Tank Off Road Performance Tests and Possible Wackiness

[altipueri]

Well it's even stevens so far. Drink a bit more of that Kalmogorov-Smirnov and let's have both back in the ring for the next round.

[sburke]

Well it's even stevens so far. Drink a bit more of that Kalmogorov-Smirnov and let's have both back in the ring for the next round.

well in fairness to Vanir, all the above quotes reference the mechanical reliability factor which he explicitly rules out for testing as it is not modelled. Vanir is not arguing that the Panther was a more mechanically reliable vehicle, he is arguing that it should (mechanical factors aside) in CM cross a muddy field with less chance of bogging than a Sherman.

As much as I wish the engine modelled mechanical issues or included it somehow, so far I'd have to agree with Vanir. If that aspect were included, I think Vanir would agree that it would change the balance of that equation.

The maneuverability items cited do not sound like bogging issues so much as issues caused by the length of barrel and width both of which are also not a factor in CM..unfortunately.

I score this round as going to Vanir - any other judges?

[Baneman]

While your sources are impeccable, Sgt Joch, they are, however, irrelevant. Since mechanical reliability is not modelled in CMBN, it has no bearing on the in-game off-road performance of any tanks.

Much like combat flight-sims where you get a perfect factory version of a plane each time you start ( with its inevitable and unavoidable slight advantage to whatever side had in reality poor maintenance and/or mechanical design ), so too here the tanks are the ideal.

So the off-road performance of any tank in-game can only really be looked at in terms of their ground pressure, weight etc.

And this is where things appear to be slightly off.

( unless of course, I'm completely wrong and some sort of mechanical "stuff" is calculated under the hood, but we need BFC to tell us that then )

Edit: ninja'd by sburke while typing

[Sgt Joch]

While your sources are impeccable, Sgt Joch, they are, however, irrelevant. Since mechanical reliability is not modelled in CMBN, it has no bearing on the in-game off-road performance of any tanks.

Agreed and I said as much in post#47 and #58, but Vanir is now arguing that the Panthers, Tigers, et. al, did not break down more often off road than the Shermans. That is what we are on about now.

Keep track of what the game is if you are going to score, boys.

[sburke]

Keep track of what the game is if you are going to score, boys.

Why? It isn't like I actually know how to count. pffft elitists!

[Baneman]

... but Vanir is now arguing that the Panthers, Tigers, et. al, did not break down more often off road than the Shermans. That is what we are on about now.

I'm not seeing that in post #71, 72, 73 or 74.

And hopefully, that is not what we are on about now, since that is a digression from the OP which still seems worthy of examination ( the OP, not the digression ).

[Vanir Ausf B]

Its very easy to cherry pick quotes from secondary sources, but let's see what the people who actually operated Panthers thought.

I only cherry pick quotes for relevance. As for secondary vs. primary, you don't need primary source material to know the US Army went to great effort to rectify a deficiency in Sherman soft ground performance. But if you want primary source material there is plenty of it out there.

_____

"Wherever we have seen Tiger and Panther tanks they have not demonstrated any inferior maneuverability. Near Puffendorf, Germany, several Tiger Royal tanks were encountered. These Tiger Royals were able to negotiate very soft ground and their tracks did not sink as deeply into the soft ground as did our own."

-- Capt Charles B. Kelley, Company D 66th Armored Regiment

The wider tracks on the Mark V and the Mark VI enables it to move much better cross-country and in muddy or snow-covered terrain than do the narrow tracks of the Sherman tank. The field expedient of duck bills added to widen the Sherman tread aids but does not affect the advantage the Mark V and Mark VI tanks have. It is my opinion that the Mark V and Mark VI enemy tank is far superior in maneuverability to our own Sherman tanks.

-- Captain Henry Johnson, U.S. Army Report on United States vs German Armor, March 1945.

Operating across typical ground the Mark V left a track imprint one-half inch deep. It did not break through the ground surface. Similar results were obtained with the M4A3E8. Other tanks of the M4 series with narrow track and no track extensions broke through the ground surface, leaving a track imprint two inches deep.

-- United States Vs. German Equipment: As Prepared for the Supreme Commander

_____

Of course the problem is, once again, that you are refusing to evaluate CM's off-road rating for what it is while insisting on evaluating it based on what you wish it were, all the while ignoring that it would be wrong either way.

A few comments on your examples, although I'm probably going to regret indulging your off-topic excursions.

This is what Fritz Bayerlein, commander of Panzer Lehr thought of his Panthers:

Quote:

While the PzKpfw IV could still be used to advantage, the PzKpfw V [Panther] proved ill adapted to the terrain. The Sherman because of its maneuverability and height was good ... [the Panther was] poorly suited for hedgerow terrain because of its width. Long gun barrel and width of tank reduce maneuverability in village and forest fighting. It is very front-heavy and therefore quickly wears out the front final drives, made of low-grade steel. High silhouette. Very sensitive power-train requiring well-trained drivers.

It is true that the Pz IV was the most effective German tank in the Normandy hedgerow fighting and it pains me that CM doesn't reflect this. The guns on the StuGs were too low and the Panther was too wide-bodied to fit down narrow country lanes between hedgerows, and its long gun interfered with turret traverse in towns and forests. While it's a pity this is not a factor in CM it has nothing to do with off-road performance. Most of these situations would have occurred on-road.

The requirement for well-trained drivers is an interesting subject on its own. That the Panther was rushed into service before it was ready and was hilariously unreliable at Kursk is well documented. But the Germans were constantly modifying. By October '44 there was very little on that tank's drive train unchanged, and the steadily improving readiness rates reflect that. There is strong evidence that while late-model Panthers were highly temperamental and unforgiving of poor treatment, a good crew could coax a lot out of them. There are documented cases of Panthers logging over 1000 km without a breakdown.

Here is one U.S. Army report on Panther maneuverability:

_____

Except for the ability of the tank to make a pivot turn about its own axis, its steering system does not contribute to satisfactory maneuverability and this tank (Panther), even though it has a higher top speed than a medium tank M4A1, could not keep up with the medium tank on a course where the curves were frequent. It is readily realized that practice in operating these vehicles (Panthers) would contribute greatly to driver skill and , therefore, increased mobility; but it should be pointed out that in any event it is necessary for the Panther driver to gauge any approaching turn and select the proper transmission ratio to negotiate that turn.

-- U.S. Army report, January 12, 1945

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And here a similar report:

_____

It has been claimed that our tank (Sherman) is the most maneuverable. In recent tests we put a captured German Mark V against all models of our own. The German tank was the faster, both across country and on the highway and it could make sharper turns. It was also the better hill climber.

-- U.S. Army Report on United States vs German Armor, March 1945

_____

Same tank, different drivers, different outcomes.

A captured Panther crew member had these comments about the perceived mechanical shortcomings in a September 1944 British report:

_____

PW (prisoner of war) denied the statement that the Panther, from the point of view of engine, was a poor tank. He said that like all tanks it had teething problems but once these had been overcome it was much superior to the Pz.Kpfw IV. The following are a few of the defects and their improvements:

1) The steering clutch had given trouble but this was due to the inexperience of the drivers.

2) The inability on the part of the (British test) driver to engage third gear had been due to his lack of experience in synchronizing engine speed with gear box speed. There was no difficulty once the driver had gotten used to the tank.

3) The final drive had given trouble but now had been improved.

4) The faults in the pressure lubrication system had been due partly to the oil pump. This had been improved and an eight main bearing had been fitted.

The 231 (23.1) liter HL 230 was the most powerful tank engine that PW knew about. He agreed that it was too weak for the Tiger II (Tiger . He stated that it was originally built too compact and that it got too hot, hence the trouble with the cylinder head gasket. An experienced driver was essential. It has now been greatly improved. The centrifugal governor on the carburetor was an excellent idea.

_____

A major problem for the late-war German panzers was that due to fuel shortages new drivers were only getting a few hours of practice during training, and they would just thrash the transmission.

But it appears that experience has told the French never to USE this capability. It is an advantage to be able to pivot a tank in combat. But not if the result is an immobilized tank.

They were told not to do it and they probably rarely did. But in the heat of battle sometimes it was too useful a capability to ignore.

_____

"I saw a Mark V tank turn in place and move off in a new direction without having to use the back up and move forward system that our tankers are compelled to use."

-- U.S. Army report on United States vs German Armor, March 1945

(hey looky there, another primary source )

[Vanir Ausf B]

Agreed and I said as much in post#47 and #58, but Vanir is now arguing that the Panthers, Tigers, et. al, did not break down more often off road than the Shermans.

Um, no, I did not say that. I specifically said the exact opposite. What I did say is that while all tanks are more vulnerable to breakdown off-road there is no reason to assume the "Big Cats" were exponentially worse off-road than they were on. Look at the expected longevity of the Panther's final drive. 150 km, not 150 km on-road 50 meters off-road. The reason it was German SOP to transport tanks by rail rather than road if the distance was greater than 100 km isn't because of their off-road performance, it was because of their on-road performance. The primary factor was distance driven.

There was a lot of variation between vehicles types. Even though the Jagdpanther was built on the Panther chassis it used a different final drive that was more durable. Tigers and KTs were well known for their adverse relationship with hills. There are many stories of Tigers in Italy catching fire while climbing long mountain roads. There was a KT in the Ardennes that, um, blew a tranny while climbing a hill and rolled back down into a house. But these were on paved roads. The key factor was the hill, not on-road vs off-road.

[Vanir Ausf B]

I'm not seeing that in post #71, 72, 73 or 74.

And hopefully, that is not what we are on about now, since that is a digression from the OP which still seems worthy of examination ( the OP, not the digression ).

Precisely, thank you. While off-road ability and mechanical reliability both affect mobility in the broadest sense of the term they do so in different ways via different means and are manifestly not the same thing at all. Lumping them together confuses the issue, and the fact that the game doesn't even consider one of them relevant makes it all the more of an obfuscation.

I have no issue with the idea of CM modeling mechanical reliability in some way, but the subject needs to be considered on its own merits. And if we are to start introducing that type of operational mobility factor then logically I see no reason why fuel supply and consumption rates should not also be brought in. Big Cats were prodigious fuel guzzlers and a lot of them were abandoned when the fuel gauge hit E.

[Vanir Ausf B]

Back on-topic (hopefully ).

I ran across this section in the CMBN manual

GROUND CONDITIONS, BOGGING AND IMMOBILIZATION

When issuing Movement commands, keep in mind the ground condition that

you want to order a unit to move over. All vehicles are rated for Offroad

performance and ordering a non-tracked personnel carrier to FAST move

across a muddy field is very likely to bog it down. Slower speeds decrease the

chance of a bog to some extent.

My last test results suggest this section is either incorrect about the difference speed makes or the difference is too small to be significant.

[Sgt Joch]

Well again, you are as you so eloquently put it, "beating a strawman", no one here is arguing that under ideal conditions a Panther was not theoretically more maneuverable than a Sherman, our point is that those ideal conditions did not exist. Panthers, Tigers, Tigers II all had weak drivetrains, the Germans knew it and because of that, they were careful in using them offroad except under "ideal" conditions. At Anzio, the entire Panther Battalion was kept in reserve because the ground conditions were "muddy".

Now back to CM. The game does not model mechanical reliability so the German player does not have to worry about it, because of that, the offroad capability of Panthers, Tigers, Tigers II is already better than real life. Just because the game does not model reliability does not mean you should just ignore it and model the German tanks as if they were perfect and give them even better offroad capability than they already have. Now if there are any obvious bugs we will look at it, but I would not expect any major changes, unless BFC decides to model mechanical reliability.

Now if you are still seriously arguing that the Panthers, Tigers and Tigers II were as mechanically reliable off road as the Sherman, I have yet to see any proof.

[Sgt Joch]

Um, no, I did not say that. I specifically said the exact opposite. What I did say is that while all tanks are more vulnerable to breakdown off-road there is no reason to assume the "Big Cats" were exponentially worse off-road than they were on. Look at the expected longevity of the Panther's final drive. 150 km, not 150 km on-road 50 meters off-road. The reason it was German SOP to transport tanks by rail rather than road if the distance was greater than 100 km isn't because of their off-road performance, it was because of their on-road performance. The primary factor was distance driven.

There was a lot of variation between vehicles types. Even though the Jagdpanther was built on the Panther chassis it used a different final drive that was more durable. Tigers and KTs were well known for their adverse relationship with hills. There are many stories of Tigers in Italy catching fire while climbing long mountain roads. There was a KT in the Ardennes that, um, blew a tranny while climbing a hill and rolled back down into a house. But these were on paved roads. The key factor was the hill, not on-road vs off-road

expected fatigue life of 150 km means it is a fragile piece of equipment which could break if too much strain is put on it, i.e. moving uphill, downhill, turning. Moving offroad on uneven, muddy, soft sand just increases the strain and chances of a breakdown.

To put the 150 km in perspective, the drivetrain of a new quality car is designed to last at least 100,000 km.

[Vanir Ausf B]

This is just getting silly. Actually, it was silly before. Now its ridiculous.

Well again, you are as you so eloquently put it, "beating a strawman", no one here is arguing that under ideal conditions a Panther was not theoretically more maneuverable than a Sherman, our point is that those ideal conditions did not exist.

I'm almost at a loss for words here.

I have detailed the Panther's various physical characteristics that gave it such excellent off-road performance. But when you get right down to it, the main factor was that it had very wide tracks relative to its weight.

When you say it was only more maneuverable than a Sherman under "ideal conditions" (whatever those are) you are essentially claiming that those wide tracks only functioned properly under ideal conditions.

Bizarre. :confused:

Panthers, Tigers, Tigers II all had weak drivetrains, the Germans knew it and because of that, they were careful in using them offroad except under "ideal" conditions.

No they were not. You made up that claim out of thin air. I've already posted first person accounts of them operating in muddy conditions. If what you said was true they would have been essentially road-bound for half the year. Crazy talk.

At Anzio, the entire Panther Battalion was kept in reserve because the ground conditions were "muddy".

The extremely muddy conditions relegated armour attacks to the few roads available. This forced any gains to be made to infantry attacks, which resulted in bloody battles and heavy casualties on both sides.

http://www.flamesofwar.com/Default.aspx?tabid=112&art_id=2211

_____

Congratulations. You have succeeded in proving the Panther had limits. But that has never been in question. The question is how it compared to other tanks.

Now back to CM. The game does not model mechanical reliability so the German player does not have to worry about it, because of that, the offroad capability of Panthers, Tigers, Tigers II is already better than real life.

Aaand here we go again with the predictable conflation of off-road ability and mechanical reliability. This is getting tedious so I'm just going to cut and paste what I previously wrote so you can not understand it all over again.

While off-road ability and mechanical reliability both affect mobility in the broadest sense of the term they do so in different ways via different means and are manifestly not the same thing at all. Lumping them together confuses the issue, and the fact that the game doesn't even consider one of them relevant makes it all the more of an obfuscation.

Just because the game does not model reliability does not mean you should just ignore it and model the German tanks as if they were perfect and give them even better offroad capability than they already have.

Right. That is what I want, to make German tanks perfect.

It is becoming more apparent with each post that you have no intention of debating this issue honestly and are just trying to derail the discussion under a torrent of idiocy.

Now if there are any obvious bugs we will look at it, but I would not expect any major changes, unless BFC decides to model mechanical reliability.

If there are no major changes it will most likely be because Charles doesn't read this forum and Steve is probably oblivious to the issue. I can't imaging it being because they actually believe the crap you're peddling.

Now if you are still seriously arguing that the Panthers, Tigers and Tigers II were as mechanically reliable off road as the Sherman, I have yet to see any proof.

Still arguing? When did I say that? Oh, wait I didn't. What I actually said was:

Panthers driving off road probably did break down more often than Shermans, but that is because they were prone to break down in general, not because they were off-road.

... which is pretty much the exact opposite of what you just claimed I was arguing.

[Vanir Ausf B]

expected fatigue life of 150 km means it is a fragile piece of equipment which could break if too much strain is put on it, i.e. moving uphill, downhill, turning. Moving offroad on uneven, muddy, soft sand just increases the strain and chances of a breakdown.

To put the 150 km in perspective, the drivetrain of a new quality car is designed to last at least 100,000 km.

How do you know that 150 km doesn't assume off-road mileage? You don't.

The comparison to a new modern car is very apropos. I commend you on your depth of knowledge of the issue.

[c3k]

Flotation: the interleaved road wheels of the German "cats" were VERY good at distributing the weight across the entire track. Some tanks, despite having tracks, don't do that very well. The nearest Allied comparison would be the Churchill with its plethora of road wheels.

There was a great analysis posted, years ago, of something called "MMP" (?), mean maximum pressure (?), which demonstrated why that distribution is almost more important than just average pressure (determined by dividing the vehicle weight by the area of track in contact with the ground).

The suspension makes a HUGE difference in mobility. The Germans stumbled upon a very good solution.

[Baneman]

So if we can boil the thread down to one question it would be : Why is the Tiger rated better off-road than the Panther when the reverse was true in reality ?

Since all other tanks are given the 3-bar rating, their relative performance doesn't come into it ( although we'd love to know if there are degrees of difference within the 3-bar rating ).

[Sgt Joch]

This is just getting silly. Actually, it was silly before. Now its ridiculous.

I'm almost at a loss for words here.

I have detailed the Panther's various physical characteristics that gave it such excellent off-road performance. But when you get right down to it, the main factor was that it had very wide tracks relative to its weight.

When you say it was only more maneuverable than a Sherman under "ideal conditions" (whatever those are) you are essentially claiming that those wide tracks only functioned properly under ideal conditions.

Bizarre. :confused:

No they were not. You made up that claim out of thin air. I've already posted first person accounts of them operating in muddy conditions. If what you said was true they would have been essentially road-bound for half the year. Crazy talk.

The extremely muddy conditions relegated armour attacks to the few roads available. This forced any gains to be made to infantry attacks, which resulted in bloody battles and heavy casualties on both sides.

http://www.flamesofwar.com/Default.aspx?tabid=112&art_id=2211

_____

Congratulations. You have succeeded in proving the Panther had limits. But that has never been in question. The question is how it compared to other tanks.

Aaand here we go again with the predictable conflation of off-road ability and mechanical reliability. This is getting tedious so I'm just going to cut and paste what I previously wrote so you can not understand it all over again.

Right. That is what I want, to make German tanks perfect.

It is becoming more apparent with each post that you have no intention of debating this issue honestly and are just trying to derail the discussion under a torrent of idiocy.

If there are no major changes it will most likely be because Charles doesn't read this forum and Steve is probably oblivious to the issue. I can't imaging it being because they actually believe the crap you're peddling.

Still arguing? When did I say that? Oh, wait I didn't. What I actually said was:

... which is pretty much the exact opposite of what you just claimed I was arguing.

now you are just acting like a spoiled child.

[Vanir Ausf B]

So if we can boil the thread down to one question it would be : Why is the Tiger rated better off-road than the Panther when the reverse was true in reality ?

I've asked. The crickets are still chirping. Listen!

*chirp chirp chirp*

Since all other tanks are given the 3-bar rating, their relative performance doesn't come into it ( although we'd love to know if there are degrees of difference within the 3-bar rating ).

The big unsolved mystery is what are the ratings based on? I'm trying to think of something unique to the Tiger I that would explain it but all I can think of is that it's length to width ratio is close to the ideal. Somehow I don't think that's it.

In the CMx1 games it was a straight function of ground pressure. That is obviously not the case in CMx2.

[Vanir Ausf B]

Flotation: the interleaved road wheels of the German "cats" were VERY good at distributing the weight across the entire track. Some tanks, despite having tracks, don't do that very well. The nearest Allied comparison would be the Churchill with its plethora of road wheels.

There was a great analysis posted, years ago, of something called "MMP" (?), mean maximum pressure (?), which demonstrated why that distribution is almost more important than just average pressure (determined by dividing the vehicle weight by the area of track in contact with the ground).

The suspension makes a HUGE difference in mobility. The Germans stumbled upon a very good solution.

Yep. I mentioned MMP in the OP. Here's some links to technical pages.

http://ciar.org/ttk/mbt/soil-mechanics/

http://www.angelfire.com/trek/mytravels/militarygp.html

There was a discussion about it on the forum years ago (which you may be referring to)...

http://www.battlefront.com/community/showthread.php?t=38553

... in which someone familiar with the concept listed the MMP of various armored vehicles, which I will partially reproduce here:

Panther 150-155

M-24 Chaffee 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

JS-II 245

Sherman VVSS 282

Cromwell VII 300

Cromwell IV 352

M3 Halftrack 363

US 2 1/2 ton 367 (6X6)

Elephant 370

[Vanir Ausf B]

On the whole, nominal ground pressure has proven useful as a measure of the ability of tanks to move over soft soils and in particular for assessing their relative capabilities. Thus tanks with a low NGP have generally performed better over soft soils than similar tanks with a high NGP. However, NGP is no more than a gross approximation to the pressure exerted by tanks on the ground and fails to take into account the fact that pressure varies along the length of the track. In particular, it fails to take into account that peaks of the pressure, which occur under the road wheels, can be considerably higher than the average value...

Other experiments, carried out in Britain towards the end of the Second World War and afterwords, demonstrated further the shortcoming of NGP and the importance of peak pressure. One of the most telling of them involved a Churchill tank which had the number of its road wheels reduced from eleven to seven per side. This increased the average of the peak pressures under its tracks by 80 percent and more than doubled their sinkage, in spite of the fact that the NGP remained unchanged. In another experiment with a Cromwell tank the pitch of the track links was doubled and this reduced the average of the peak pressures by 29 percent and the sinkage by 33 percent although, once again, NGP remained unchanged.

...Physical reasoning leads to the conclusion that the maximum pressure under a track P(max) must be directly related to the weight acting on each of the road wheels and inversely rated to the width of the track, the pitch of its links and the diameter of the road wheels...

.....................

[Baneman]

... I'm trying to think of something unique to the Tiger I that would explain it but all I can think of is that it's length to width ratio is close to the ideal. Somehow I don't think that's it.

...

There's always the possibility that it's a simple typo - viz. BFC meant to give the 4 rating to the Panther, but a transposed digit somewhere gave it to the Tiger instead.

As a programmer myself, I know how easily that can happen.

[Thomm]

Physical reasoning leads to the conclusion that the maximum pressure under a track P(max) must be directly related to the weight acting on each of the road wheels and inversely rated to the width of the track, the pitch of its links and the diameter of the road wheels.

Should track tension not also be an important factor? As in: The higher the tension, the more even the pressure distribution?

Best regards,

Thomm

[Vanir Ausf B]

That sounds reasonable, but I don't see it in the papers. IIRC track tension is adjustable so may vary between individual vehicles.

[Dadekster]

Should track tension not also be an important factor? As in: The higher the tension, the more even the pressure distribution?

Best regards,

Thomm

It's a juggling act ime. Screwing around with the track tension to much could cause you to throw track easier depending on the kind of driving being done although the more common issue was breaking track teeth which just resulted in extra maintenance. That said I have zero experience driving any of the vehicles being discussed.

[Lethaface]

To put the 150 km in perspective, the drivetrain of a new quality car is designed to last at least 100,000 km.

Ahum, 'quality' cars drivetrain should generally last several 100.000 km's if properly maintained!