"Furniture Truck", "Whirlwind" and "Eastern Wind"

The Flakpanzer 38(t) SPAAG that was put into production in late 1943 was treated as only a temporary fix until a more effective SPAAG could be developed for tank units. German designers analyzed a number of possibilities and chose one. The production of the new vehicle began quickly, and in March of 1944 the German army received the first 3,7 cm Flak 43 auf Pz.Kpfw. IV (Sf), better known as Flakpanzer IV (3.7 cm Flak 43). These vehicles and their descendants were in high demand on the front lines due to the loss of air superiority.

"Furniture truck"

The choice of chassis was an issue during the development of a new SPAAG. The light PzI and PzII tanks were immediately rejected, as they were no longer in production. The Pz.Kpfw.38(t) was also unsuitable. Even though it was still in production, it could carry nothing heavier than a single 20 mm gun. The PzIII chassis was more suitable, but all of them were used to make StuG III and StuH 42 assault guns. The PzIV was finally selected. No new vehicles were produced, but rather repaired chassis were used.

The four-barreled Flakvierling 38 gun system was chosen as one of the most effective weapons against low flying aircraft. A prototype designated 2 cm Flakvierling 38 auf Pz.Kpfw. IV (Sf) was produced in September of 1943. The conversion was very simple. Like on the Flakpanzer I, the AA gun was simply installed on the top of the hull instead of a turret. It was covered with four 10 mm thick armoured screens on each side. This protection was in effect only on the move: the shields had to be flipped down before opening fire, and only the gun shield protected the crew. Another drawback of this design was the significant height. As a result, this type of SPAAG was not mass produced, but it was a stepping stone towards new SPAAGs.

Prototype of the 2 cm Flakvierling 38 auf Pz.Kpfw.IV (Sf) in travel mode.

Prototype of the 2 cm Flakvierling 38 auf Pz.Kpfw.IV (Sf) with the front shield open.

Prototype of the 2 cm Flakvierling 38 auf Pz.Kpfw.IV (Sf) in combat mode.

In December of 1943 the 2 cm Flakvierling 38 auf Pz.Kpfw. IV (Sf) prototype, nicknamed Moebelwagen (furniture truck) due to its tall angular shape, was shown to Hitler and Speer. The result of the demonstration was an order given to Krupp to improve the design.

Moebelwagen in travel mode with raised shields.

The designers tried to reduce the height of the vehicle. To achieve this, the gun was not merely installed on the roof of the turret platform, but sunken in by 250 mm. The gun system was replaced with the single barrel 37 mm Flak 43. The vehicle kept its angular form. As with the first vehicle, the walls could be deployed downwards, but this time the designers added the ability to lock them at a 30 degree angle to additional trapezoidal armoured plates that protruded from the front and rear walls. This permitted the vehicle to fire at airborne targets while leaving some semblance of protection for the crew.

The improved SPAAG was accepted into service as the 3,7 cm Flak 43 auf Pz.Kpfw. IV (Sf) (aka Flakpanzer IV (3,7 cm Flak 43) or Sd.Kfz. 161/3). A rank and file soldiers could get mixed up in all of these designations, so the vehicle received the same name as its prototype: Moebelwagen.

Production was set up at Deutsche Eisenwerke in Duisburg. This factory only performed the final assembly. The armoured superstructure was produced by Krupp at Essen, the PzIV chassis initially came from Krupp-Gruson, but later from the Deutesche Rorenwerke company in Muelheim. The PzIV Ausf.H chassis was used at first, and later the Ausf.J. The AA guns were produced by the Rheinmetall-Durkopp-Simson factory in Suhl. 

The first 20 Sd.Kfz. 161/3 was expected in February of 1944, and a production rate of 30 vehicles per month after that, but the assembly was bottlenecked by the availability of the chassis. The first 20 Moebelwagens were only delivered in March of 1944. 240 SPAAGs of this type were completed by March of 1945. Production only reached the expected volumes in the summer of 1944.

The hull underwent minimal changes during conversion. The hull machine gun was removed, now the hull gunner was just a radio operator and serviced the FuG 5 radio. Since several variants of the PzIV were used for conversions, the armour was different: the front could be 50-80 mm thick, the sides 20-30 mm thick, the rear was 20 mm thick. If the hull was covered in Zimmerit anti-magnetic paste then it was preserved, but Zimmerit was not applied to the superstructure.

An early Sd.Kfz. 161/3.

The open top superstructure was composed of two 12 mm plates sandwiched together with a small space in between on the first 20 vehicles. One later vehicles the thickness of the plates was reduced to 10 mm. Monolithic 25 mm thick plates were used after the 46th vehicle, making production much simpler.

A late production Sd.Kfz. 161/3.

The superstructure contained a 37 mm Flak 43 AA gun. It could be depressed to -6 degrees, elevated to +90 degrees, and had full traverse. The gun kept its shield, but it was trimmed on the right side. 416 rounds of ammunition were kept: HE and AP weighing 623 and 658 grams respectively. The theoretical rate of fire was 180 RPM, but in practice was not above 150 RPM. The maximum range was 6500 m and maximum target height was 4800 m. The gun was equipped with a Schwebekreis-Visier Erdzielfernrohr 3×8 sight (the same sight was used on the other SPAAGs on the PzIV chassis).

Auxiliary armament consisted of two MG 34 or MG 42 machine guns and one MP-40 SMG stored in the fighting compartment. The crew of the Sd.Kfz. 161/3 numbered six men (commander, two gunners, loader, driver, radio operator).

Sd.Kfz.161/3 in fighting position.

Sd.Kfz.161/3 in fighting position.

"Whirlwind"

The Sd.Kfz.161/3 was produced for a long time and in notable amounts, but it was not entirely satisfactory. The placement of the gun in an immobile superstructure was not ideal. A logical evolutionary step would be to equip them with rotating armoured turrets, even ones open from above (this removed the issue of ventilation and made watching the skies much easier). This would improve protection for the crew. Requirements for the new SPAAG were composed by the chief inspector of the tank forces, General Guderian: an open topped rotating turret capable of fitting in 3-4 crewmen, effective range of up to 2000 meters, a dual (or more) barrelled gun system, height of less than 3 m, and the ability to carry enough ammunition to fight for two days.

The development of the SPAAG was performed by Krupp-Druckenmuller (overall layout) and Daimler-Benz (turret). Since the effective range did not have to be great, the 20 mm caliber was sufficient, and the quad 20 mm Flakvierling 38 was used once more.

Wirbelwind turret from above.

The nonagonal welded turret was composed of armour plates 16 mm thick in the upper part and 30 mm thick in the lower. The turret ring diameter was the same as that of the PzIV, which made conversion into a SPAAG much easier. The turret was only 1050 mm tall, thanks to which the designers managed to meet Guderian's requirements (overall height of 2760 mm). Four crewmen were located in the turret: the commander, a gunner, and two loaders. Two mode (driver and radio operator/hull gunner) were located in the driver's compartment. The turret was equipped with a hydraulic drive (traverse speed of 60 deg/s) and a manual backup (28 deg/s).

Sd.Kfz.161/4.

The Flakvierling 38 had a theoretical rate of fire of 1800 RPM, but the practical ROF was much lower: 800 RPM. The maximum range was 4800 m, the maximum target height was 3700 m. The vehicle carried 3200 rounds of ammunition: fragmentation (132 g) and AP (148 g). The SPAAG retained its hull gun. The machine gun had 1350 rounds of ammunition available.

A prototype was demonstrated to Guderian in late May of 1944, and later shown to Hitler. The vehicle had a great impact, which was confirmed during proving grounds trials at Kummersdorf. The SPAAG was accepted into service as the 2 cm Flakvierling 38 auf Pz.Kpfw. IV (Sf), or Flakpanzer IV (2 cm Flakvierling 38), or Sd.Kfz. 161/4. The vehicle also had an official nickname: Wirbelwind (whirlwind).

Wirbelwind in firing position.

Unlike the Moebelwagens, production was given not to industry, but to the repair workshops of the 15th Reserve Tank Battalion located in Sagan (modern day Żagań). The "Kommando Ostbau-Sagan" production facility was organized here, numbering about 80 men headed by Lieutenant Rutard Fitzner. Hans von Seher-Toss became the chief engineer.

A Wirbelwind assembly plant in Sagan.

Initially an order for 80 Wirbelwinds was made, but the order was increased to 130 units in September of 1944 and to 200 in March of 1945. Only 105 were actually produced, some of them in Teplice where Kommando-Ostbau-Sagan was evacuated in early January of 1945. The Flakvierling 38 guns arrived from Ostmark-Werke, a former Vienna arsenal that became a subsidiary of the Hermann-Goering-Werke company after the Anschluss.

Components for the Sd.Kfz.161/4 turret were supplied by the Deutsche Rohrenwerke company. Assembly was produced at FAMO in Breslau (modern day Wroclaw), after which they were shipped to Sagan for installation on the tank chassis. The chassis was somewhat improved: a firewall was installed to protect the driver's compartment from the ammo rack. A floor above the fuel tank was also installed. The fuel tank was moved towards the driver. Containers for spare 20 mm gun barrels were installed along the walls towards the rear. PzIV Ausf.F-H tanks were used for conversion, but later variants use the Ausf.J as well.

"Eastern Wind"

Another prototype SPAAG was built on the chassis of the PzIV Ausf.J in March of 1944. Conceptually, it was similar to the Wirbelwind, as it had a rotating turret open from the top. However, instead of a 20 mm quad gun it had a single 37 mm Flak 43. The turret also had a different shape: hexagonal instead of nonagonal. It was 1000 mm tall. The prototype took part in firing trials on July 27th, 1944 alongside the Wirbelwind, after which it was sent to the 111th Tank Brigade. Even though the turret was built from 10 mm thick mild steel, the SPAAG took part in the Ardennes offensive within the 1st SS Tank Division.

The vehicle was accepted into service as the 3,7 cm Flak 43 auf Pz.Kpfw. IV (Sf) or Flakpanzer IV (3,7 cm Flak 43). An official nickname was also assigned: "Ostwind" (Eastern Wind).

Ostwind SPAAG.

100 Ostwinds were ordered in September of 1944. Deliveries began in December. Production was set up at the Deutsche Rorenwerke factory. The PzIV Ausf.J chassis came from the Krupp-Gruson factory. Final assembly took place at the Deutsche Eisenwerke factory in Duisburg. 43 vehicles were assembled before March of 1945: 7 of them on new chassis, 36 on chassis that were repaired.

Production Ostwinds had a 1900 mm wide turret ring, same as the Tiger. The turret, assembled from 16 mm thick plates, was moved slightly forward compared to the Wirbelwind, which prompted a relocation of the radio operator's hatch.

The Ostwind carried 1000 rounds of ammunition. The ballistic characterisics and available ammunition were the same as on the Moebelwagen.

Prototypes

In addition to mass production vehicles, the PzIV became a basis for the assembly of several SPG prototypes. The 30 mm quad 3 cm Flakvierling 103/28 gun was tested by Kommando-Ostbau-Sagan in December of 1944. The vehicle was codenamed "Zerstörer 45" (destroyer 45). Some researchers claim that five production "destroyers" were assembled in addition to two prototypes.

Kommando-Ostbau-Sagan built two "Ostwind II" SPAAGs with 37 mm Flakzwilling 44 guns developed by Gustloff-Werke. They were later assigned to the reserve AA gun battalion (Flakpanzer Ersatz und Ausbildungs Abteilung) in Ordurf.

The last SPG built on the PzIV chassis was the Flakpanzer IV (3cm) "Kugelblitz" (ball lightning). It had a completely enclosed 3-man turret 600 mm tall which housed dual 3 cm Flak 103/38 guns. The vertical aiming angles were from -5 to +80 degrees, the range was 5700 m. The maximum target height was 3500 meters. The SPAAG carried 1200 rounds of ammunition.

The first five "lightnings" were planned for September of 1944, by December 30 were expected monthly. However, the crisis in German manufacturing delayed production until January of 1945. Various sources state that between 2 and 5 vehicles were completed.

Use in battle

Flakpanzer IV vehicles of all types were used in antiaircraft tank platoons formed to TO&E K.St.N.1196: eight SPAAGs in two groups of four. Initially all platoons were formed with Moebelwagens. The composition changed when the Wirbelwind entered production: now one group was armed with this type of SPAAG, the other retained its Moebelwagens.

In practice, the platoons were equipped with whatever was at hand. The pedantic Germans could not stand this kind of disorder and on February 1st 1945 introduced TO&E 1196a that outlined three types of platoons: Pz.Flak-Zug Ausf. A (four each Moebelwagens and Wirbelwinds), Pz.Flak-Zug Ausf. B, (eight Wirbelwinds) and Pz.Flak-Zug Ausf. A (eight Moebelwagens). On April 1st, 1945, TO&E K.St.N. 1196fG (freie Gliederung - free structure) that allowed eight Ostwinds and three Sd.Kfz.7/1: 8 ton halftracks with quad 20 mm Flakvierling 38 guns.

Moebelwagen on the move. Northern France, summer of 1944.

The first Moebelwagens arrived in the 9th, 11th, and 116th Tank Divisions that fought in Normandy. Each received a full platoon (8 SPAAGs). In July the 6th and 19th Tank Divisions on the Eastern Front received these vehicles, as well as the Fuhrer's escort brigade. Tank brigades, "firefighter teams" formed in a hurry, had the priority for receiving Sd.Kfz.161/3 vehicles in August-September. Each brigade only had one tank battalion with a platoon of SPAAGs. The 101st, 102nd, 103rd, 105th, and 106th brigades had 8 Sd.Kfz.161/3 each, the 107th and 108th had 4, the 111st, 112th, and 113th had mixed platoons (four Sd.Kfz.161/3 and four Sd.Kfz.161/4 each).

Tank brigades fought on both the Eastern and Western fronts, but were gradually disbanded and turned into reinforcements for tank divisions. In late 1944 Moebelwagens appeared in several Panzergrenadier divisions on the Western front: 15th (2 SPAAGs) and 25th (4 SPAAGs). A small amount of Sd.Kfz.161/3 ended up in Italy in the 26th and 29th Tank and 90th Panzergrenadier Divisions. The latter received four Moebelwagens and four Wirbelwinds.

Camouflaged Wirbelwind on the move.

Four Wirbelwinds apiece were used by the 2nd, 9th, and 11th Training Tank Divisions of the Wehrmacht, as well as the 1st, 2nd, 12th, and 17th SS Tank Divisions. In most of these cases they were supplemented by the Sd.Kfz.161/3, but the 17th SS TD instead had six Flakpanzers 38(t). The Wehrmacht 17th TD had to make do with only three Wirbelwinds. In addition, the Sd.Kfz.161/4 were included in AA platoons in anti-tank battalions: 510th, 559th, 560th, 653rd, 654th, and 655th. They each received four Sd.Kfz.161/4, except the 654th, which had seven. Most of these battalions fought on the Western front, and only the 653rd fought in the east. After the Ardennes offensive, the 560th battalion was moved to Hungary. Two Wirbelwinds were assigned to the 217th Assault Gun battalion, also fighting in the West.

Wirbelwind from the 509th Heavy Tank Battalion, Hungary.

The same vehicle from another angle.

One of Germany's most serious combat units at the end of the war was the Heavy Tank Battalion. Armed with Tigers or King Tigers, they could effectively hold off the enemy's tank spearhead. However, this "wonder weapon" needed reliable protection from above. Standard AA platoons (four Sd.Kfz.161/3 and four Sd.Kfz.161/4) were attached to heavy tank battalions. The 503rd, 506th, 509th Wehrmacht battalions and 501st and 503rd SS battalions received these platoons.

American soldiers inspect a destroyed Wirbelwind.

Information on the Ostwind's combat career is sparse. Some amount of these SPAAGs took part in the Ardennes offensive. At least one Ostwind was recorded as lost.

Ostwind ready to fire.

In addition to front line units, the SPAAGs were used by reserve units, most notably the reserve SPAAG battalion formed in Ordurf in 1944. One of its companies was composed of three platoons. One had five Wirbelwinds, one had five Ostwinds, the third had the experimental Kugelblitzes. The reserve battalion's SPAAGs took part in the last ditch fighting for Berlin.

Ostwind and Wirbelwind in battle position.

The Flakpanzer IV proved itself to be an effective AA weapon for tank units, whether on the march or during pauses. They combined tank-like mobility and firepower that could repel low flying fighters and ground attack aircraft. While the Moebelwagen's armament was far from perfect, the turrets on the Wirbelwind and Ostwind significantly improved protection for the crew and also increased effectiveness of fire thanks to the powered traverse.

A Moebelwagen captured by the British. It has a field modification: a cutout in the front shield to fire at ground targets.

A Wirbelwind captured by Soviet forces.

The main task performed by the Wirbelwind was screening fire in the way of attacking aircraft. A high rate of fire and four barrels created a wall of fire in front of attacking fighter-bombers or ground attackers. However, this kind of effectiveness was a bane of the AA gunners: they were priority targets for enemy aircraft, which aimed to knock them out first and then deal with the tanks without issue. The SPAAGs were also occasionally used against ground targets.

Original article by Andrei Haruk.