Pzkpfw VII vs. Pzkpfw VIII

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maltesefalcon
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Re: Pzkpfw VII vs. Pzkpfw VIII

Post by maltesefalcon » 10 Apr 2021 15:08

I hope I will be forgiven for resurrecting an old topic but I've done a little cyphering and pondering on the P1000 of late.

I'm now convinced the vehicle was at best a pipe dream. Extrapolating the fuel capacity, weight and range of a King Tiger, I'd estimate that 16 cubic metres of fuel needed to be on board to give the tank a useful range. Plus something like 40-50 personnel inside. Compare the magazine of a Gneisenau class battlecruiser for the space required for a useful number of powder and shells. All said and done there just does not seem to be enough interior space to incorporate the engines and all the above inside.

I did wonder one thing however. Through some miracle, if one ever got built I wonder what would happen if both guns were fired at the same time at 90 degrees to the longitudinal axis. It was already a bit top heavy. Would the recoil effect be enough to tip it over? :o

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Re: Pzkpfw VII vs. Pzkpfw VIII

Post by Carl Schwamberger » 20 Apr 2021 18:50

My first thought is each fills a larger portion of the CEP for artillery or aircraft bombs. Three of these would be useful target practice under real combat conditions.

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Re: Pzkpfw VII vs. Pzkpfw VIII

Post by maltesefalcon » 21 Apr 2021 00:18

Carl Schwamberger wrote:
20 Apr 2021 18:50
My first thought is each fills a larger portion of the CEP for artillery or aircraft bombs. Three of these would be useful target practice under real combat conditions.
Agreed. Anything of this type would be an absolute magnet for bombing.

To add to the pipedream detailed on Wikipedia, there was to be an infirmary and 2 BMW motorcycles on board. Why not just bring an ambulance along with you? And if you need 2 motorcycles, just bring them too. There would already be plenty of other vehicles, as there is no way this monster would travel alone. It would need infantry support and several half tracks or fully tracked vehicles to act as a supply auxiliary. At least one of those would need to have a jib crane to load shells and powder. (IRL the Schwerer Gustav had had something like an entire regiment dedicated to protecting and serving it.)

Again, an interesting concept, but it could never happen IMHO. I wish I had CAD/CAM skills to lay it out in 3D, to prove it once and for all.

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T. A. Gardner
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Re: Pzkpfw VII vs. Pzkpfw VIII

Post by T. A. Gardner » 21 Apr 2021 02:11

The Ratte / P1000 or whatever it's called, has a bigger problem than that. Just the sheer weight of something like it moving along average ground would end in it bogging down. The weight and vibration of the machine transmitted into the soil would collapse it. All one has to do to see the proof of that is look at NASA's shuttle mover.

Image

This machine has the weight and size to be something of a representative stand-in for the Ratte. It moves exclusively along a road of gravel ballast like a train does on a railroad. The weight and vibration of its movement would crumble asphalt or concrete, and certainly would destabilize soil causing it to liquify and fail.

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Re: Pzkpfw VII vs. Pzkpfw VIII

Post by maltesefalcon » 21 Apr 2021 03:33

T. A. Gardner wrote:
21 Apr 2021 02:11
The Ratte / P1000 or whatever it's called, has a bigger problem than that. Just the sheer weight of something like it moving along average ground would end in it bogging down. The weight and vibration of the machine transmitted into the soil would collapse it. All one has to do to see the proof of that is look at NASA's shuttle mover.

Image

This machine has the weight and size to be something of a representative stand-in for the Ratte. It moves exclusively along a road of gravel ballast like a train does on a railroad. The weight and vibration of its movement would crumble asphalt or concrete, and certainly would destabilize soil causing it to liquify and fail.
It's pretty cool, but the combined weight of a crawler and shuttle should be a lot more than 1000 tons. I don't always trust Wiki, but looks like rough numbers are 3000 tons for the crawler plus 1000 tons for the shuttle, with no hydrogen or oxygen in the tank. (I'm not a scientist so the tanks may have some pressurized inert gas when transporting to prevent collapse.)

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Re: Pzkpfw VII vs. Pzkpfw VIII

Post by Carl Schwamberger » 21 Apr 2021 05:40

maltesefalcon wrote:
21 Apr 2021 00:18
Carl Schwamberger wrote:
20 Apr 2021 18:50
My first thought is each fills a larger portion of the CEP for artillery or aircraft bombs. Three of these would be useful target practice under real combat conditions.
Agreed. Anything of this type would be an absolute magnet for bombing. ...
Actually I was thinking a sniping competition between crews of the US 240mm M1. Plinking the monster with 160kg projectiles fired at high angle, so the are coming back down on top at angles of +60 degrees.

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Re: Pzkpfw VII vs. Pzkpfw VIII

Post by maltesefalcon » 21 Apr 2021 13:26

Carl Schwamberger wrote:
21 Apr 2021 05:40
maltesefalcon wrote:
21 Apr 2021 00:18
Carl Schwamberger wrote:
20 Apr 2021 18:50
My first thought is each fills a larger portion of the CEP for artillery or aircraft bombs. Three of these would be useful target practice under real combat conditions.
Agreed. Anything of this type would be an absolute magnet for bombing. ...
Actually I was thinking a sniping competition between crews of the US 240mm M1. Plinking the monster with 160kg projectiles fired at high angle, so the are coming back down on top at angles of +60 degrees.
There was an SP version. Note the dramatic weight difference between this and P1000.

https://en.wikipedia.org/wiki/T92_Howit ... r_Carriage

Five were actually produced, but too late to see action. That would be an interesting duel for sure.

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Re: Pzkpfw VII vs. Pzkpfw VIII

Post by maltesefalcon » 21 Apr 2021 14:28

I had a look at the ground pressure issue mentioned above. There are 14,000 ton strip mining machines, on tracks that manage to cope with travelling on dirt without issues.

But to use a more contemporary example, Tiger II had a ground pressure of 10 psi on its battle tracks and managed to move about.
Using the theoretical numbers shown on Wiki, a rough calculation yields about 8 psi for the Ratte. That being said, I seem to recall another thread on this topic that commented that the width and length of the tracks would make it unsteerable. Not 100% sure about that one.

But that was only one of many issues. Again, I have no faith that this vehicle could ever be constructed as per the prevailing documentation shown online. One might call it a...sceptic tank. :D

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T. A. Gardner
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Re: Pzkpfw VII vs. Pzkpfw VIII

Post by T. A. Gardner » 21 Apr 2021 19:44

maltesefalcon wrote:
21 Apr 2021 03:33
It's pretty cool, but the combined weight of a crawler and shuttle should be a lot more than 1000 tons. I don't always trust Wiki, but looks like rough numbers are 3000 tons for the crawler plus 1000 tons for the shuttle, with no hydrogen or oxygen in the tank. (I'm not a scientist so the tanks may have some pressurized inert gas when transporting to prevent collapse.)
It represents the problem. You build something weighing 1000 tons (or more) and try to drive it across typical soil and you end up PDQ with it buried up to it's bottom in soil as the tracks liquify the ground beneath them.

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T. A. Gardner
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Re: Pzkpfw VII vs. Pzkpfw VIII

Post by T. A. Gardner » 21 Apr 2021 19:54

maltesefalcon wrote:
21 Apr 2021 14:28
I had a look at the ground pressure issue mentioned above. There are 14,000 ton strip mining machines, on tracks that manage to cope with travelling on dirt without issues.
These move very slowly and only infrequently. They are also generally moving on far more compacted soil than exists on the surface of most land.
But to use a more contemporary example, Tiger II had a ground pressure of 10 psi on its battle tracks and managed to move about.
Using the theoretical numbers shown on Wiki, a rough calculation yields about 8 psi for the Ratte. That being said, I seem to recall another thread on this topic that commented that the width and length of the tracks would make it unsteerable. Not 100% sure about that one.
And, the Tiger could be tough on roads and bridges, and had issues with soft ground. Unsteerable is the least of the problems with the Ratte. What is the rolling resistance of that track?

https://www.cat.com/en_US/articles/ci-a ... %20rows%20

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