the Wirbelwind anti-aircraft tank, source: Flickr.com with permission of the publishing user, edited

Origins of the Flakpanzer

By 1944, the Luftwaffe had long since ceased to be capable of providing German ground forces with adequate protection against direct enemy air attack. The Germans were therefore desperately in need of self-propelled anti-aircraft weapons to protect troops and vehicles both on the move and in combat. Armoured units in particular lacked anti-aircraft means capable of keeping pace with them across the most demanding terrain. What was needed were vehicles with a fully tracked chassis and, ideally, a reasonable degree of armour protection. The answer was the so-called Flakpanzer — tank chassis fitted with anti-aircraft weapons. Of the available chassis, the one from the Panzer IV appeared the most suitable for this purpose.

Following the experience gained with the Möbelwagen anti-aircraft tank, the newly developed vehicles were to have a rotating fighting turret to protect the gun crew even during firing. For reasons that are not entirely clear, the ordnance office decided not to commission the new Flakpanzer from a commercial firm, but instead assigned the task to the repair and training unit Panzer Ersatz und Ausbildungs Abteilung 15, based in the town of Sagan (present-day Żagań in Poland). Within this unit, the so-called Kommando Ostbau Sagan was formed, which produced two design proposals for converting used tank chassis into modern anti-aircraft tanks. One was the Wirbelwind described below; the other, named Ostwind, is covered in a separate article.

By August 1944, the technical documentation for a vehicle armed with four 20 mm guns in a fully rotating nine-sided turret was complete. The Army immediately placed an order for 80 such tanks, but soon increased this to an even 200. The new vehicle received the official designation Flakpanzerkampfwagen IV (2cm Flak 38 Vierling) and the ordnance code Sd.Kfz. 161/4. It passed into the history of the Second World War, however, under its battle name Wirbelwind — literally "whirlwind".

a Wirbelwind anti-aircraft tank knocked out by the Americans, source: Flickr.com, Public domain, edited

Description of the Design

Production of these vehicles could take place directly within the unit rather than in a factory, since it was less a matter of manufacturing from scratch and more one of assembly — putting together already finished components. The basis was provided by older, previously used Panzer IV chassis of the Ausf. G, H, and J variants. Unlike the older Möbelwagen, the original tank hulls required no significant modification. The tanks were simply stripped of their combat turrets, and a new turret was fitted into the original turret ring. This turret was manufactured and supplied to Ostbau Sagan by the firm Deutsche Röhrenwerk. It was nine-sided in plan, elongated at the rear, and constructed from armour plate only 16 mm thick, which was angled for greater ballistic protection. The turret was open at the top so that the crew had a clear view of the sky and could easily spot — or even hear — an approaching enemy aircraft.

Inside the new turret was mounted the quadruple-barrelled 2 cm Flakvierling 38. This weapon consisted of four automatic 20 mm Flak 30 anti-aircraft guns, giving it an extraordinary theoretical rate of fire of 1,800 rounds per minute (4 × 450). The practical rate of fire was "only" around 720 to 800 rounds per minute — but even this is a deeply impressive figure. The high rate of fire was invaluable precisely when engaging fast-moving targets. The gun could rotate together with the turret through a full 360 degrees. Vertical elevation ranged from -10° to +100°, so the weapon could easily be used against ground targets as well. Secondary armament consisted of an MG 34 machine gun in the front hull plate, retained from the original tank.

The Wirbelwind's crew consisted of five men. The driver and radio operator were seated in the hull front, just as in a standard Panzer IV. The remaining three crewmen had their stations in the turret. Directly behind the gun sat the gunner, who also appears to have acted as the vehicle commander. On either side of the weapon sat two loaders, each responsible for two guns on their respective side — keeping them both supplied was certainly a full-time occupation. The vehicle's ammunition supply comprised 3,200 rounds of 20 mm and 1,350 rounds of machine gun ammunition.

another Wirbelwind anti-aircraft tank knocked out by the Americans, source: Flickr.com, Public domain, edited

The Wirbelwind's powerplant was inherited along with the tank chassis — a Maybach HL 120 TRM twelve-cylinder petrol engine with a displacement of 11.9 litres and a maximum output of 300 horsepower. The six-speed Zahnradfabrik SSG 76 Aphon gearbox was likewise carried over from the original battle tank. The Wirbelwind weighed approximately 22 tonnes and was capable of reaching 38 km/h. Its operational range was around 200 km on roads and 130 km cross-country.

Production of this vehicle began in September 1944. Of the 200 ordered, however, only 122 were delivered before the end of the war. Wirbelwind anti-aircraft tanks were organised into anti-aircraft platoons of either four or eight vehicles and assigned to various armoured formations, where they were often combined with the older Möbelwagens. Operational experience with the vehicle was generally very positive, and the rotating turret proved to be a significant improvement over the older Möbelwagen.

Technical Specifications

ARTICLE
CONTENTS:

ORIGINS

DESIGN

TECHNICAL DATA