Torsion Bar Suspension Analysis: A Panther Primer

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Kawinksy
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Re: Torsion Bar Suspension Analysis: A Panther Primer

#46

Post by Kawinksy » 03 Mar 2019, 08:43

Michael Kenny wrote:
02 Mar 2019, 21:26
The pic posted in the previous post is said to be a LAC photo in the linked site but I know it is from the IWM 'CL' Series of photos (CL398)and that means taken by an RAF cameraman. Clearly the RAF had it marked down as a 'air-kill'!
When was this air photo taken? I only see a tank on the right side of the road...
Could you provide a better image quality?

Image

Composite air photo:
https://scholars.wlu.ca/cgi/viewcontent ... mh#page=17

Michael Kenny
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Re: Torsion Bar Suspension Analysis: A Panther Primer

#47

Post by Michael Kenny » 03 Mar 2019, 15:30

Kawinksy wrote:
03 Mar 2019, 08:43


When was this air photo taken?
June 24th 1944, 400-0283 (3005)

https://ncap.org.uk/search?keywords=400-0283

Kawinksy wrote:
03 Mar 2019, 08:43
I only see a tank on the right side of the road...
The object in your yellow square is not a tank. It is far too big. Compare it to the Panthers at the bottom RH corner.
Screenshot_2.vbhgfgpnng.jpg
The hull was still there in October 1945

IGNF_PVA_1-0__1945-10-12__C1512-0101_1945_CDP14_0652 b,.jpg
IGNF_PVA_1-0__1945-10-12__C1512-0101_1945_CDP14_0652 bb.jpg
click on the yellow dot 3rd from right on the bottom row here:

https://remonterletemps.ign.fr/telechar ... ns.4980370


Kawinksy
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Re: Torsion Bar Suspension Analysis: A Panther Primer

#48

Post by Kawinksy » 03 Mar 2019, 16:37

Michael Kenny wrote:
03 Mar 2019, 15:30
The object in your yellow square is not a tank. It is far too big. Compare it to the Panthers at the bottom RH corner.

click on the yellow dot 3rd from right on the bottom row here:

https://remonterletemps.ign.fr/telechar ... ns.4980370
Great pictures and research, thank you Michael!
What do you think it might be?

Andrei

Yoozername
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Re: Torsion Bar Suspension Analysis: A Panther Primer

#49

Post by Yoozername » 03 Mar 2019, 19:33

Kawinksy wrote:
03 Mar 2019, 16:37
Michael Kenny wrote:
03 Mar 2019, 15:30
The object in your yellow square is not a tank. It is far too big. Compare it to the Panthers at the bottom RH corner.

click on the yellow dot 3rd from right on the bottom row here:

https://remonterletemps.ign.fr/telechar ... ns.4980370
Great pictures and research, thank you Michael!
What do you think it might be?

Andrei
Maybe if the aerial photos were overlapping, we could use one of these? (81C20)

Image

Yoozername
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Re: Torsion Bar Suspension Analysis: A Panther Primer

#50

Post by Yoozername » 04 Mar 2019, 23:35


critical mass
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Re: Torsion Bar Suspension Analysis: A Panther Primer

#51

Post by critical mass » 08 Mar 2019, 20:19

This is a good video showing the fucntion of the rather unique dual torsion bar suspension of the PANTHER, Yoozername.

The ability of the torsion bar to twist is constrained by two factors: it´s length, which by virtue of the transverse installation is equal to the witdh of the hull and the shear stress limit of the torsion bar. Because the shear strength is relatively fixed due to the availability of steel alloy, the PANTHER eventually adopted an doubling of effective length by connecting two parallel torsion bars.
Dual torsion bar gives high storage energy and very high deflection (340mm bump travel and 510mm total deflection for the roadwheels of the PANTHER, with a ground clearance of 560mm). However, they do require more internal space than single torsion bars and consequently, a higher floorplate, resulting in lower internal volume.
It´s often used to show that the PANTHER had excellent supension. This indeed was the case even compared to 1st generation of post war tanks but I ask myselfe what for? This tank wasn´t powered high enough to make good use of such excess suspensions capabilities, except in rather remote chances. The motorization is too low. The undulating track tests showed that the limit of the suspension over undulating, concrete test track was not reached at top speed. In other words, the engine power would be exceeded much before the suspension limit was encountered even in perfectly hard surface conditions. Under normal, soft soil conditions, the suspension is somewhat excessive. It looks like the PANTHER is buildt with suspension specifications for cross country, high speed requirements of a light tank in mind, despite weighting a whopping 45t.
If this is found to be correct it follows that there is some indication that single torsion bars instead, such as envisioned for the PANTHER II would have likely materially improved the design: 1st) by reducing the total travel, the ground clearence could be reduced without undue loss of cross country mobility as long as the AFV is powered by 600-800hp class engines. This would have resulted in a desirable lowering of the total height of the tank.
2nd) by reducing the internal space required under the floor for the deflection of dual torsion bars to the considerably lower needs of single torsion bars, either an increased internal volume, or, alternatively, a further reduction of height of the AFV could have been obtained. 3rd) a reduction of weight would have resulted.

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Re: Torsion Bar Suspension Analysis: A Panther Primer

#52

Post by Yoozername » 08 Mar 2019, 20:57

I think it is, much like the Tiger I early suspension, "High Church", and not really a very good design choice for a new AFV in mid-war. The number of actual wheels, and the amount of torsion bars, all slows down production on a AFV meant for large production. The JS-2 had torsion bar suspension but I believe it was actually not as wide as the vehicle itself.

The interleaved suspension was a WWII development that ended with WWII. Most modern suspensions have evolved to pretty much the same design. Torsion bars are still viable in some modern AFV. The Panther actually could climb over obstacles very well, even hedgerows, but it was a design that ignored many realities, not the least was the number of AFV Germany's enemies were making. Also, its design was hampered by imagined super-tanks that did not show up. It would have been fine with a 60mm glacis armor, and a diesel motor and simpler transmission.

critical mass
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Re: Torsion Bar Suspension Analysis: A Panther Primer

#53

Post by critical mass » 10 Mar 2019, 12:15

The IS´s suspension system was adaequate for the task in question, that is to propel a heavy tank through dirt roads at a relatively low but consistent speed of advance (with temporary periods of high speed) and off roads at low speed. It does, however, not have as high ground clearance or as low an MMP as the cats. That this deficit did not materialize in practice does lend some support to the idea that the PANTHER/TIGER suspension systems were kind of over-engeneered. In my subjective opinion, it would be interesting whether or not the sources support a hypothetical construction of a connection between the german experience in the first soviet Rasputza in autumn 1941 and the requirement of "excess" soft terrain passability in response.

In defense of their practice, they attempted an unprecedented jump in the scale of weight: from the 24t PzIVE/F1 to the 56t TIGERI and the 44t PANTHER D. Excess suspension capacity may function in this context as a guard against the unknown. The PANTHER came close to be cancelled, additional suspension trouble might be just enough to actually reject the AFV.

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hesh1380
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Re: Torsion Bar Suspension Analysis: A Panther Primer

#54

Post by hesh1380 » 12 Mar 2019, 08:07

Well, the panther's suspension WAS good, but the tank weighed 45 tons, so it was overweight and thats why it didn't do very well mobility wise
the complete idiot who likes russian bias...

In other news, I'm open to ideas for almost anything. Mostly fake projects for WW2.

Yoozername
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Re: Torsion Bar Suspension Analysis: A Panther Primer

#55

Post by Yoozername » 12 Mar 2019, 18:43

Some good points here. My thought about mentioning the JS-II is the weight class is about the same as the Panther, but I would agree the suspension is basically handling a top speed of around 24 MPH. Could the Panther, if it had no motor or drivetrain issues, really drive at 30+ MPH for extended periods? Would something else fail? Sprocket? Tracks? Hard to tell with WWII technology.

The JS-II was known to have a reserve of power, and it is even mentioned as being a good capture to use for towing heavy tanks, etc. Diesel engines do have superior torque, as well as range. Turretless T-34s were also used by units as tugs.

The Panther did have good cross-country and obstacle climbing characteristics. It was certainly addressing 'East-Front' terrain and weather. But given the distances on the east front, and the actual technical limitations of the Panther, it was limited to long hauls on rail roads and given the nature of the battlefields in the west, this would not work as well as in the east.

The Germans didn't learn the lesson of using diesel fuel. They really went into unknown territory with the Tiger I and Panther programs, and they did not choose wisely. Funny that as late as 1945 Hitler was asking about diesel tanks.

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Mobius
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Re: Torsion Bar Suspension Analysis: A Panther Primer

#56

Post by Mobius » 13 Mar 2019, 06:26

Yoozername wrote:
12 Mar 2019, 18:43
The Germans didn't learn the lesson of using diesel fuel. They really went into unknown territory with the Tiger I and Panther programs, and they did not choose wisely. Funny that as late as 1945 Hitler was asking about diesel tanks.
I recall reading that there were some issues producing synthetic diesel fuel opposed to gasoline like fuel. Also a barrel of oil produces more gasoline than diesel.

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hesh1380
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Re: Torsion Bar Suspension Analysis: A Panther Primer

#57

Post by hesh1380 » 13 Mar 2019, 07:48

also the VK 30.01/02 DB had a diesel engine, (panther competitor) and looked like the t-34 had the same gun 7.5cm L/70, but a smaller turret and less effective armor
the complete idiot who likes russian bias...

In other news, I'm open to ideas for almost anything. Mostly fake projects for WW2.

critical mass
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Re: Torsion Bar Suspension Analysis: A Panther Primer

#58

Post by critical mass » 14 Mar 2019, 17:47

Yoozername wrote:
12 Mar 2019, 18:43
Some good points here. My thought about mentioning the JS-II is the weight class is about the same as the Panther, but I would agree the suspension is basically handling a top speed of around 24 MPH. Could the Panther, if it had no motor or drivetrain issues, really drive at 30+ MPH for extended periods? Would something else fail? Sprocket? Tracks? Hard to tell with WWII technology.

The Panther did have good cross-country and obstacle climbing characteristics. It was certainly addressing 'East-Front' terrain and weather. But given the distances on the east front, and the actual technical limitations of the Panther, it was limited to long hauls on rail roads and given the nature of the battlefields in the west, this would not work as well as in the east.

Its notweorthy to point out that the documents Art retrieved point out that in summer / autumn 1944, the IS-2 service life was still fairly short, with significant damage to running gear occurring after 700-800km (bend torsions, damaged road wheels, track link damage, engine damage) after road marches with avg. 5-6km/h (time to pause are accounted for).

As You mention, it´s cross country mobility was advanced, giving excellent tactical mobility and speed. The PANTHER had excess running gear capacity for the task at hand. However, the problem with the PANTHER was not in battlefield mobility but in strategic mobility. While it could negotiate deep snow and marshy or soft soil like no other medium AFV in ww2, it also was large and heavy, required an enormous amount of logistic capacity, train operation, a lot of fuel, excess demands in stockpiling of spare parts and maintenance due to many elements failing untimely. This meant less of these resources were avialable for other units and ultimately, it let to a higher ratio of AFV been abandoned whenever fluid maneuvre warfare demanded a great frequency of rapid changes of location.

And this is exactly where the M4 and T34 excelled (not so much the IS-2, though). You could rely on them to execute a deep penetration or a rapid retreat without an undue number of tanks beeing knocked out mechanically, and this helps a lot, preserving the fighting strength of a combat unit.

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Re: Torsion Bar Suspension Analysis: A Panther Primer

#59

Post by Yoozername » 14 Mar 2019, 18:12

True on many points, but the Soviets would probably point out that the JS-2 was really meant as a heavy tank for breakthrough operations. The Soviets did value the Shermans for their operational warfare where they have broken through and can exploit many kilometers deep into enemy territory. The T34/85 was a natural evolution of a mass produced vehicle. The Soviets, in retrospect, chose wisely.

As far as diesel, the Germans were capable of refining it from crude or synthetic oil. My understanding is that aviation fuel ('high test' gasoline) had priority on the synthetic oil production, and regular gasoline and diesel was made with whatever they could make it from. The Germans were using 'gasohol' for their vehicles also, basically cutting alcohol (ethanol) into the gasoline as an extender. Most tank engines of WWII were really low compression compared to modern gas engines in cars. The Panther was like 6.8:1. Since I like to experiment with ethanol blends in my own vehicles, I really wonder about how well gas/alk mix would work at that low a compression. On a cold morning, it would be another issue just starting it.

But I don't think the Germans had a diesel engine for the power requirements of a Tiger I or a Panther. Diesels do give better mileage (and range), and more importantly in heavy vehicles, more lower end torque to get the thing moving. It is also easier to refine diesel than gasoline. Hitler early in the war did ask about it but evidently was swayed away from using it in AFV.

critical mass
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Re: Torsion Bar Suspension Analysis: A Panther Primer

#60

Post by critical mass » 14 Mar 2019, 21:46

They had the opposed piston Diesel of the Jumo 204 and 205 series in production since the early 1930s. It’s the engine which inspired development of the 5TD series soviet tank diesels of the 1960s.
750 and 880hp, respectively should be enough for a Tiger, even if derated. Although it was an aerial engine, it was also successfully adapted for use in confined engine spaces of small navy vessels (LS, light attack craft).
These engines had nearly constant torque and very low specific fuel consumption. It was very light without supercharger and reliable and long lasting in service. It was, however, very high, though. Geometrically, one could turn the engine flat, like the Junkers Fo2 predecessor from 1918. The soviets later turned their engine flat, too, in order to provide a very low engine deck for their T64, but this came with a lot of cooling issues.

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