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StuG III Thread (and also other German vehicles I guess)


EnsignExpendable

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Alright, here is the story of 8.8cm KwK 43 L71 on heavy tanks, per Doyle and Jentz:

 

-The first attempt to put a KwK 43 on a tank was actually a proposal from Porsche from early 1942.  They would use a modified VK 45.01(p) (Porsche tiger).  Initially this was supposed to be a very straightforward modification of the Porsche tiger, simply with a new turret from Krupp to accommodate the larger armament.  However, the concept evolved, and at some point someone decided the thing ought to have sloped armor.

 

-The modified turret design somehow evolved from the familiar tiger I turret into an early iteration of the rounded-front tiger II turret (the one we erroneously call the "porsche turret" even though it's a Krupp design).  No trace of the intermediate stages has been discovered.  The final design that would be used on some early tiger IIs shared no components with previously designed turrets, and was one of Krupp's earlier attempts to design a turret with low frontal area.

 

-As usual, Dr. Porsche couldn't help himself and kept adding more modifications to the design.  He particularly seems to have relished designing alternative power trains.  Here is one iteration, the Porsche Type 180, recognizable to players of World of Tanks under the somewhat fictionalized designation VK 45.02A:

 

VNkcM3H.png?1

 

Note the insane suspension design.  The road wheels are sprung with torsion bars, but not normal, sane torsion bars that live in the hull.  Each pair of road wheels shares a torsion bar, slung in those pods underneath the road wheels.  They are sprung against the wheels by a mind-bendingly complicated system of cams and levers.  A small number of jagdtigers were made with this suspension system, as it reduced the man-hours from boring holes in the hull side plates for internal torsion bars; an operation that only the Germans have ever had problems with.

 

Note also that, despite having the transmission, drive sprocket and engine all in the rear hull and having external suspension, the good people at Krupp have not seen fit to extend the turret basket to the floor of the hull.  There's at least a foot of additional space they're not using FOR NO REASON AT ALL.

 

-Henschel started design of an improved Tiger that was called VK 45.02 in late 1942.  This evolved into the production tiger II via a long and convoluted route.  Per Doyle and Jentz, even from an early stage the turret design of this tank was essentially the same as for the Porsche designs, with the sole difference being that the turret traverse gear was designed to work with the Henschel drivetrain rather than the Porsche one.

 

 

Tiger I turret with KwK 43 is not mentioned at all in my sources, but I have been unable to obtain the ones where it is.  Perhaps it was a proposal for an in-line change or retrofit, unrelated to the main thrust of tiger II development.

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The Swedish army was fooled by the rumours of GERMAN ENGINEERING QUALITY too and bought a ZF electromechanical gearbox for the strv m/42, primarily because it was light and the army was desperately trying to save a few kilograms, and because there were no Swedish tanks heavier than 10 tons at the time and there was no time to develop a new gearbox domestically.

 

The thing turned out to be so fucking unreliable that the army suspected sabotage and started an investigative commission which asked some very pointed questions to the ordnance department (who had ordered it) and Landsverk (who built the tank) and sent an investigator to Germany to see if prisoners of war were fucking shit up. It took years and three or four iterations to sort the problems out and bringing the gearbox up to an acceptable level of reliability. In October 1944 the 3rd Armored Regiment at Strängnäs reported that 51 out of 89 strv m/42's with the ZF gearbox were unserviceable. Many of the moving parts in the gearbox were found to be made of materials completely inappropriate to the conditions they were supposed to work in, and tended to break or overheat after tens of kilometers on the road. Eventually the problem was mostly solved by replacing parts with Swedish-manufactured ones of higher quality and adjusting the lubrication several times, but the problem wasn't really solved until late 1944/early 1945.

 

(mostly) Actual quotes from the sales engineers:

- "oh we're using it in our SIXTY TON TIGER"

- "the magnetic plates are basically eternal, they'll last forever" (actually made of garbage quality steel full of dross, broke early and often)

- "electromagnetic gearboxes are the future, within three or four years they'll be the only gearbox used on new tanks" (said in 1942)

- "Sweden is the only country we're exporting these to, the design is actually classified you know"

- "well, we can't leave any guarantees that our gearboxes will work a fixed number of kilometers or anything, but we're convinced you'll be satisified with them"

- "we promise on our good reputation as a high quality engineering firm that these gearboxes will be good"

 

Fucking scammers.

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Very interesting information, rehanxue.

 

Just so everyone is clear, the picture I posted above was not the series production panther transmission.  That is a proposed upgrade that was, at most, experimentally trialed.

 

Which is a pity; from what renhanxue is saying, it sounds like the war could have been over faster if they had.

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Right. The designation for the ZF gearbox for the m/42 was 6 EV 75, IIRC. Meanwhile the army studied captured T-34's in Finland and was like "well, clearly a purely mechanical gearbox is possible, can we please get one like on the T-34 instead of these hydraulic and electromagnetic things?". Then Volvo eventually designed such a gearbox (which I suspect was inspired by the one on the T-34) called VL 420 which was used on the pvkv m/43 TD (same chassis), and a few years after the war all the remaining m/42's with ZF's electromagnetic shit were also refitted with the VL 420, ending the ZF design's miserable existence for good.

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