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Ground Pressure


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LOL - now you're blowing your bandwidth limit ;)
I noticed that. Arggh! Oh well, it seems to be working again.

Second paper is up now as well, this one has more tank vs tank stuff.

To rephrase, both reports by Rowland on armored vehicle ground pressure are posted here. Click on the other interests link down and to the left on this Africa page to get to them.

Cheers

[ November 13, 2002, 01:38 AM: Message edited by: Paul Jungnitsch ]

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A little more info for those interested in this ground pressure thing, a couple of interesting responses from posting on the AFV news forum:

I had written:

"Wondering what other people think of the articles as well. For example the Elephant having only 20% heavier ground pressure than a King Tiger when measured normally but over double the ground pressure using his method seems to make a lot of sense according to combat accounts I've read (although both are equally difficult to retrieve if they DO get bogged). If true though it would mean that regular ground pressure ratings are next to useless. Could this be the case?"

Responses:

Depends. NGP (Nominal Ground Pressure) is probably fine as long as you are interested in the performance on a hard surface. For off-road performance, I would think MMP is much more indicative of true performance.

MMP also does an excellent job of explaining why the Churchill should perform better than a Sherman on soft ground and why the Panther, and to a lesser degree the Tiger, did so well in the dirt. NGP is not very usefull for highlighting these differences.

Btw, MMP is described in detail in Ogorkiewicz: "Tank Technology" that came out ca. 1991, but I've found it difficult to find the necessary data for doing the calculations. The papers you linked to certainly has the benefit of presenting the data for a wide variety of WWII vehicles!

(Claus B)

Theory of Ground Vehicles_ by J. Y. Wong (John Wiley & Sons) 1978 covers the same ground, so to speak. ISBN 0-471-03470-3, plus a lot more about road vehicles. Heavy math engineering approach, with lots of diagrams to help us visualize things. It's funny that most book about tanks (except Ogorciewicz) don't mention this concept. Nominal groud pressure (length times width divided by weight) is a limited measure. There are many more factors affecting trafficability. Dynamic loading of the track system for instance, occurs during motion over land, such that the front wheels on the ground carry a greater load than the rear wheels. The Russians measured this on BT tanks. Another recommended title is _Theory of Land Locomotion_ by Bekker. I think this was published in the 1950's.

(Robert Livingston)

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Great information. I hope BTS finds time to read this info.

"M3 Halftrack 363"

I'm sure many here are familiar with the Battle of Singling, in which Colonel Creighton (sp?) Abrams send a company of armored infantry and a Sherman company to take the town of Singling France. The ground in front of the town was muddy, forcing the infantry to abandon their half tracks and ride the tanks in a dash for the town behind a 105mm battery smokescreen. In CM you can't simulate this, halftracks actually float over the mud better than sherms. The numbers presented by Paul seem to more accurately reflect the reality in this case than do the current gp ratings. This applies to CMBO, not sure if it's different in CMBB.

This brings up another question, why not simply use ground pressure ratings for all vehicles rather than having a seperate poor/avg/good rating system for wheeled vehicles.

I'd be curious to know the MMV ratings for the M1, though that was after the time of the reports cited by Paul. I drove one for several years and it had a tendency to 'float' or hydroplane over soft or muddy surfaces, especially wet sod such as that in germany after rain, so badly that you sometimes had trouble going up a gentle slope or along the side of a slope without sliding back down.

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Originally posted by JonS:

Quick question: 'track pitch', as used by Rowlands, refers to the length of the individual track segments, is that correct?

Cheers

Jon

I was wondering about that too. 'Pitch' in terms of roller chain is the distance from one pin to the next, I assume that carries over to tracks in the same way.

tracks.gif

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  • 1 month later...
Originally posted by Paul Jungnitsch:

Here we go....

Was doing this out of interest, thought I may as well post it. A more complete list, in order of best to worst of ability to traverse soft ground.

Panther 150-155

M-24 Chaffee 175

BT-5 175

T-34/76 174-186

Churchill M IV 177 (11 roadwheel)

Tiger II 184

Tiger I 185-192

Churchill VII 182-223

Churchill Mk IV 217 (9 roadwheel)

Panzer IV 184-191

T-34/85 196

Sherman HVSS 205

M3 Stuart 216

Panzer III 220-232

BT-7 240

JS-II 245

Universal Carrier 253

Sherman VVSS 282

E-100 290

Cromwell VII 300

Cromwell IV 352

M3 Halftrack 363

US 2 1/2 ton 367 (6X6)

Elephant 370

SD KFZ 231 (8 rad) 415

M8 Greyhound 460

Maus 470

Opel Blitz 525 (4X4)

Opel Blitz 700 (4X2)

For comparison

M29c Weasel 27

Caterpillar D7 32.5 (widepad)

Caterpillar D7 80 (regular)

Leopard II 201

M-60 221-236

T-62 242

M-47 246

AMX-30 249

THIS its GREAT

Great Work!

I hope this info can find its way into the engine re-write for BOGGING purposes!

smile.gif

-tom w

[ January 13, 2003, 11:36 AM: Message edited by: aka_tom_w ]

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Originally posted by BBToys:

Is there a list of which German vehicles get fitted with the Ostketten (track extensions to increase surface in contact withground) and should CMBB vehicle data include possible alternative purchases for those so outfitted?

Thanks, Richard

Oh my god!

How could there be such an omission!

Boris

london

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Originally posted by BBToys:

Is there a list of which German vehicles get fitted with the Ostketten (track extensions to increase surface in contact withground) and should CMBB vehicle data include possible alternative purchases for those so outfitted?

Thanks, Richard

I think for the Germans these special tracks were pretty normal tracks, just wider.

The extension of extisting tracks with appendixes to the sides has been done by the Americans to the Sherman tanks. I wonder whether the Russians received these extensiond or maybe built some of their own.

Both solutions are probably of little value, especially the American one. The suspension and the wheel configuration do matter.

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Originally posted by mididoctors:

</font><blockquote>quote:</font><hr />Originally posted by BBToys:

Is there a list of which German vehicles get fitted with the Ostketten (track extensions to increase surface in contact withground) and should CMBB vehicle data include possible alternative purchases for those so outfitted?

Thanks, Richard

Oh my god!

How could there be such an omission!

Boris

london</font>

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BBToy,

Is there a list of which German vehicles get fitted with the Ostketten (track extensions to increase surface in contact withground)...
Interestingly enough, I have seen hardly any photographic evidence that these were used in the East. At least, not in any great numbers. The only picture I have ever seen off the top of my head is of a scale model of a StuG III smile.gif In other words, out of the thousands of pictures I have seen of German tanks in the East and West, to the best of my memory I have never seen one with the track extenders.

They appear to have been used only sparingly in the West on US based vehicles. Most shots I have seen of them, there are quite a few missing or bent. The extensions were not of the same strength and durability as the main track. Therefore, they could bend or break off without (apparently) too much trouble.

...and should CMBB vehicle data include possible alternative purchases for those so outfitted?
Nope smile.gif Making purchase options for exceptional devices, upgrades, conditions, etc. is simply not possible in CMBO or CMBB. This will be rectified in the new engine.

Steve

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