planes was using direct fire autocannons. To effectively fight the enemy planes, the future Flakpanzer would have to have a fully rotating turret with a high angle of fire and the caliber used should not be lower than 2 cm, with the more powerful 3.7 cm being preferred.
To give the crew the best protection possible and to meet any future Allied developments, the Panther-based Flakpanzer had to have a fully enclosed turret that could be armed with several different proposed weapon configurations. These included the 2 cm Flakvierling, 3.7 cm (either twin or triple configuration), 5.5 cm Flakzwilling and even an 88 mm caliber heavy flak gun. The first proposed design drawings (HSK 82827) were completed by Rheinmetall in late May 1943. The armament consisted of four 20 mm MG 151/20 mounted in a specially designed turret. The elevation of the four guns was -5° to +75°. This proposal was never implemented, mostly due to the weak armament by the standards of 1944.
On the 21st December 1943, a Panzerkommision was formed to examine the further development of a Flakpanzer based on the Panther tank chassis. It was decided that the main armament should consist of at least two 3.7 cm caliber anti-aircraft guns. This requirement was later revised to two 5.5 cm Gerät 58 guns. The development of this new weapon had begun in 1943, but due to its complicated design, problems developing the ammunition and the late start of the program, only 3 prototypes were completed by the war’s end.
For the construction of the new turret, Daimler-Benz was chosen. The new turret had to fulfill several set criteria like armor thickness and having an effective traversing mechanism. The armor protection of the turret was to be impressive, with 100 mm frontal armor and 40 mm on the sides. The turret was to be moved by using a hydraulic drive which was powered by the tank’s own engine. The new turret design was to be ready by the middle of 1944, but nothing came from this.

Rheinmetall’s proposed Flakpanzer turret armed with four 20 mm anti-aircraft guns. Source

The Rheinmetall-Borsig “341” design

Unfortunately, being more or less a project only, there is little known information about this Rheinmetall-Borsig design. What is known is that, by the end of 1943, Rheinmetall-Borsig (or its subsidiary, Vereingte Apparatebau AG, depending on the source) began working on its own design for the new Flakpanzer based on the Panther tank chassis. The first drawings of the new vehicle were completed by 23rd May, 1944. One mock-up turret was built and placed on a Panther D and presented to Wa Prüf 6 at Kummersdorf, possibly in early 1945. Due to many reasons, it never went into production and the whole 3.7 cm armed Flakpanzer based on the Panther tank chassis was cancelled in January 1945 in favour of the larger 5.5 cm weapons.

Only one mock-up with a wooden turret was ever built and presented to German army officials. It was never adopted for service, mostly due to the need to focus production on Panther tanks. Source

Name

Depending on the source, there are different designations for this vehicle armed with 3.7 cm anti-aircraft guns. These include Flakzwilling 3.7 cm auf Panzerkampfwagen Panther, 3.7 cm Flakzwilling auf Panther Fahrgestell “341” or, simply, Flakpanzer 341. The designation 341 stands for the two main 3.7 cm guns (Flak or Gerät 341). This article will use the Flakpanzer 341 designation for the sake of simplicity.
It is also best known today under the ‘Coelian’ name. Coelian is actually the third name of Oberleutnant Dipl.Ing von Glatter-Götz, who was greatly involved in the development of the German Flakpanzer program. It is important to note that the Coelian designation was never used by the Germans and was possibly added after the war, like many similar German armored vehicle designations.

Front view of the Flakpanzer 341. The simple flat face of the lower part of the front turret and the angled upper part can be seen. Source: Unknown

What-if illustration of how a Flakpanzer 341 prototype with the later turret design might have looked like. Illustrated by David Bocquelet.

Technical characteristics of the Flakpanzer 341

Due to a lack of information, the precise Flakpanzer 341 technical characteristics are not known in detail.
The Rheinmetall-Borsig Flakpanzer was meant to be built using a new turret designed by the company and mating it with a Panther tank chassis. While sources do not explicitly mention it, it is possible that the chassis used for the production would consist of damaged ones returning from the front for repairs or major overhauls (similar to the Wirbelwind and Sturmtiger) rather than using new ones. The armor of the Panther hull was 80 mm thick at the front and 40 mm on the side and rear. The overall Panther hull would most likely have had only some minor modifications in order to speed up production.
The lower front and side section of the turret had simple flat plates. The top armor was sloped, probably in order to increase protection against air attacks. The rear armor consisted of one large rounded plate. There were at least two hatches on the top and one on the turret rear. Additional ventilation ports would most likely have been added to avoid the accumulation of fumes from the guns. The turret armor thickness was 70 mm, the gun mantlet had 80 mm, while the sides and rear were 40 mm thick. This was less than the Daimler-Benz version with 100 mm of frontal armor. It is interesting to note that, on Hilary L. Doyle’s drawing from the book Panzer Tracts No.20-2 Paper Panzers (dated from May 1944), the turret has a much more angled front armor design. The built mock-up had flat front and side plates, probably as these were easier to build. The turret was to be operated by a hydraulic drive powered by the Panther’s own engine.
For the main armament, twin experimental 3.7 cm (L/77) Flak 341 guns were chosen. Some sources wrongly mention the 3.7 cm Flak 43 as the main armament. The 3.7 cm Flak 341 (3.7 cm Gerät 341) was an improved version of the same caliber anti-aircraft gun which was developed by Rheinmetall during 1944. The development process was too slow and only four prototypes were ever built. The Gerät 341 had a range of 4300 m, with a muzzle velocity of 1040 m per second and a rate of fire of 250 rounds per minute (or 400 to 500 depending on the source, but this was probably the maximum theoretical rate of fire of the two guns). The Flakpanzer 341 3.7 cm gun had a belt ammunition feed mechanism with some 1500 rounds of ammo for both guns. The ammunition would be stored beneath the turret, in the vehicle hull. The Flakpanzer 341 turret had a full 360° of traverse, and the gun could elevate between -5° and +90°. The total weight of the guns and the mount was around 470 kg. The secondary weapon would have been the radio operator’s ball-mounted MG 34 in the glacis plate, with one more possibly mounted on the turret roof.

The Flakpanzer 341 with the guns at high elevation. Source
The crew would consist of four to five crew members. While the sources do not specify the precise role of these crew members, we can assume that it would be more or less similar to other Flakpanzer vehicles. In the Panther hull, there were seats for the driver and radio operator / hull machine gun operator.
The two hatches on top of their positions were unchanged. The remaining crew members would be stationed in the new turret. One (or two) loaders would be positioned on either side of the guns. However, because these were belt-fed, their jobs were much easier than with the earlier magazine feed systems. The commander’s position was behind the gun, and he was also probably the gun operator.
The estimated combat weight was around 40 tonnes. The average weight of Panther tanks (depending on the model) was in the range of 44-45 tonnes. With its 700 hp strong Maybach engine, the Flakpanzer 341’s mobility would most likely have been better than that of the regular Panther tank.
The dimensions of the Flakpanzer 341 would also be similar to those of the regular Panther, with the same length of 6.87 m and width of 3.27 m. The height would be the only exception, at 2.8 m to the top of the turret.

The Daimler-Benz and Krupp Flakpanzer 44 design

During 1944, Daimler-Benz and Krupp were also working on a similar Panther-based Flakpanzer. Their turret design had 60 mm thick front armor. It was armed with two 3.7 cm Flak 44 anti-aircraft guns. This project is somewhat confusing for a few reasons. The existing drawings circulating online of the alleged Daimler-Benz and Krupp Flakpanzer 44 are actually of the Flakpanzer 341 according to Hilary L. Doyle. In addition, despite the best efforts of historians, no solid information about the existence of the above-mentioned Flak 44 anti-aircraft guns could be found. There were two different 3 cm Flak 44 projects, but they progressed very little. In addition, in some sources, the 3.7 cm Flakzwilling 43 is wrongly identified as the Flak 44. It is possible that this variation of the Flakpanzer 341 design was mistook after the war as a different project. Being developed during 1944/45, when Germany was in a state of chaos and due to the lack of documentation, the impression of another design having been developed could have formed easily. Of course, due to a lack of proper documentation, this is only an assumption at best.

This is the alleged drawing of the Flakpanzer 44. In fact, this is a Flakpanzer 341 with a modified turret. Source

Reasons for cancelling the project

While the idea of a Flakpanzer equipped with a fully enclosed turret, armed with two anti-aircraft guns, based on the Panther was certainly tempting, there were many reasons why this project would not have been very successful. A fully protected turret offered the crew much needed protection from ground and air fire but it also led to a number of issues that had to be resolved. These included potential problems with ammunition feed loading and removing the used shell cases at 90° angles. Due to the low quality of the German propellant in the late part of the war, during firing, a lot of powder smoke and fumes would be produced which could be dangerous for the crew. A dedicated and efficient ventilation system had to be installed.
The turret controls had to be designed and built to quickly respond to crew commands. The main armament was also problematic. Instead of using already produced weapons, the Rheinmetall-Borsig designers decided to use the experimental 3.7 cm Flak 341. which was never adopted for service. In January 1945, Wa Prüf 6 submitted a report in which the 3.7 cm caliber was deemed as insufficient for an anti-aircraft vehicle of the size of the Flakpanzer 341.
Another problem was the acquisition of air targets. In an open-topped turret, this could be easily achieved by the crew by simple observation. In a fully enclosed turret, a specially designed periscope and sights had to be added.
While the fully protected turret offered many potential advantages, it was not easy to successfully design and build one. While, during the war, the Allies used vehicles with fully enclosed turrets, most anti-aircraft vehicles built after the war were open-topped (like the ZSU-57-2 or M42 Duster).
The most obvious reason why the Flakpanzer 341 was canceled was the high demand for tanks on all fronts across Europe. Thus, sparing any Panther tank chassis for roles other than tank and anti-tank versions was out of the question for the Germans.

Conclusion

Despite this, the development of the Flakpanzer 341 continued up to the war’s end. It never received a high priority and only wooden mock-ups were ever built. Even if the war had continued for some time, there was a small chance (if any) that the Panther-based Flakpanzers would have ever been put into production.

This vehicle would have similar dimensions to those of the ordinary Panther tank. Source

Sources

Duško Nešić, (2008), Naoružanje Drugog Svetsko Rata-Nemačka, Beograd
Peter Chamberlain and Hilary Doyle (1978) Encyclopedia of German Tanks of World War Two – Revised Edition, Arms and Armor press.
Walter J. Spielberger (1982). Gepard The History of German Anti-Aircraft tanks, Bernard & Graefe
Walter J. Spielberger (1993), Panther and its Variants, Schiffer Publishing.
Thomas L.J. and Hilary L. D. (2002) Panzer Tracts No.20-2 Paper Panzers, Panzer Tract
Petr C. and Terry G. (2005) Enzyklopadie Deutscher waffen 1939-1945 Handwaffen, Artilleries, Beutewaffen, Sonderwaffen, Motor buch Verlag.
Hilary D. and Tom J. (1997) Panther Variants 1942-1945, Osprey Military
Werner Oswald (2004). Kraftfahrzeuge und Panzer, der Reichswehr, Wehrmacht und Bundeswehr ab 1900, Motorbuch Verlag,

3.7 cm Flakzwilling auf Panther Fahrgestell “341” specifications
Dimensions	6.87 x 3.27 x 2.8 m
Total weight, battle ready	Around 40 tons
Crew	4-5 (Gunner/commander, loaders, driver and radio operator)
Armament	Two 3.7 cm Flak 341 guns with 360 degree traverse
Armor	Hull front 80 mm, side and rear 40 mm, Turret shield armor 80 mm, front armor front 70 mm side and rear 40 mm
For information about abbreviations check the Lexical Index