Rheinmetall 24cm Selbstfahrlafette (sFl) self-propelled gun

[EPOCH3]

Hi - while building models, I always like to look for reuse of a basic kit to create something new and different. A couple of years ago I bought several Trumpeter Gerät 040 Karl kits on sale to one day use for the basis for a couple of conceptual self-propelled gun projects (drawing board projects). I enjoy analyzing the development history of old heavy artillery pieces and combing that study with 3D modeling. The combination allows me create and visualize models of conceptual designs that designers would have been considering and playing with - some were refined to become production equipment while others were thrown in the trash.

One project will use the 35.5cm MRS L/27 M1 gun which I already modeled which will be attached to a production version of the 040 Karl hull/carriage and the other project is the 24cm Selbstfahrlafette (sFl). In the case of building the 24cm sFl I am planning to reuse the barrel, barrel carrier and breach assembly from my K3 3D printed model project (see elsewhere). Basically, the 24cm sFl took the 24cm K3 gun and added a muzzle brake and mounted it to a self propelled carriage (very much like the Gerät 040)

A first step was to figure out what needed to be modified on the Karl kit. Studying the concept drawing I have led me to conclude that the 24cm sFl equipment used one of the earlier gun mounts and carriage/Hull designs and not the final Gerät 040 production version. The trumpeter kit can be used but I'll need to remove one axle and shorten one end of the hull. The Sfl also requires a different gun mounting structure than what the standard K3 or even the Gerät 040 Karl used.

To start with I am attaching a few computer models I did showing what the 24cm Selbstfahrlafette (sFl) would have looked like (and what I plan to build). I figured out what the gun mount would have looked like so that is shown. I plan to 3D print this new part.

After I had completed the initial computer modeling and could see what the 24cm Selbstfahrlafette would have looked like, I wanted to know whether it could have reused the transport methods employed by the Gerät 040 Karl. Some of the pictures show that it could have been transported by rail in a similar way as the Gerät 040 Karl equipment. Because the 24cm sFl was several feet shorter, the mounting points that connect the carriage to the transport assemblies had to be moved (on one end). The barrel in transport mode would have also had to be slewed/moved towards the rear. One end of the transport structure also needed to be lengthened so I show an extension to what is provided in the Trumpeter kit.

I hope to have some pictures of the Karl kit once cut up and shorted in the next couple of weeks.

Happy modeling History....
Regards

[Bébert 1er]

Encore un projet de toute beauté. Bravo Greg.

[Milan Mynar]

Nice project, I looking forward for continuation.

[EPOCH3]

Hi - added picture showing how far back the barrel had to be retracted in order to transport.

[EPOCH3]

Hi - I forgot to mention that the drawing that was used as the reference for this model was originally part of the APG technical library during the 1940s. It was a 3-page fold out from a Rheinmetall handbook on artillery projects undertaken by Rheinmetall. The drawing is labeled "24cm (K4)". This is the only war time (or immediately after) graphical document I have ever seen that indicates what the K4 might have really looked like.
Regards

[EPOCH3]

Hi - I made these overnight for the K4 project - carriage mount and muzzle break in 1/35th scale

Regards

[EPOCH3]

Hi - I switched out the black resin used above in favor of a mixture of two types of other Formlabs resins. I am quite happy with the results. I am attaching a few pictures showing the build platform with the K4 parts as it was built just for reference. I made the elevation handwheel, trunnion end caps, barrel and muzzle break all at one time (in addition to some other parts for a crane I am building. I decided to integrate the muzzle break onto the barrel as a test and to also save time with assy. I redid the muzzle break separately as well just to be able to do an apples-to-apples comparison with the version I had previously done in the black resin.

Regards

[EPOCH3]

a few more pictures -

As shown, I simply snapped off the supports and did a dry fit to see how the two haves of the barrel would fit together - hardly a seam!

[EPOCH3]

Hi - just some more pics of preliminary dry fitting.
Had an extra breech and wiege assy left over
from my K3 project so here is what the K4 ordnance
would begin to look like.

Regards

[EPOCH3]

primer coat applied -