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WW2 German Tank Destroyers

7.62 cm F.K. 36(r) auf gp. Selbstfahrlafette Sd.Kfz. 6/3

ww2 german tanks Germany (1941) – Self-propelled anti-tank vehicle, Number built: 9

During the war, the Germans encountered ever increasing numbers of strong enemy armor. Due to a general lack of numbers of their own tanks, they were often forced to field improvised anti-tank vehicles. These were mostly based on obsolete tank chassis, such as the Marder series, and armed with good anti-tank guns. In some rare cases, half-tracks were also employed in this manner. One such vehicle was the 7.62 cm F.K.(r) auf gp. Selbstfahrlafette (Sd.Kfz. 6/3) developed during late 1941. While the increase in firepower was welcome, these vehicles had a number of defects which ultimately lead to a small production run of only 9 vehicles.

The 7.62 cm F.K.(r) auf gp. Selbstfahrlafette (Sd.Kfz. 6/3). Source: https://forum.warthunder.com/index.php?/topic/506317-sdkfz-63-diana-soviet-guns-for-the-afrika-korps/

History

From 1941 onwards, on the Eastern Front, the Germans were starting to encounter tanks like the T-34 and KV series, which their tank and anti-tank guns struggled against. The situation in North Africa was not better either, as the British employed tanks such as the Matilda II, which were difficult to effectively deal with. The 7.5 cm PaK 40 towed anti-tank gun that was slowly entering service from the end of 1941 was able to successfully destroy these vehicles at long ranges. However, its main issue was its general lack of mobility, being a heavy towed gun. In the vast expanses of North Africa, a self-propelled anti-tank vehicle could offer a number of advantages, being able to quickly respond to enemy armor movements. It was for this reason that, in August 1941, the Germans began developing such a vehicle. It was meant to reinforce the German forces (Deutsches Afrikakorps DAK – German Africa Corps) fighting in North Africa.

For the initial tests, truck or half-track chassis were proposed. Regarding the armament, the Germans had two options to choose from, either the 5 cm PaK 38 or the captured Soviet 7.62 cm F.K. 36(r). The 7.5 cm PaK 40 was still under development at this time and far from entering service. Ultimately, the choice was cast in favor of the stronger and larger 7.62 cm F.K. 36(r) gun. According to the original plans, if the whole assembly proved viable, a limited production run of some 20 vehicles was to be carried out. This was ultimately changed to only 9 vehicles for unknown reasons. At the end of August, the German Army High Command (Oberkommando des Heeres) announced that, due to the urgent need for such vehicles, the chassis of a modified Sd.Kfz. 6 half-track was to be armed with a 7.62 cm F.K. 36(r).

The Sd.Kfz. 6 5-ton half-track was one of several similar half-track vehicles employed by the Germans during the war. It was developed back in 1934 by Buessing-NAG with the intention of providing the Pioniere (German Army engineers) with a vehicle for towing pontoon bridges and other equipment and the standard German 10.5 cm field howitzers. During the war, these were modified and used as self-propelled anti-aircraft vehicles. Depending on the role it was to perform, it received a slightly modified designation. The regular engineer version was named Sd.Kfz. 6, the artillery towing version was the Sd.Kfz. 6/1 and the later anti-aircraft version was the Sd.Kfz. 6/2. While the half-track had a somewhat complicated suspension which consisted of 5 (later increased to 7) overlapping and interleaved double road wheels, its performance was deemed satisfactory. Like many other German vehicles, there were simply never enough of them to fulfill the Army’s needs. When the production ended in 1943, some 3,122 had been built.

An Sd.Kfz. 6 5-ton half-track towing the standard 10.5 cm leFH 18. Source: Wiki

The main gun for this modification was actually a Soviet 76.2 mm M1936 (F-22) divisional gun. Such guns were captured in huge numbers during the initial months of Operation Barbarossa in the East. After a brief assessment of the gun’s characteristics, the Germans were satisfied with its performance. The gun was given to the army for use, under the name 7.62 cm F.K. (Feldkanone) 36(r) (also sometimes designated as Feldkanone (FK) 296(r)). It was initially used in its original field gun role, but very soon it became clear that it possessed great anti-tank capabilities. As this was a captured weapon, the German Army High Command also issued orders to collect as much armor-piercing and high-explosive ammunition as possible. These were to be then allocated to the unit that was to be equipped with this gun.

The 7.62 cm M1936 (F-22) was a Soviet divisional gun. Source: Wiki

Testing the Prototype

Once the first prototype was completed by Alkett sometime during late August or early September, it was transported for testing at the secret research center in Kummersdorf during September 1941. The prototype had a very basic design, with a large thinly armored structure placed on the former cargo bay of the half-track chassis. The front driver’s compartment was unchanged. The gun was placed inside this new box-shaped firing compartment. In order to fit inside, its trailing legs were shortened.

A series of evaluation and firing tests were conducted on 10th September. A few days later, Wa Prüf 6 (the tanks and motorized equipment design office) personnel made a report of its overall performance. In short, the report described that some 44 high-explosive and armor-piercing rounds were fired from the prototype vehicle at different elevations and traverse angles. No major issues were detected with the gun assembly. The half-track chassis also proved to be up to the job, as it could withstand the recoil of the 7.62 cm gun.

The 7.62 cm F.K.(r) auf gp. Selbstfahrlafette Sd.Kfz. 6/3 had a laconic overall design, which is quite evident here. It consisted of a box-shaped fighting compartment and the unchanged driver compartment to the front. Given its short and fast development process, this should not come as a surprise. Source: https://www.chaosbunker.de/en/2020/02/07/sdkfz-6-3-diana-for-the-afrikakorps-but-how/

While the overall design was deemed satisfactory, some changes were requested. The prototype was provided with an armored cover for the half-track’s radiator to protect it from damage from firing the gun, but this did not happen. It was proposed that it be removed, likely to save as much weight as possible. Another change that was requested was to remove part of the rear armor. The reason for this was the noted difficulty that arose during the replacement of the gun barrel and recoil cylinder due to lack of space. The opening to the rear provided the crew with plenty of room to effectively change the gun barrel. To avoid any possible delays, simple soft-steel doors were placed in the opening. On 17th September, further firing tests were conducted using Soviet but also German rounds adapted for the gun. These tests were to be followed up by driving trials.

While not directly related to these projects, the Germans were also experimenting with the idea of using half-track chassis as highly mobile anti-tank vehicles. One of these, which saw combat, was the Panzer-Selbstfahrlafette II, built using the experimental HKP 902 half-track. Only two would be built and they were lost in North Africa.

Another half-track project, the Panzer-Selbstfahrlafette II. Source: red

Name

This vehicle received the 7.62 cm F.K.(r) auf gp. Selbstfahrlafette Sd.Kfz. 6/3 designation. It is also known under the similar 7.62 cm F.K.(r) auf 5t Zkgw designation. There are some misconceptions about the ‘Diana’ nickname for this vehicle. According to T.L. Jentz and H.L. Doyle (Panzer Tracts No. Rommel’s Funnies), this name was associated with a subsequent Alkett project from 1942 based on the same half-track chassis, known as the 7.62cm PaK 36 auf 5t Zgkw Diana. While similar to the previous vehicle, it was to incorporate a number of improvements, namely a modified and improved anti-tank gun, better protection and fewer crew members. To complicate matters even more, according to the author T. Cockle (Armor of the Deutsches Afrikakorps), the ‘Diana’ nickname was actually given by the British.

Production Numbers

Only nine 7.62 cm F.K.(r) auf gp. Selbstfahrlafette Sd.Kfz. 6/3 vehicles were requested. For this reason, Buessing-NAG was tasked with the production of nine Sd.Kfz. 6 chassis, which were delivered during October and November 1941. The company responsible for their final assembly was Alkett. Interestingly, while the majority of sources agree that only nine such vehicles were built, author G. Rottman (German self-propelled guns) notes that only six vehicles were built.

Specifications

The Chassis

This vehicle was based on the modified chassis of the Sd.Kfz. 6 half-track. This half-track had a number of changes during its production run, aimed at improving its overall performance. In the case of the 7.62 cm F.K.(r) auf gp. Selbstfahrlafette Sd.Kfz. 6/3, the BN 9b subversion was used. Some of the changes compared to previous versions included redesigning the suspension by using the torsion bar units, adding two extra road wheels, and installing a stronger Maybach NL 54 TUKRM engine giving 115 hp @ 2,600 rpm. With this engine and a weight of around 10 to 10.5 tonnes (depending on the source), the 7.62 cm F.K.(r) auf gp. Selbstfahrlafette Sd.Kfz. 6/3 could reach a maximum speed of some 50 km/h. The fuel load of some 190 liters offered an operational range of 222 km on road and 112 km off-road.

The 7.62 cm F.K.(r) auf gp. Selbstfahrlafette Sd.Kfz. 6/3 used a torsion bar suspension with overlapping and interleaved double road wheels. While somewhat complicated, it provided a relatively good off-road drive. Source: https://www.nevingtonwarmuseum.com/sdkfz-63-diana.html

The Fighting Compartment

The Sd.Kfz. 6 cargo bay was replaced with a new fighting compartment that was protected by a simple but quite bulky box-shaped armored fighting compartment. The sides of this box-shaped fighting compartment were 3.6 m long and had a height of some 1.5 m. The rear plate was some 2 m wide with the same height. The front was open, with two smaller armored plates connected to the side walls. This is where the gun was to be located and its armored shield was to provide the crew protection from incoming fire. On top, this armored compartment was completely open, but could be covered with canvas to protect the crew from the harsh desert weather if needed. For this reason, three metal bar rails were added on the top to help stretch the canvas cover better.

The front was open in the center to provide room for the gun. Source: https://www.chaosbunker.de/en/2020/02/07/sdkfz-6-3-diana-for-the-afrikakorps-but-how/

On each side of this armored compartment, a large door was added for the crew to enter their positions. These doors could be opened toward the vehicle’s front. They were 90 cm wide and had a height of nearly 1 m. On the rear armor plate, a larger 60 cm wide door made of soft-steel was placed. This door was hinged at its bottom edge. Its primary function was to provide the crew with easy access in order to facilitate the replacement of the gun barrel and other parts. It could also be used to eject spent cartridges.

The doors are visible here. Source: https://www.armedconflicts.com/7-62-cm-FK-296-r-auf-gp-Selbstfahrlafette-Sd-Kfz-6-3-t8911

The Armor

The new fighting compartment was protected (except the rear positioned door, which was made of soft steel) by 4.5 mm armor plates. While it was hoped this would provide protection at least against small-caliber rounds, in reality, it did not. The front was mostly protected with a 3 mm thick gun shield. Some older sources mention that the overall armor thickness was either 8 or 10 mm thick. In a German war report about this vehicle’s performance, it was noted that this armor was insufficient to provide protection from even small caliber machine gun fire.

In theory, for any self-propelled vehicle that was lightly armored, the best defense was a well-selected combat position and good camouflage. While the first of these two could be achieved with good reconnaissance, the latter was quite tricky given the vehicle’s huge size. The half-track SPG was a notoriously large target, with a length of 6.33 m, a width of 2.26 m, and a height of 3.05 m.

While this vehicle was provided with 4.5 mm thick armored plates, in reality, these proved mostly useless against enemy return fire. The large size also did not help much in the survivability of this vehicle. Source: http://www.panzernet.net/panzernet/start.php

The Armament

The main armament was a captured Soviet 7.62 cm M1936 field gun. For installation in this vehicle, only the rear trail legs were shortened and then bolted down to provide stability during firing. The large wheels were also retained, but they were bolted down for the same reason. This gun had a traverse of 30° in both directions and an elevation of -7° to +20°. The armor penetration at 1 km was (depending on the ammunition used) 67 to 77 mm, more than enough to deal with enemy tanks encountered in North Africa.
In a German war report made by a Waffenamt liaison officer, it was noted that this gun (both in the towed and self-propelled versions) would generate fear among the enemy, who in turn would attempt to neutralize it by using artillery or airstrikes.

The 7.62 cm M1936 field gun, while possessing good anti-tank capabilities, was generally unsuited for this role. The main reason for this was the general arrangement of its traverse and elevation wheels. Namely, the traverse wheel was on the left, together with the gun sights, while the elevation handwheel was on the right side. As the gunner was positioned on the left, targeting was made quite difficult, if not almost impossible. The Germans took steps to address the issue, moving the elevation handwheel to the left side, but the linkages limited total elevation.

During the war, the Germans would modify and improve the 7.62 cm M1936 field gun for the anti-tank role. The changes involved adding a muzzle brake (but not all guns were equipped with it), cutting the gun shield in half (the upper part was welded to the lower part of the shield in a similar fashion to the PaK 40 two-part shield) and rechambering the gun to 7.5 cm caliber in order to use standard German ammunition ( as on the PaK 40). After these changes, the gun was renamed 7.62 cm PaK 36(r). This version was not the one mounted on the 7.62 cm F.K.(r) auf gp. Selbstfahrlafette Sd.Kfz. 6/3, but the original version of the gun.

The ammunition load was huge, with 100 rounds being stored in an ammunition bin which was located to the rear of the new fighting compartment. An additional 40 rounds could be stored on a towed trailer, if needed. Some sources claim that the ammunition load consisted of 64 rounds, while author D. Nešić (Naoružanje Drugog Svetsko Rata-Nemačka) mentions that only 20 rounds were carried inside.

The original Soviet gun had its traverse and elevation handwheel positioned on opposite sides of the gun, which made aiming this gun for anti-tank duties quite difficult. The Germans would later change this by moving both handwheels on the left side. Source: Wiki
The armor plates offered no real protection against enemy return fire, and possibly most vehicles were lost this way. To save time and to provide stability for the gun, the wheels of the gun were retained and can be seen here. In addition, the shortened trail legs are also visible. Source: https://www.nevingtonwarmuseum.com/sdkfz-63-diana.html
The 7.62 cm F.K.(r) auf gp. Selbstfahrlafette Sd.Kfz. 6/3 gun had a traverse of 30° in both directions and an elevation of -7° to +20°. Source: https://www.nevingtonwarmuseum.com/sdkfz-63-diana.htm

The secondary armament consisted of one 9 mm MP 40 submachine gun allocated to the vehicle commander. The remaining crew were issued with pistols for self-defense.

The Crew

This vehicle had a rather large crew, which consisted of a commander, a gunner, a driver, a loader, and two additional ammunition bearers. Beside the driver, who was fully exposed at the front, the remaining crewmen were located in the box-shaped fighting compartment. The number of crew members is listed as 5 in a number of sources.

The 7.62 cm F.K.(r) auf gp. Selbstfahrlafette Sd.Kfz. 6/3 had a large crew of six. The driver was probably in the worst situation, as he was completely unprotected and exposed to enemy fire. Source: https://guerra-mundial-1914-1945.fandom.com/es/wiki/7.62cm_Flak_36(r)_auf_Selbstfahrlafette_Zugkraftwagen_5t_Sd.Kfz._6/3_%22Diana%22

Forming the First Units and Organisation

At the end of September 1941, an order was issued to begin the necessary steps for forming a unit equipped with 9 such vehicles. The delivery of completed vehicles was expected to be ready by 25th October. In mid-November, a new order gave instructions to form three Platoons (Zuge). each equipped with three vehicles. The commanders of these Platoons were to be supplied with cars including and support staff, like a motorcycle messenger.

In North Africa

The 9 vehicles were transported from Germany to Italy at the end of December 1941. From there, they were transported by ship to Tripoli. Six vehicles arrived there on 12th January 1942, while the remaining three arrived in late February 1942. The first six 7.62 cm F.K.(r) auf gp. Selbstfahrlafette Sd.Kfz. 6/3 were used to reinforce the 3rd Kompanie (Company) of the 605th Panzerjäger Abteilung (Anti-tank Battalion), which was part of the 90th Leichte Division (Light Division). Beside the 7.62 cm F.K.(r) auf gp. Selbstfahrlafette Sd.Kfz. 6/3, the 605th Anti-Tank Battalion was also equipped with at least 6 Panzerjäger Is (anti-tank vehicles based on the Panzer I chassis).

Beside the small number of 7.62 cm F.K.(r) auf gp. Selbstfahrlafette Sd.Kfz. 6/3 vehicles, the 605th Anti-Tank Battalion was also equipped with the Panzerjäger I which can be seen in the background. Source: https://www.nevingtonwarmuseum.com/sdkfz-63-diana.html

As only six arrived in January, these initially saw action against the British in early 1942. By the 10th of February, probably due to high mechanical failures, only one vehicle of the original six was still operational. By March, with the arrival of the remaining three vehicles, the whole unit was finally attached to the 90th Light Division. The first losses occurred during April, when two vehicles were written-off, but the precise cause of these losses is not recorded.

In May 1942, the 605th anti-tank Battalion still had three operational platoons equipped with this vehicle, which were slightly reduced in strength. The 1st Platoon had three vehicles, while the remaining two Platoons each were equipped with two vehicles. These remaining seven vehicles saw extensive action during Unternehmen Venezia (Operation Venice), an Axis attack on the British positions at Gazala in late May 1942. On 28th May, the few 7.62 cm F.K.(r) auf gp. Selbstfahrlafette Sd.Kfz. 6/3 managed to beat back the tanks of the British 4th Armored Brigade near El Adem.

Due to further fighting, the number of these vehicles was reduced to four, while one was under repair on 8th June 1942. Due to further losses, by the start of July, only one operational and two non-operational vehicles were left. The same month, at least two vehicles participated in the Axis conquest of Tobruk. During the failed attempt to break the El Alamein line, one more was lost. At the start of December 1942, the last remaining 7.62 cm F.K.(r) auf gp. Selbstfahrlafette Sd.Kfz. 6/3 were finally lost. Of the 9 vehicles built, at least one was captured by the British in North Africa.

This vehicle was captured and examined by the British. Source: http://www.panzernet.net/panzernet/start.php
While the 7.62 cm F.K.(r) auf gp. Selbstfahrlafette Sd.Kfz. 6/3 offered a great increase in firepower and mobility, due to its weak armor and large size, it did not prove to be a successful overall design. Source: https://www.chaosbunker.de/en/2020/02/07/sdkfz-6-3-diana-for-the-afrikakorps-but-how/

Related Vehicles

7.62 cm PaK 36 auf 5t Zgkw ‘Diana’

The ‘Diana’ was a subsequent project from Alkett, meant to provide a more mature design for this type of vehicle. While based on the same chassis, it used the modified Pak 36(r), which had better anti-tank performance, better armor and a smaller crew.

The 7.62 cm PaK 36 auf 8t ZgKw ‘Artemis’

Using the Sd.Kfz. 6 was not the last attempt to develop an anti-tank vehicle based on a half-track chassis. The development of such a vehicle based on the larger Sd.Kfz. 7 was initiated in August 1941. It was to be lightly protected and to have a crew of only four. While a single prototype was completed, the whole project was eventually abandoned and no photos have survived.

Conclusion

The decision to build only nine 7.62 cm F.K.(r) auf gp. Selbstfahrlafette Sd.Kfz. 6/3 was quite justified, as this vehicle had a number of disadvantages. While its gun had good overall armor-piercing properties, its origin as a field gun made it somewhat unfit for the anti-tank role. The overall large shape of the vehicle offered an excellent target for enemy gunners. The weak, almost useless armor offered no real protection against any kind of enemy fire. The low numbers built also limited its overall performance on the front. In the end, while the Germans made some attempts to develop self-propelled anti-tank vehicles based on half-tracks, these projects ended in failure and were built in limited numbers.

The basic Sd.Kfz.6 half-track.
The 7.62 cm F.K. 36(r) auf gp. Selbstfahrlafette Sd.Kfz. 6/3 in action is North Africa. Both illustrations by David Bocquelet.

Specifications

Dimensions (l-w-h) 6.33 m,  2.26 m,  3.05 m
Total weight, battle-ready 10 to 10.5 tonnes
Crew 6 (Commander, Gunner, Driver, Loader and two Ammunition )
Propulsion Maybach NL 54 TUKRM 6 cyl., 115 hp @ 2,600 rpm
Speed (road/off-road) 50 km/h
Range (road/off-road) 222 km, 112 km (cross country)
Primary Armament 7.62 cm F.K.(r)
T Armor 3 to 3.4 mm

 

Sources

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