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Tank Off Road Performance Tests and Possible Wackiness


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But irregardless of the tank or the speed, it seems to be a constant 1%. That seems to be off. I would think that fast should be worse than slow.

Oh I see what you mean by 1% now. That's just because I tested 100 tanks. Total distance/100.

As far as Panthers and Shermans, I'd give Panthers the benefit of better flotation.

Flotation + interleaved road wheels + higher ground clearance (56 inches vs 43).

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He has a point, if the Panther was generally regarded as having the best off-road performance, then surely at the least it should be the one with the "4 bar" rating ( without going into what exactly the bars represent ) and not the Tiger.

Panther is only the best if you just look at one specific variable. The biggest problem with the Panther, Tiger and Tiger II were the weak transmission and drivetrain which had not been designed to handle such heavy vehicles. They were prone to breakdown just driving along a paved road. Crews were very reticent to take them offroad since that just increased the chances of a breakdown.

Sherman tanks were more reliable which in practice made more mobile.

Medium_tank_crosses_Suicide_Creek.jpg

I would like to see a Panther doing that...;)

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Panther is only the best if you just look at one specific variable. The biggest problem with the Panther, Tiger and Tiger II were the weak transmission and drivetrain which had not been designed to handle such heavy vehicles. They were prone to breakdown just driving along a paved road.

Apples to oranges. While what you say is true, mechanical reliability and soft ground performance are two very different things.

Crews were very reticent to take them offroad since that just increased the chances of a breakdown.

I have never read anything to support this.

I would like to see a Panther doing that...;)

Panther had better hill climbing and fording capability than the Sherman.

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I think what you might be obliquely referring to is the German preference for transporting their tanks via rail rather than road due to their tendency to break down on long road marches. But that was simply a factor of mileage rather than anything to do with on-road vs. off-road.

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actually would love to have those mechanical issues included too. About the only thing I worry about for vehicles is, am I driving through hedges/fences/vineyards?

I realize a lot of the mechanical reliability is primarily likely units that would fall out on road marches, but occasionally losing a drive train or something would be an interesting (and likely frustrating) variable.

Would be interesting if there could be mechanical issues in rubbled urban environments as well.

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Driving offroad will increase the stress on the vehicle's moving parts and cause more mechanical failures. This would especially be true during muddy or sandy conditions. So muddy conditions could cause mechanical failures regardless of theoretical performance for floatation purposes. This can be attributed to two different things of course, but the end result is the same. An immobilized tank.

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That is all very theoretical and not particularly relevant. CM does not model mechanical breakdown. Maybe it should, but it doesn't and it really is not the same thing as soft ground performance. 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. If you really want to model mechanical reliability then you need to assign a % chance that a tank you pick in your QB isn't there when the game starts.

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It is relevant because the current system is simplified and actually benefits the big German Cats which can basically go anywhere. You can't just argue that you should make them even more mobile...:)

IF we did go to a more realistic system, you would be worried about your Cats blowing a tranny as soon as you took them offroad...while the shermans would pretty much continue as is.

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It is relevant because the current system is simplified and actually benefits the big German Cats which can basically go anywhere. You can't just argue that you should make them even more mobile...:)

Of course I can. Because they were ;) The current system isn't simplified. It's just flat-out wrong. The only Big Cat that benefits from the present system is the Tiger I, oddly enough. Why BFC picked that one out of the bunch is anyone's guess.

IF we did go to a more realistic system, you would be worried about your Cats blowing a tranny as soon as you took them offroad...while the shermans would pretty much continue as is.

There is no evidence that "Big Cats" were any more likely to break down off-road vs. on-road than Shermans or any other tank. None. It is pure speculation. I have seen fuel consumption numbers broken down off-road vs on-road, speed broken down off-road vs. on road but I have only seen reliability numbers given in total km driven, which suggests it was not the huge factor people are imagining.

And frankly I would be fine with mechanical reliability being modeled in the game, but I would hope it would be given more thought than soft ground performance has been.

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There is no evidence that "Big Cats" were any more likely to break down off-road vs. on-road than Shermans or any other tank. None. It is pure speculation. I have seen fuel consumption numbers broken down off-road vs on-road, speed broken down off-road vs. on road but I have only seen reliability numbers given in total km driven, which suggests it was not the huge factor .

ok, this should be fun. :)

No matter which way you look at it, a tank that can last for over 40 years and still be in service all over the world has got to be counted as a success. Search now for the much vaunted Tigers and Panthers, and the only ones you will find are in museums, while the Sherman still soldiers on, getting the job done in an unspectacular yet businesslike way. As another of my correspondents, Les "Spud" Taylor, who served with the Northamptonshire Yeomanry, put it when I asked him what he liked best about the Sherman: First, its utter mechanical reliability. Our one same vehicle carried us from the bocage through the chase to the River Seine, the battle for Le Havre, then by tank transporter through northern France and Belgium to the south of Holland. Defending the corridor Nijmegen-Eindhoven during Operation MARKET GARDEN, clearing the Noord Brabant, then the long cold winter journey to the Ardennes and the Battle of the Bulge. It says much for the expertise of our American friends that during the many battles and actions, plus the wear and tear of that long journey, I can only recall one breakdown, when the rubber stripped off a couple of bogie wheels. It never let us down during the fighting and apart from the laborious task of replenishing with ammunition and fuel, the usual checks were all that it required. The turret power traverse often gave us the edge over the hand operated German types and, of course, being an American tank, it possessed an excellent toolkit". Twenty-five years on, if you had asked an Israeli tanker on the Golan Heights for his comments, I have no doubt they would have been very similar.

* The Tiger and Panther Tanks were notorious for either having just enough or simply not enough engine power. The transmission was a noted weak point by the drivers - and this was especially true in early Panthers. At Kursk, Panthers that tried to tow disabled Panthers would often end up with a blown transmission and disabled themselves. In Italy, there are several stories of Tigers being abandoned with burned out clutches. Disciplinary measures were adopted in order to halt tanks towing tanks unless there was absolutely no other choice. The interleaved road wheels contributed to mobility problems. I have noted many comments attesting to the Tiger's penchant to become immobilized in freezing conditions due to mud, rocks, or ice collecting between the road wheels. During normal conditions stones or mud could collect between the roadwheels and bind the tracks so tightly that the tank would become immobile. Under those conditions, loosening the idler would not even free the track. The German tanker was then advised to have his tank towed or, if in fear of having to abandon the tank, actually blow out a track link with an explosive charge. Crossing rivers and bridges was a real problem and hazardous. The sheer weight of these vehicles overcame bridge weight limits and ground normal road surfaces into rubble.

William Kirk

http://mailer.fsu.edu/~akirk/tanks/UnitedStates/mediumtanks/M4/Introduction.html

back to you.

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ok, this should be fun. :)

I see you passed on explaining away the Tiger performance. Hmm, I wonder why? ;)

back to you.

Your quotes are alternately beating a strawman or not relevant to the types of actions in CM. That the Big Cats were not mechanically reliable is not in question. It's simply not relevant no matter how hard you insist otherwise.

The issue with interleaved wheels is well known, but the circumstances in which these issues formed were usually fairly specific. If the wheels became caked with mud and the vehicle was let sit overnight in freezing temperatures the mud would freeze and the vehicle wouldn't move in the morning.

I'm pressed for time ATM, but in short you are making a lot of mistakes. You are conflating operational and tactical mobility, pretending the game models something it actually does not, claiming that mechanical reliably and soft ground performance are the same thing, ect. But I agree this will be fun.... for me ;)

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There are more examples than I can count of Tigers being forced to remain on a road to avoid risking immobilization. Proving that is as easy as shooting fish in a barrel - which I believe the mythbusters actually proved is pretty easy to do. :)

All tanks did. You'd have to do some serious cherrypicking to claim otherwise.

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All tanks did. You'd have to do some serious cherrypicking to claim otherwise.

Wow. It is seriously easy to find instances where the Tiger tanks inability to go offroad has a direct impact on that tank's performance in a specific battle. Instances in which the same offroad environmental conditions did not have a similar impact on other vehicles. To claim otherwise is .... well I'll leave it at that.

Edited to modify my initial remarks and to add the following:

Terrain in this area was extremely sandy, forcing the King Tigers to stay primarily on the existing roads.

(snip)

Soviet forces in this area primarily used defensive tactics, positioning tanks and assault guns in hidden ambush positions focused on the known German avenues of approach, the roads.

(snip)

Soviet sources credit the maneuverability of their tanks as a primary attribute to their success, allowing them to move to key defensible terrain instead of staying tied to the roads like the King Tigers.

(snip)

The results of Soviet testing indicated a low mechanical reliability in terms of the King Tiger’s chassis, engine, and transmission. Additionally, the performance specifications for the King Tiger by the Germans was found to be extremely inflated or optimistic.

That's just one I happened to find in about five minutes. The Soviets were using IS2, SU122, and T34 tanks in that particular battle. I can give you several more examples too, although I'm not sure it's worth my time doing so. However, there are plenty of examples from Anzio with Tigers and Elefants where they were stuck to the road. You can also find numerous examples from German operations around Budapest as well with Tigers stuck to the roads. Like I said, examples are easy to find. Of course you have to want to see the examples and admit to their relevance otherwise it makes no difference how many examples are quoted.

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I'm going to guess that those instances are primarily in Italy and/or involve steep hills, or perhaps bridges, rather than soft ground -- you know, the actual subject of this thread. If that is not the case, then I'm sure you will have no trouble citing them, being that they are so easy to find.

Interesting that you keep bringing up the Tiger tank. I'm still waiting for an explanation for it's excellent off-road performance in-game. By your own logic the game has it wrong. I think it is you who has argued yourself into a corner.

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Just saw your edit. Why am I not surprised that it turns out to be another straw man. Here we are discussing off-road performance of Big Cats and Shermans and you come back with a comparison to Soviet tanks, which have not even been mentioned :rolleyes:

First of all those are KTs not Tigers. Secondly, although I don't have the specs for IS-2 at hand, the T-34 has excellent flotation. Better than KT or Tiger. MUCH better than the Sherman. So you are once again arguing against a claim I never made.

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Ah, back home. Now to begin the pulling of teeth :P

This shouldn't be particularly controversial. I was under the impression that these things were common knowledge among WW2 aficionados. Guess not.

First off, since some people are throwing everything including the kitchen sink into the discussion under the misguided notion that it all amounts to the same thing, it may be time to define a few things. For one, this thread deals with off-road mobility in general and soft soil performance in particular. It is tangentially related to fording, hill climbing and other cross-country performance factors. It has virtually nothing to do with mechanical reliability, fuel consumption or whatever other operational factor you keep tossing into the ring in an attempt to obfuscate the issue. CM does not model those factors and no amount of wishful thinking is going to change that.

Next, in case it wasn't obvious enough, this primarily concerns the Panther, Tiger, KT and Sherman series of vehicles and now they perform relative to each other. Other vehicles may be referenced at times but are not the subject of my testing.

As for tactical and operational mobility factors, here's a primer on what they are and why some of them are more relevant to CM than others (hint: CM is a fairly low-level tactical wargame).

Tactical mobility generally describes a tank's ability to operate on the battlefield in a variety of terrain and weather conditions. The things that come into play with tactical mobility are the speed, maneuverability and cross-country performance of a tank. Within the parameter of speed are things like engine power, acceleration, average speed, and creep speed. Maneuverability includes a tank's braking capability, pivot turns, and steering gear ratios, while a tank's cross-country performance includes fording depth, vertical obstacles, ground pressure and grade climbing ability. In the case of the Panther tank, its tactical mobility surpassed the Sherman tank and that of the T-34 tank series.

Operational mobility is concerned with how an army masses its tanks in the rear areas and how it moves them toward a combat area (by sea, rail, or on their own power) in sufficient numbers within a certain time frame to influence the course of events in their favor.

The things that come into play with tanks in regard to operational mobility include their weight and dimensions, cruising speed, radius of action, and rail and road transport issues. It is here that the Panther tank, with its gasoline-powered engine, pales in comparison to the T-34 tank series with its diesel engine, which increased the radius of action compared to the Panther tank. Add to that the T-34 tank series general mechanical reliability versus the mechanical unreliability of the Panther tank and one can see how that Russian tank allowed the Red Army to prevail in World War II...

...While the gasoline-powered versions of the Sherman tank lacked the wide radius of action of the T-34 tank series, it shared the important factor of reliability, and that, in conjunction with the combined arms approach to combat practiced by the Western Allies during World War II, allowed them to generally prevail on the battlefields of Western Europe over the much smaller number of Panther tanks encountered.

-- excerpt from Panther: Germany's Quest For Combat Dominance by Michael and Gladys Green

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Now, as for why the Panther had such excellent cross-country mobility, I've already quoted the ground pressure, ground clearance and MMP numbers in the OP, which should speak for themselves. But there were a few other factors as well.

First, the interleaved road wheels, which were indeed a maintenance nightmare but had some advantages.

One lesson learned by the Germans early in World War II was that the highest loaded road wheel on a track determined how deep that track would sink in soft soil. This lesson was applied to the Panther tank suspension design with its interleaved or overlapping road wheels, which provided more road wheels to support the load hence lower unit ground pressure with less sinkage. This benefit can become an important factor with a column of tanks crossing a soft soil field that might have planted land mines. In this case tanks would often stay in a column playing "follow the leader" for the sake of safety. Ruts would be formed by the tracks and excessive sinkage into the soil was very undesirable because at some point hull bottom contact occurs and the mired down vehicle(s) may have to be towed free.

Also, the twin torsion bar suspension on the Panther provided an unusually smooth cross-country ride.

The two torsion bars springing each road wheel were connected in series, i.e., the first bar was connected to the road arm and spanned the width of the hull, where it was linked to a second identical bar running parallel to the first. The second bar was then anchored to the hull adjacent to the first bar's road arm bearing. The net effect was to greatly soften the spring rate and permit increased road wheel vertical travel, reducing the incidents of "suspension bottoming", significantly improving cross-country performance.

As the Panther tank went over uneven ground, the mass of the vehicle acting against the motion of the road arms caused the twin torsion bars to rotate. The twisting action of the twin torsion bars pushed the road wheels down to keep them on the ground. Because the pure springing action of the twin torsion bars alone would cause the Panther tank to pitch uncontrollably, even on relatively smooth ground, the tank had shock absorbers fitted to its suspension system road arms to prevent the vehicle from oscillating. The reduction of oscillation is known as damping, which is important to reduce crew fatigue and motion sickness when traveling rough terrain at high speeds.

The torsion bar arrangement on the Panther tank provided it with a suspension travel of 20 inches (51 cm). By way of comparison, the German Tiger Ausf. E and B heavy tanks had a bit less than 9 inches (23 cm) of suspension travel, while the T-34 tank series had roughly 9.5 inches (23 cm) of suspension travel. The first-generation Sherman tank had only about 4 inches (10.2 cm) of suspension travel.

-- excerpts from Panther: Germany's Quest For Combat Dominance

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And what about that Sherman tank? I mentioned earlier that the US Army went to considerable effort to shore up the Sherman's off-road performance in the fall of '44. They weren't doing that for ****s and giggles. They were learning the same hard lessons the Germans had learned in Russia several years earlier.

The sodden soil along the Siegfried Line restricted tank mobility for much of the autumn of 1944. Sherman tanks quickly became bogged down in the mud, and tank crews learned to stay on the roads. Sherman crews became infuriated as they watched heavier German tanks such as the Panther and King Tiger traverse fields that only moments before had frustrated American tanks. Indeed, the Panther, nearly twice the weight of the Sherman, had a significant advantage in soft terrain because of its wider tracks. It had a ground pressure of 12.3 psi while the much smaller and lighter Sherman had a higher 15.1 psi ground pressure. The Panther's wide tracks were a legacy of the Russian front and patterned after the wide tracks of the Soviet T-34. The Sherman's narrow tracks had proven perfectly adequate in Tunisia, Sicily, Italy, and France. But the Sherman was no match for the German mud.

The solution was duck bills, or to use their official name, "extended end connectors". Ordinance was well aware of the Sherman's flotation problem in soft soil and had already developed a solution in the form of a new suspension system. The Sherman had been using a vertical-volute-spring (VVS) suspension system, which restricted the width of tracks since it could accommodate only a single road wheel. The new horizontal-volute-spring system (HVSS) could accommodate two road wheels per station, and so mounted a wider twenty-three inch track that offered a ground pressure of 10.7 psi, better than the Panther's. Production of tanks with the new suspension was authorized in March 1944 and began in August 1944, but the first tanks with this feature would not appear on the front lines until Christmas 1944 -- a reminder of the problems faced by the US Army when operating so far from home. Germany could get new tanks from the factory to front line units in about three weeks, for the US Army it took three months longer.

In the interim, something had to be done quickly. Ordinance had already come up with a simple solution in the form of a modified end connector that extended the existing track by about four inches, reducing the Sherman's ground pressure to 12.4 psi, only a little higher than the Panther's. The problem was that these extended end connectors were in short supply, and it would take months to ship enough to Europe. The solution was to make do with the resources at hand, particularly underutilized factories in Belgium and northern France. The extended end connectors were a relatively simple casting that could be managed by many European foundries which were idle because of the chaos of war. Bradley's 12th Army Group simply began having the local firms cast hundreds of thousands of these "duck bills", which were then issued to American and British Sherman units. A shortage of foundries led to local improvisations, such as creating the duck bills by welding an extension to existing end connectors. By November, most Shermans were sporting the duck bills and having an easier time traversing terrain.

-- excerpt from Armored Thunderbolt: The U.S. Army Sherman in World War II by Steven Zaloga

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It was earlier claimed or implied that the Sherman had superior fording and climbing ability to the Panther. It so happens the US Army put that question to the test.

The Mark V tank forded water to a depth of 59 inches. Although it would take greater depth for a short period of time (up to 70 inches), there was a tendency for water to splash through the fan openings in the top deck. The M4A3E8 forded water safely up to 30 inches. It could ford up to 36 inches, but water tended to splash into the exhaust.

-- U.S. Army Report on United States vs German Armor, March 27, 1945

The first operation was on a 28% dirt slope that was frozen solid and partially covered with ice. The Panther tank negotiated this slope in both directions with ease and there was virtually no track slippage, even during steering. Medium tank M4 equipped with the chevron steel grouser tracks T54E1, and with the rubber block track T51 equipped with a standard grouser on every block were unable to climb the slope. A heavy tank T26E3 equipped with a modified T81 track was also unable to climb the slope. This modified T81 track varies from the standard track in that it has high grousers for additional traction.

-- U.S. Army report, January 4, 1945

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Its very easy to cherry pick quotes from secondary sources, but let's see what the people who actually operated Panthers thought. The French operated Panthers postwar and prepared a report in 1947:

"The truly weak spot of the Panther is its final drive, which is of too weak a design and has an average fatigue life of only 150 km."

[Chieftain's note. This is and the engine comment is notwithstanding the above statement by Mr Jentz. Does 'reliable' mean 'will always work', or 'will always work when you expect it to?' And were these shortcomings countered by comparative reliability advantages elsewhere? It is worth noting that in the opinion of Hilary Doyle, there was little unacceptable about the quality of the late-war Panther: See Operation Think Tank discussion]

­Half of the abandoned Panthers found in Normandy in 1944 showed evidence of breaks in the final drive.

It takes only one weak link to break a chain. The Panther had many fine qualities. But here we find a severe weakness.

­ "In order to prevent these breaks it is recommended that the following points be closely observed: when driving downhill and in reverse as well as on uneven terrain to be particularly careful when shifting to a lower gear. In addition, a Panther should never be towed without uncoupling the final drive previously. Finally, under no circumstances should both steering levers be operated simultaneously ­ regardless of the situation."

American tankers often observed that the Panther could “neutral steer” – it could pivot in place by moving one track forward, and the other backwards. The Sherman did not have this capability.

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.

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

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. Weak side armor; tank top vulnerable to fighter-bombers. Fuel lines of porous material that allow gasoline fumes to escape into the tank interior causing a grave fire hazard. Absence of vision slits makes defense against close attack impossible.

http://worldoftanks.com/en/news/21/chieftains-hatch-french-panthers/

You also have this which is apparently from contemporary German reports (ref: Spielberger. Panther & Its Variants page 160), but I have seen it:

Yet even German documents showed that it had considerable weak-

nesses:

- Inadequate for strategic mobility due to the short fatigue life of its

engine, which lay between six and seven times the vehicle's range. The

Panther cannot cover large distances and must restrict itself to short

distances.

- Deficiency in mobility due to an inadequate steering mechanism,

which had a very high breakdown rate.

- Operations required generally specialized personnel: in the Wehr-

macht an officeror Oberfeldwebel as tank commander, Unteroffiziers as

gunner and driver.

Once the Germans no longer had any experienced tank crews, it was

apparent that the Panthers were no longer employed operationally or

were abandoned because of mechanical breakdowns.

http://www.armchairgeneral.com/forums/showthread.php?t=110002

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