The Modelling News: Preview: MiniArt's 1/35th scale 7.5cm Pak 40/4. Selbstfahrlafette RSO

MiniArt has shown the first CAD images of their 1/35th scale 7.5cm Pak 40/4. Selbstfahrlafette RSO along with art & info on this new kit. See the inside out of this coming kit in our preview...

Preview: MiniArt's 1/35th scale 7.5cm Pak 40/4. Selbstfahrlafette RSO

7.5cm Pak 40/4. Selbstfahrlafette RSO

From MiniArt Models

1/35th scale

Kit No. 35483

Decals for four options in the box.

The kit includes clear parts & photo-etch metal

Product Link on the MiniArt Website

The subject: 7.5cm Pak 40/4. Selbstfahrlafette RSO
The acronym RSO stands for “Raupenschlepper Ost,” which translates as “Caterpillar Tractor East.". The terrible muddy and icy conditions experienced on the Eastern Front convinced Germany of the need for a highly mobile, tracked vehicle. Steyr proposed the RSO, and it immediately became a popular vehicle thanks to its mobility and reliability. In all, about 23,000 RSO vehicles were produced by a range of manufacturers. The original version had a pressed-steel cab and a typical truck-style cargo bed at the rear. It was powered by a Steyr 85-hp V8 engine that offered a top speed of 30 km/h.

An early 7.5 cm PaK 40 auf RSO. The front wedged-shaped section housing the driver and engine.

Initially designed as a prime mover and artillery supply vehicle, the RSO eventually adapted to a wide range of roles. The RSO underwent several design iterations, starting with the RSO/01, which featured a pressed-steel cab with a truck-like configuration. Subsequent models, RSO/02 and RSO/03, adopted a simpler, soft-top, slab-sided metal cab. All versions boasted wooden, drop-side cargo beds typical of light trucks from that era. Initially powered by a Steyr 3.5L V8 petrol engine, the RSO/03 was later upgraded to a Deutz air-cooled diesel engine. Approximately 23,000 RSO units of all versions were produced.

The 7.5cm Pak 40/4. Selbstfahrlafette RSO was based on the Raupenschlepper Ost chassis, a cargo vehicle better known as the RSO. This little vehicle was not much larger than a small truck but was modified to carry a disproportionately large gun. Once fitted, the PaK 40 auf RSO was capable of killing most tanks on the battlefield, despite weighing only 6 tons.

The completely open top and sides left the crew extremely vulnerable, making it an unpopular vehicle.

The 7.5 cm PaK 40 auf RSO comes from the same line of thinking that resulted in the German Panzerjäger vehicles, such as the Marders and Nashorn. These vehicles were a solution to the practical issue of anti-tank weapons being pulled around by half-tracks and wheeled vehicles, requiring them to be set up by the crew in a vulnerable position. To address this issue, the Germans began looking into mounting the anti-tank gun on a tracked chassis, allowing the vehicle to move through rough terrain and fire almost instantly. In 1943, plans were made to mount the 7.5 cm PaK 40 anti-tank gun on the chassis of a small cargo vehicle known as the RSO. The running gear and engine remained the same as on the RSO, with four simple road wheels per side and an 85 hp engine in the front.

A top view from the rear of the PaK 40 auf RSO showing its gun platform. As seen here, the sideboard has been dropped to increase the platform’s size. Note the panels in the floor that covered the ammunition.

However, the PaK 40 auf RSO had an entirely new front end that left the driver completely exposed, with a wedge-shaped and armored cab to a maximum of 10 mm. The platform floor served as ammunition storage for the PaK 40, with the rounds accessed by lifting panels. The crew were only protected by the standard PaK 40 gun shield, which consisted of a 4 mm thick plate, a 25 mm air gap, and then another 4 mm plate. This left them extremely vulnerable to enemy fire, even more so than on a towed PaK 40 because it was higher up.

A rear view of the PaK 40 auf RSO. You can see the pedestal mount that the gun is attached to.

One of the major drawbacks of the vehicle was its top speed, which was significantly impacted by the added weight of the PaK 40. As a result, it had a top road speed of just 11 mph, which made it less useful as a mobile tank destroyer. Despite its promising concept, the PaK 40 auf RSO was ultimately canceled in June 1944 due to its low speed, loud engines, and reliability troubles, as well as the vulnerability of the crew. Still, around 60 were built and issued to units on the front lines, where they were mostly given to armored divisions in an attempt to replace their heavily depleted forces.

You can see just how top-heavy this machine is and how little it protected its crew in the photo...

The kit: MiniArt's 1/35th scale 7.5cm Pak 40/4. Selbstfahrlafette RSO
MiniArt's 7.5cm Pak 40/4. Selbstfahrlafette RSO kit features all the parts to make one RSO early type right out of the box. Four marking choices are included.

You can see some of the chassis and rear running gear of the RSO in this image.
And again, with even less on, the cab and tray are of here showing the full track and suspension and access to the engine.

The full Steyr 3.5L V8 petrol engine that powered the early variants is here with a drive train leading to the drive wheels. A little wiring harness is all one would need.