Landships II

Steen Winther · Corporal

Dicke Bertha / Big Bertha 3d model

CharlieC · Legend

Have you read M. Romanych & M. Rupp's monograph "42cm "Big Bertha" and German Siege Artillery of WW1"?

Marc Romanych inhabits this forum from time to time and may be able to help with some of the details of the 42cm M-Gerät.

Your model would make a great first (and the most important) step in the production of a cardmodel of the M-Gerät.

I agree the Takom model just doesn't look quite right to me although I find it's hard to identify exactly where the Takom model is

in error.

Regards,

Charlie

MLW · Lieutenant-Colonel

To my knowledge, Arie Dijkhuis' drawings are the best available. He created plans for the two initial prototype guns sent to the field in August 1914 and the later production models built in 1915. There have been a few other people who embarked on projects to create detailed drawings, but as far as I know they never published anything.

Regards,
Marc

Steen Winther · Corporal

Hello Charlie,

Yes, I have read Marc's book - it gives a great overview of the whole weapons system with all the different variants.

To my eyes, the Takom model have a trail and a trunnion that are too sleek, and the trunnion is mounted too far forward and too low. And the blast shield is too vertical.

I have done a quick Photoshop mock-up of what I think is a more correct geometry:

Cheers,
Steen

Steen Winther · Corporal

Hello Marc,

Thanks for your post. I enjoyed your book about the Berthas a lot.

From an engineering perspective, I am really keen to know more about the firing procedure for big mortars in detail. I wonder if you know of any sources...?

The Paris model has a front platform (in front of the shield), which I didn't model. I wonder what this was for, and how widely it was used, because in all the many images have seen, it only appears in a couple?

Cheers,
Steen

CharlieC · Legend

Tackling the firing procedure from a different direction. The 42cm M-Gerät used cartridge cases (big ones) for

obturation. The case has a primer in the centre of the bottom - http://www.kaisersbunker.com/cc/cc16.htm.

By analogy with other Krupp guns it's likely that the primer was activated by a spring loaded firing pin.

The Krupp system was to cock and fire the gun/howitzer from a lever on the right side of the breech - this lever

had a ring for a lanyard. I think I've got some breech images of a 21cm Morser which possibly isn't too dissimilar

to the M-Gerät.

Regards,

Charlie

Later... first image is the back of the breech block in a 21cm Morser - the central firing pin assembly is obvious.

The second image is the right side of the breech. The opening lever is at the top with the firing lever immediately

below it. The M-Gerät seems to have had a crank handle on the top right side of the breech ring to open/close the breech.

-- Edited by CharlieC on Monday 5th of September 2016 11:50:14 AM

-- Edited by CharlieC on Monday 5th of September 2016 01:34:11 PM

Roger Todd · Legend

Steen's renders look excellent! Far better proportions than the Takom model. For some time I was trying to create my own plans of the Bertha, and had been in correspondence with Arie a few years ago (he very kindly sent me early drafts of his work on the Bertha). I missed the plans he uploaded here last year, but attached is basically as far as I got.

Steen Winther · Corporal

An update showing the current state of the Solidworks 3d model with new renders. I am looking for info on the brackets used to guide/attach the ammunition tray to the breech. Several pics shows a flat-ish, detachable bracket mounted on the breech, but the Aberdeen Bertha had what looks to be guide wheels mounted in a horizontal plane. How did these engage the ammunition tray? Can anyone shed light on these devices....? confuse

Roger Todd · Legend

Superb progress, Steen! I wonder if those horizontal wheels are nothing to do with the ammunition tray but were, rather, to help guide the barrel into the cradle during assembly? Just a thought.

Steen Winther · Corporal

Thanks Roger

Interesting thought that the guide-wheels could be for some other purpose; although they do seem slightly underwhelming for guidance of a 13 t barrel. Again, this is a detail that I have only seen pictures of on the Aberdeen Bertha, all other guns, that I know of, have a flat-ish, T-shaped bracket....?

Haverba · Sergeant

Beautiful impressive work and very welcome. Although I have already built the TAKOM kit and were able to adjust a few details, based on your excellent drawings I will make a new model.

Big Bertha was a "secret" weapon and just a few usable photo's exists. As with many photo's taken the perspective is almost everytime from a standing uprigth position. Sometimes photo's published are copies from copies loosing details. Printing quality can be poor as well.....

Success,

Harry

Steen Winther · Corporal

Thanks for your comments Harry

I also bought the Takom kit with the intention of redesigning the parts that needs improvement using CAD, but there are so many details that are dodgy, that it is very hard to decide what to keep and what to redesign, so the project hasn't taken off yet....!

Roger Todd · Legend

Steen Winther wrote:
Thanks Roger
Interesting thought that the guide-wheels could be for some other purpose; although they do seem slightly underwhelming for guidance of a 13 t barrel. Again, this is a detail that I have only seen pictures of on the Aberdeen Bertha, all other guns, that I know of, have a flat-ish, T-shaped bracket....?

You're right, looking more carefully (rather than making a knee-jerk reply without looking!) at the large Aberdeen photo, I see the horizontal wheels are actually attached to the rear face of the breech-ring, not to the cradle and thus cannot have the purpose I speculated upon. Perhaps, though, they were to loop cables around as part of a sort of windlass-type setup for pulling the barrel into the cradle during assembly?

Steen Winther · Corporal

Just a little update showing my findings regarding the accuracy (or lack of same) of the Takom Big Bertha model. The attached drawing shows just how much too long both the trail and the barrel are, making the overall size much too large. I am presently reverse engineering the Takom kit in CAD with the intention of revising the most glaring mistakes in order to produce a more accurate model.

Roger Todd · Legend

Fantastic progress, Steen! I must say that after my initial enthusiasm at the release of the Takom model a couple of years ago or whenever it was, I've become very disillusioned by it. There are so many errors, not least of which being that it's basically over-sized quite apart from proportional errors, detail errors etc., that it's impossible to modify it to make it accurate, you may as well build one from scratch.

After doing a comparison using Photoshop, I'm pleased to see that my old scale drawings (well, early stages anyway, I never finished them) are very close to yours in overall proportions...

Seeing as you're working up your drawings in a CAD programme, are you considering using it as a basis to get all the parts 3D-printed as a kit?

Haverba · Sergeant

Beautiful work Steen. Impressive.

"Hope you will be able to do a Gamma gun as well. wink "

Success,

Harry

Steen Winther · Corporal

Just wanted to share access to my 3d model on GrabCAD for those who would like to take a closer look:
grabcad.com/library/dicke-berta-1
When you open the model in the 3d viewer, you can spin it around, make cut views, measure dimensions, etc.
Cheers,
Steen

CharlieC · Legend

Thank you very much for releasing your 3D model.

The viewing tool on Grabcad is quite outstanding.

Regards,

Charlie

Roger Todd · Legend

Wow, amazing, thank you Steen!

28juni14 · Hero

Hallo Steen!

Can you tell me the software you are using? Rhino?

MFG

Jacke

Steen Winther · Corporal

Yes, I am using SolidWorks 2014

Cheers,
Steen

sneakyimp · Private

Steen, This model looks GREAT! I downloaded the STL files from Hans van Oerle and these are importing nicely into blender.

Ruhrpottpreusse · Lieutenant

Hello!
A very good work! Congrats!!!!
Here are a few photos from my collection

CharlieC · Legend

Not all the images are of Dicke Bertha - there are 3 of Emil Cherubin's wooden model of the Dicke Bertha which toured Germany in the 1930s. - thanks to Roger Todd who wrote the appendix to the main article in Landships II [http://landships.info/landships/artillery_articles.html?load=/landships/artillery_articles/42cm_M_Gerat.html]

Charlie

-- Edited by CharlieC on Thursday 14th of October 2021 11:11:58 PM

Ruhrpottpreusse · Lieutenant

Yes, you´re right. But the models are similar to the originals.